[PATCH v6 00/11] MediaTek DisplayPort: support eDP and aux-bus

[PATCH v6 00/11] MediaTek DisplayPort: support eDP and aux-bus

[AngeloGioacchino Del Regno]

Changes in v6:
 - Added some previously missing error checking (patch [01/11])
 - Added error checks for devm_drm_bridge_add()
 - Made sure that cable_plugged_in is set to false if HPD assertion
   polling fails (timeout)
 - Support panel as module (tested with panel-edp on MT8195 Tomato)
 - Rebased over next-20230717

Changes in v5:
 - Added .wait_hpd_asserted() callback for aux-bus
 - Avoid enabling and registering HPD interrupt + handlers for
   eDP case only (keeps HPD interrupts enabled for full DP case)
 - Support not always-on eDP panels (boot with regulator off,
   suspend with regulator off) for power saving in PM suspend.

Changes in v4:
 - Set data lanes to idle to prevent stalls if bootloader didn't
   properly close the eDP port
 - Now using the .done_probing() callback for AUX bus to prevent
   probe deferral loops in case the panel-edp driver is a module
   as previously seen with another bridge driver (ANX7625) on
   some other SoCs (MT8192 and others)
 - Rebased over next-20230706
 - Dropped Chen-Yu's T-b tag on last patch as some logic changed
   (before, I wasn't using the .done_probing() callback).

Changes in v3:
 - Added DPTX AUX block initialization before trying to communicate
   to stop relying on the bootloader keeping it initialized before
   booting Linux.
 - Fixed commit description for patch [09/09] and removed commented
   out code (that slipped from dev phase.. sorry!).

This series adds "real" support for eDP in the mtk-dp DisplayPort driver.

Explaining the "real":
Before this change, the DisplayPort driver did support eDP to some
extent, but it was treating it entirely like a regular DP interface
which is partially fine, after all, embedded DisplayPort *is* actually
DisplayPort, but there might be some differences to account for... and
this is for both small performance improvements and, more importantly,
for correct functionality in some systems.

Functionality first:

One of the common differences found in various boards implementing eDP
and machines using an eDP panel is that many times the HPD line is not
connected. This *must* be accounted for: at startup, this specific IP
will raise a HPD interrupt (which should maybe be ignored... as it does
not appear to be a "real" event...) that will make the eDP panel to be
detected and to actually work but, after a suspend-resume cycle, there
will be no HPD interrupt (as there's no HPD line in my case!) producing
a functionality issue - specifically, the DP Link Training fails because
the panel doesn't get powered up, then it stays black and won't work
until rebooting the machine (or removing and reinserting the module I
think, but I haven't tried that).

Now for.. both:
eDP panels are *e*DP because they are *not* removable (in the sense that
you can't unplug the cable without disassembling the machine, in which
case, the machine shall be powered down..!): this (correct) assumption
makes us able to solve some issues and to also gain a little performance
during PM operations.

What was done here is:
 - Caching the EDID if the panel is eDP: we're always going to read the
   same data everytime, so we can just cache that (as it's small enough)
   shortening PM resume times for the eDP driver instance;
 - Always return connector_status_connected if it's eDP: non-removable
   means connector_status_disconnected can't happen during runtime...
   this also saves us some time and even power, as we won't have to
   perform yet another power cycle of the HW;
 - Added aux-bus support!
   This makes us able to rely on panel autodetection from the EDID,
   avoiding to add more and more panel timings to panel-edp and, even
   better, allowing to use one panel node in devicetrees for multiple
   variants of the same machine since, at that point, it's not important
   to "preventively know" what panel we have (eh, it's autodetected...!).

This was tested on a MT8195 Cherry Tomato Chromebook (panel-edp on aux-bus)


P.S.: For your own testing commodity, here's a reference devicetree:

pp3300_disp_x: regulator-pp3300-disp-x {
	compatible = "regulator-fixed";
	regulator-name = "pp3300_disp_x";
	regulator-min-microvolt = <3300000>;
	regulator-max-microvolt = <3300000>;
	enable-active-high;
	gpio = <&pio 55 GPIO_ACTIVE_HIGH>;
	pinctrl-names = "default";
	pinctrl-0 = <&panel_fixed_pins>;
};

&edp_tx {
	status = "okay";

	pinctrl-names = "default";
	pinctrl-0 = <&edptx_pins_default>;

	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		port@0 {
			reg = <0>;
			edp_in: endpoint {
				remote-endpoint = <&dp_intf0_out>;
			};
		};

		port@1 {
			reg = <1>;
			edp_out: endpoint {
				data-lanes = <0 1 2 3>;
				remote-endpoint = <&panel_in>;
			};
		};
	};

	aux-bus {
		panel: panel {
			compatible = "edp-panel";
			power-supply = <&pp3300_disp_x>;
			backlight = <&backlight_lcd0>;
			port {
				panel_in: endpoint {
					remote-endpoint = <&edp_out>;
				};
			};
		};
	};
};

AngeloGioacchino Del Regno (11):
  drm/mediatek: dp: Add missing error checks in
    mtk_dp_parse_capabilities
  drm/mediatek: dp: Move AUX and panel poweron/off sequence to function
  drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer()
  drm/mediatek: dp: Use devm variant of drm_bridge_add()
  drm/mediatek: dp: Move AUX_P0 setting to
    mtk_dp_initialize_aux_settings()
  drm/mediatek: dp: Enable event interrupt only when bridge attached
  drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled
  drm/mediatek: dp: Move PHY registration to new function
  drm/mediatek: dp: Add support for embedded DisplayPort aux-bus
  drm/mediatek: dp: Add .wait_hpd_asserted() for AUX bus
  drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

 drivers/gpu/drm/mediatek/Kconfig  |   1 +
 drivers/gpu/drm/mediatek/mtk_dp.c | 360 ++++++++++++++++++++----------
 2 files changed, 242 insertions(+), 119 deletions(-)

-- 
2.40.1

[PATCH v6 01/11] drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities

[AngeloGioacchino Del Regno]

If reading the RX capabilities fails the training pattern will be set
wrongly: add error checking for drm_dp_read_dpcd_caps() and return if
anything went wrong with it.

While at it, also add a less critical error check when writing to
clear the ESI0 IRQ vector.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 64eee77452c0..c58b775877a3 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1588,7 +1588,9 @@ static int mtk_dp_parse_capabilities(struct mtk_dp *mtk_dp)
 	u8 val;
 	ssize_t ret;
 
-	drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
+	ret = drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
+	if (ret < 0)
+		return ret;
 
 	if (drm_dp_tps4_supported(mtk_dp->rx_cap))
 		mtk_dp->train_info.channel_eq_pattern = DP_TRAINING_PATTERN_4;
@@ -1615,10 +1617,13 @@ static int mtk_dp_parse_capabilities(struct mtk_dp *mtk_dp)
 			return ret == 0 ? -EIO : ret;
 		}
 
-		if (val)
-			drm_dp_dpcd_writeb(&mtk_dp->aux,
-					   DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0,
-					   val);
+		if (val) {
+			ret = drm_dp_dpcd_writeb(&mtk_dp->aux,
+						 DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0,
+						 val);
+			if (ret < 0)
+				return ret;
+		}
 	}
 
 	return 0;
-- 
2.40.1

[PATCH v6 02/11] drm/mediatek: dp: Move AUX and panel poweron/off sequence to function

[AngeloGioacchino Del Regno]

Everytime we run bridge detection and/or EDID read we run a poweron
and poweroff sequence for both the AUX and the panel; moreover, this
is also done when enabling the bridge in the .atomic_enable() callback.

Move this power on/off sequence to a new mtk_dp_aux_panel_poweron()
function as to commonize it.
Note that, before this commit, in mtk_dp_bridge_atomic_enable() only
the AUX was getting powered on but the panel was left powered off if
the DP cable wasn't plugged in while now we unconditionally send a D0
request and this is done for two reasons:
 - First, whether this request fails or not, it takes the same time
   and anyway the DP hardware won't produce any error (or, if it
   does, it's ignorable because it won't block further commands)
 - Second, training the link between a sleeping/standby/unpowered
   display makes little sense.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 76 ++++++++++++-------------------
 1 file changed, 30 insertions(+), 46 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index c58b775877a3..77da0d002e9f 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1251,6 +1251,29 @@ static void mtk_dp_audio_mute(struct mtk_dp *mtk_dp, bool mute)
 			   val[2], AU_TS_CFG_DP_ENC0_P0_MASK);
 }
 
+static void mtk_dp_aux_panel_poweron(struct mtk_dp *mtk_dp, bool pwron)
+{
+	if (pwron) {
+		/* power on aux */
+		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
+				   DP_PWR_STATE_MASK);
+
+		/* power on panel */
+		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
+		usleep_range(2000, 5000);
+	} else {
+		/* power off panel */
+		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
+		usleep_range(2000, 3000);
+
+		/* power off aux */
+		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+				   DP_PWR_STATE_BANDGAP_TPLL,
+				   DP_PWR_STATE_MASK);
+	}
+}
+
 static void mtk_dp_power_enable(struct mtk_dp *mtk_dp)
 {
 	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_RESET_AND_PROBE,
@@ -1941,16 +1964,9 @@ static enum drm_connector_status mtk_dp_bdg_detect(struct drm_bridge *bridge)
 	if (!mtk_dp->train_info.cable_plugged_in)
 		return ret;
 
-	if (!enabled) {
-		/* power on aux */
-		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
-				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
-				   DP_PWR_STATE_MASK);
+	if (!enabled)
+		mtk_dp_aux_panel_poweron(mtk_dp, true);
 
-		/* power on panel */
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
-		usleep_range(2000, 5000);
-	}
 	/*
 	 * Some dongles still source HPD when they do not connect to any
 	 * sink device. To avoid this, we need to read the sink count
@@ -1962,16 +1978,8 @@ static enum drm_connector_status mtk_dp_bdg_detect(struct drm_bridge *bridge)
 	if (DP_GET_SINK_COUNT(sink_count))
 		ret = connector_status_connected;
 
-	if (!enabled) {
-		/* power off panel */
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
-		usleep_range(2000, 3000);
-
-		/* power off aux */
-		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
-				   DP_PWR_STATE_BANDGAP_TPLL,
-				   DP_PWR_STATE_MASK);
-	}
+	if (!enabled)
+		mtk_dp_aux_panel_poweron(mtk_dp, false);
 
 	return ret;
 }
@@ -1987,15 +1995,7 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 
 	if (!enabled) {
 		drm_atomic_bridge_chain_pre_enable(bridge, connector->state->state);
-
-		/* power on aux */
-		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
-				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
-				   DP_PWR_STATE_MASK);
-
-		/* power on panel */
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
-		usleep_range(2000, 5000);
+		mtk_dp_aux_panel_poweron(mtk_dp, true);
 	}
 
 	new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc);
@@ -2015,15 +2015,7 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 	}
 
 	if (!enabled) {
-		/* power off panel */
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
-		usleep_range(2000, 3000);
-
-		/* power off aux */
-		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
-				   DP_PWR_STATE_BANDGAP_TPLL,
-				   DP_PWR_STATE_MASK);
-
+		mtk_dp_aux_panel_poweron(mtk_dp, false);
 		drm_atomic_bridge_chain_post_disable(bridge, connector->state->state);
 	}
 
@@ -2183,15 +2175,7 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 		return;
 	}
 
-	/* power on aux */
-	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
-			   DP_PWR_STATE_BANDGAP_TPLL_LANE,
-			   DP_PWR_STATE_MASK);
-
-	if (mtk_dp->train_info.cable_plugged_in) {
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
-		usleep_range(2000, 5000);
-	}
+	mtk_dp_aux_panel_poweron(mtk_dp, true);
 
 	/* Training */
 	ret = mtk_dp_training(mtk_dp);
-- 
2.40.1

[PATCH v6 03/11] drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer()

[AngeloGioacchino Del Regno]

Change logging from drm_{err,info}() to dev_{err,info}() in functions
mtk_dp_aux_transfer() and mtk_dp_aux_do_transfer(): this will be
essential to avoid getting NULL pointer kernel panics if any kind
of error happens during AUX transfers happening before the bridge
is attached.

This may potentially start happening in a later commit implementing
aux-bus support, as AUX transfers will be triggered from the panel
driver (for EDID) before the mtk-dp bridge gets attached, and it's
done in preparation for the same.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 77da0d002e9f..98f63d8230e4 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -847,7 +847,7 @@ static int mtk_dp_aux_do_transfer(struct mtk_dp *mtk_dp, bool is_read, u8 cmd,
 		u32 phy_status = mtk_dp_read(mtk_dp, MTK_DP_AUX_P0_3628) &
 				 AUX_RX_PHY_STATE_AUX_TX_P0_MASK;
 		if (phy_status != AUX_RX_PHY_STATE_AUX_TX_P0_RX_IDLE) {
-			drm_err(mtk_dp->drm_dev,
+			dev_err(mtk_dp->dev,
 				"AUX Rx Aux hang, need SW reset\n");
 			return -EIO;
 		}
@@ -2054,7 +2054,7 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
 		is_read = true;
 		break;
 	default:
-		drm_err(mtk_aux->drm_dev, "invalid aux cmd = %d\n",
+		dev_err(mtk_dp->dev, "invalid aux cmd = %d\n",
 			msg->request);
 		ret = -EINVAL;
 		goto err;
@@ -2070,7 +2070,7 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
 					     to_access, &msg->reply);
 
 		if (ret) {
-			drm_info(mtk_dp->drm_dev,
+			dev_info(mtk_dp->dev,
 				 "Failed to do AUX transfer: %d\n", ret);
 			goto err;
 		}
-- 
2.40.1

[PATCH v6 04/11] drm/mediatek: dp: Use devm variant of drm_bridge_add()

[AngeloGioacchino Del Regno]

In preparation for adding support for aux-bus, which will add a code
path that may fail after the drm_bridge_add() call, change that to
devm_drm_bridge_add() to simplify failure paths later.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 98f63d8230e4..fc6cabf5370b 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2552,7 +2552,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
 		DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
 	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
 
-	drm_bridge_add(&mtk_dp->bridge);
+	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add bridge\n");
 
 	mtk_dp->need_debounce = true;
 	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
@@ -2570,7 +2572,6 @@ static int mtk_dp_remove(struct platform_device *pdev)
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	del_timer_sync(&mtk_dp->debounce_timer);
-	drm_bridge_remove(&mtk_dp->bridge);
 	platform_device_unregister(mtk_dp->phy_dev);
 	if (mtk_dp->audio_pdev)
 		platform_device_unregister(mtk_dp->audio_pdev);
-- 
2.40.1

[PATCH v6 05/11] drm/mediatek: dp: Move AUX_P0 setting to mtk_dp_initialize_aux_settings()

[AngeloGioacchino Del Regno]

Move the register write to MTK_DP_AUX_P0_3690 to set the AUX reply mode
to function mtk_dp_initialize_aux_settings(), as this is effectively
part of the DPTX AUX setup sequence.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index fc6cabf5370b..e8d3bf310608 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1009,6 +1009,11 @@ static void mtk_dp_initialize_aux_settings(struct mtk_dp *mtk_dp)
 	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_37C8,
 			   MTK_ATOP_EN_AUX_TX_P0,
 			   MTK_ATOP_EN_AUX_TX_P0);
+
+	/* Set complete reply mode for AUX */
+	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_3690,
+			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0,
+			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0);
 }
 
 static void mtk_dp_initialize_digital_settings(struct mtk_dp *mtk_dp)
@@ -1826,10 +1831,6 @@ static void mtk_dp_init_port(struct mtk_dp *mtk_dp)
 	mtk_dp_initialize_settings(mtk_dp);
 	mtk_dp_initialize_aux_settings(mtk_dp);
 	mtk_dp_initialize_digital_settings(mtk_dp);
-
-	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_3690,
-			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0,
-			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0);
 	mtk_dp_initialize_hpd_detect_settings(mtk_dp);
 
 	mtk_dp_digital_sw_reset(mtk_dp);
-- 
2.40.1

[PATCH v6 06/11] drm/mediatek: dp: Enable event interrupt only when bridge attached

[AngeloGioacchino Del Regno]

It is useless and error-prone to enable the DisplayPort event interrupt
before finishing to probe and install the driver, as the DP training
cannot happen before the entire pipeline is correctly set up, as the
interrupt handler also requires the full hardware to be initialized by
mtk_dp_bridge_attach().

Anyway, depending in which state the controller is left from the
bootloader, this may cause an interrupt storm and consequently hang
the kernel during boot, so, avoid enabling the interrupt until we
reach a clean state by adding the IRQ_NOAUTOEN flag before requesting
it at probe time and manage the enablement of the ISR in the .attach()
and .detach() handlers for the DP bridge.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index e8d3bf310608..83e55f8dc84a 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -100,6 +100,7 @@ struct mtk_dp_efuse_fmt {
 struct mtk_dp {
 	bool enabled;
 	bool need_debounce;
+	int irq;
 	u8 max_lanes;
 	u8 max_linkrate;
 	u8 rx_cap[DP_RECEIVER_CAP_SIZE];
@@ -2141,6 +2142,8 @@ static int mtk_dp_bridge_attach(struct drm_bridge *bridge,
 
 	mtk_dp->drm_dev = bridge->dev;
 
+	irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+	enable_irq(mtk_dp->irq);
 	mtk_dp_hwirq_enable(mtk_dp, true);
 
 	return 0;
@@ -2157,6 +2160,7 @@ static void mtk_dp_bridge_detach(struct drm_bridge *bridge)
 	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 
 	mtk_dp_hwirq_enable(mtk_dp, false);
+	disable_irq(mtk_dp->irq);
 	mtk_dp->drm_dev = NULL;
 	mtk_dp_poweroff(mtk_dp);
 	drm_dp_aux_unregister(&mtk_dp->aux);
@@ -2475,7 +2479,7 @@ static int mtk_dp_probe(struct platform_device *pdev)
 {
 	struct mtk_dp *mtk_dp;
 	struct device *dev = &pdev->dev;
-	int ret, irq_num;
+	int ret;
 
 	mtk_dp = devm_kzalloc(dev, sizeof(*mtk_dp), GFP_KERNEL);
 	if (!mtk_dp)
@@ -2484,9 +2488,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	mtk_dp->dev = dev;
 	mtk_dp->data = (struct mtk_dp_data *)of_device_get_match_data(dev);
 
-	irq_num = platform_get_irq(pdev, 0);
-	if (irq_num < 0)
-		return dev_err_probe(dev, irq_num,
+	mtk_dp->irq = platform_get_irq(pdev, 0);
+	if (mtk_dp->irq < 0)
+		return dev_err_probe(dev, mtk_dp->irq,
 				     "failed to request dp irq resource\n");
 
 	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
@@ -2507,7 +2511,8 @@ static int mtk_dp_probe(struct platform_device *pdev)
 
 	spin_lock_init(&mtk_dp->irq_thread_lock);
 
-	ret = devm_request_threaded_irq(dev, irq_num, mtk_dp_hpd_event,
+	irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+	ret = devm_request_threaded_irq(dev, mtk_dp->irq, mtk_dp_hpd_event,
 					mtk_dp_hpd_event_thread,
 					IRQ_TYPE_LEVEL_HIGH, dev_name(dev),
 					mtk_dp);
-- 
2.40.1

[PATCH v6 07/11] drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled

[AngeloGioacchino Del Regno]

If a controller (usually, eDP!) does not support audio, or audio is not
enabled because the endpoint has no audio support, it's useless to lock
a mutex only to unlock it right after because there's no .plugged_cb().

Check if the audio is supported and enabled before locking the mutex in
mtk_dp_update_plugged_status(): if not, we simply return immediately.

While at it, since the update_plugged_status_lock mutex would not be
used if the controller doesn't support audio at all, initialize it
only if `audio_supported` is true.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 83e55f8dc84a..c1d1a882f1db 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1948,6 +1948,9 @@ static int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
 
 static void mtk_dp_update_plugged_status(struct mtk_dp *mtk_dp)
 {
+	if (!mtk_dp->data->audio_supported || !mtk_dp->audio_enable)
+		return;
+
 	mutex_lock(&mtk_dp->update_plugged_status_lock);
 	if (mtk_dp->plugged_cb && mtk_dp->codec_dev)
 		mtk_dp->plugged_cb(mtk_dp->codec_dev,
@@ -2520,11 +2523,11 @@ static int mtk_dp_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, ret,
 				     "failed to request mediatek dptx irq\n");
 
-	mutex_init(&mtk_dp->update_plugged_status_lock);
-
 	platform_set_drvdata(pdev, mtk_dp);
 
 	if (mtk_dp->data->audio_supported) {
+		mutex_init(&mtk_dp->update_plugged_status_lock);
+
 		ret = mtk_dp_register_audio_driver(dev);
 		if (ret) {
 			dev_err(dev, "Failed to register audio driver: %d\n",
-- 
2.40.1

[PATCH v6 08/11] drm/mediatek: dp: Move PHY registration to new function

[AngeloGioacchino Del Regno]

In preparation for adding support for eDP, move the PHY registration
code to a new mtk_dp_register_phy() function for better readability.

This commit brings no functional changes.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 43 +++++++++++++++++++------------
 1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index c1d1a882f1db..1b4219e6a00b 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2478,6 +2478,29 @@ static int mtk_dp_register_audio_driver(struct device *dev)
 	return PTR_ERR_OR_ZERO(mtk_dp->audio_pdev);
 }
 
+static int mtk_dp_register_phy(struct mtk_dp *mtk_dp)
+{
+	struct device *dev = mtk_dp->dev;
+
+	mtk_dp->phy_dev = platform_device_register_data(dev, "mediatek-dp-phy",
+							PLATFORM_DEVID_AUTO,
+							&mtk_dp->regs,
+							sizeof(struct regmap *));
+	if (IS_ERR(mtk_dp->phy_dev))
+		return dev_err_probe(dev, PTR_ERR(mtk_dp->phy_dev),
+				     "Failed to create device mediatek-dp-phy\n");
+
+	mtk_dp_get_calibration_data(mtk_dp);
+
+	mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp");
+	if (IS_ERR(mtk_dp->phy)) {
+		platform_device_unregister(mtk_dp->phy_dev);
+		return dev_err_probe(dev, PTR_ERR(mtk_dp->phy), "Failed to get phy\n");
+	}
+
+	return 0;
+}
+
 static int mtk_dp_probe(struct platform_device *pdev)
 {
 	struct mtk_dp *mtk_dp;
@@ -2536,23 +2559,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
 		}
 	}
 
-	mtk_dp->phy_dev = platform_device_register_data(dev, "mediatek-dp-phy",
-							PLATFORM_DEVID_AUTO,
-							&mtk_dp->regs,
-							sizeof(struct regmap *));
-	if (IS_ERR(mtk_dp->phy_dev))
-		return dev_err_probe(dev, PTR_ERR(mtk_dp->phy_dev),
-				     "Failed to create device mediatek-dp-phy\n");
-
-	mtk_dp_get_calibration_data(mtk_dp);
-
-	mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp");
-
-	if (IS_ERR(mtk_dp->phy)) {
-		platform_device_unregister(mtk_dp->phy_dev);
-		return dev_err_probe(dev, PTR_ERR(mtk_dp->phy),
-				     "Failed to get phy\n");
-	}
+	ret = mtk_dp_register_phy(mtk_dp);
+	if (ret)
+		return ret;
 
 	mtk_dp->bridge.funcs = &mtk_dp_bridge_funcs;
 	mtk_dp->bridge.of_node = dev->of_node;
-- 
2.40.1

[PATCH v6 09/11] drm/mediatek: dp: Add support for embedded DisplayPort aux-bus

[AngeloGioacchino Del Regno]

For the eDP case we can support using aux-bus on MediaTek DP: this
gives us the possibility to declare our panel as generic "panel-edp"
which will automatically configure the timings and available modes
via the EDID that we read from it.

To do this, move the panel parsing at the end of the probe function
so that the hardware is initialized beforehand and also initialize
the DPTX AUX block and power both on as, when we populate the
aux-bus, the panel driver will trigger an EDID read to perform
panel detection.

Last but not least, since now the AUX transfers can happen in the
separated aux-bus, it was necessary to add an exclusion for the
cable_plugged_in check in `mtk_dp_aux_transfer()` and the easiest
way to do this is to simply ignore checking that when the bridge
type is eDP.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/Kconfig  |  1 +
 drivers/gpu/drm/mediatek/mtk_dp.c | 84 ++++++++++++++++++++++++++++---
 2 files changed, 79 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
index b451dee64d34..76cab28e010c 100644
--- a/drivers/gpu/drm/mediatek/Kconfig
+++ b/drivers/gpu/drm/mediatek/Kconfig
@@ -26,6 +26,7 @@ config DRM_MEDIATEK_DP
 	select PHY_MTK_DP
 	select DRM_DISPLAY_HELPER
 	select DRM_DISPLAY_DP_HELPER
+	select DRM_DP_AUX_BUS
 	help
 	  DRM/KMS Display Port driver for MediaTek SoCs.
 
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 1b4219e6a00b..acdd457b5449 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2022 BayLibre
  */
 
+#include <drm/display/drm_dp_aux_bus.h>
 #include <drm/display/drm_dp.h>
 #include <drm/display/drm_dp_helper.h>
 #include <drm/drm_atomic_helper.h>
@@ -1313,9 +1314,11 @@ static void mtk_dp_power_disable(struct mtk_dp *mtk_dp)
 
 static void mtk_dp_initialize_priv_data(struct mtk_dp *mtk_dp)
 {
+	bool plugged_in = (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP);
+
 	mtk_dp->train_info.link_rate = DP_LINK_BW_5_4;
 	mtk_dp->train_info.lane_count = mtk_dp->max_lanes;
-	mtk_dp->train_info.cable_plugged_in = false;
+	mtk_dp->train_info.cable_plugged_in = plugged_in;
 
 	mtk_dp->info.format = DP_PIXELFORMAT_RGB;
 	memset(&mtk_dp->info.vm, 0, sizeof(struct videomode));
@@ -1617,6 +1620,16 @@ static int mtk_dp_parse_capabilities(struct mtk_dp *mtk_dp)
 	u8 val;
 	ssize_t ret;
 
+	/*
+	 * If we're eDP and capabilities were already parsed we can skip
+	 * reading again because eDP panels aren't hotpluggable hence the
+	 * caps and training information won't ever change in a boot life
+	 */
+	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP &&
+	    mtk_dp->rx_cap[DP_MAX_LINK_RATE] &&
+	    mtk_dp->train_info.sink_ssc)
+		return 0;
+
 	ret = drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
 	if (ret < 0)
 		return ret;
@@ -2030,15 +2043,14 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
 				   struct drm_dp_aux_msg *msg)
 {
-	struct mtk_dp *mtk_dp;
+	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
 	bool is_read;
 	u8 request;
 	size_t accessed_bytes = 0;
 	int ret;
 
-	mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
-
-	if (!mtk_dp->train_info.cable_plugged_in) {
+	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP &&
+	    !mtk_dp->train_info.cable_plugged_in) {
 		ret = -EAGAIN;
 		goto err;
 	}
@@ -2501,6 +2513,28 @@ static int mtk_dp_register_phy(struct mtk_dp *mtk_dp)
 	return 0;
 }
 
+static int mtk_dp_edp_link_panel(struct drm_dp_aux *mtk_aux)
+{
+	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
+	struct device *dev = mtk_aux->dev;
+	int ret;
+
+	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
+
+	/* Power off the DP and AUX: either detection is done, or no panel present */
+	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+			   DP_PWR_STATE_BANDGAP_TPLL,
+			   DP_PWR_STATE_MASK);
+	mtk_dp_power_disable(mtk_dp);
+
+	if (IS_ERR(mtk_dp->next_bridge)) {
+		ret = PTR_ERR(mtk_dp->next_bridge);
+		mtk_dp->next_bridge = NULL;
+		return ret;
+	}
+	return 0;
+}
+
 static int mtk_dp_probe(struct platform_device *pdev)
 {
 	struct mtk_dp *mtk_dp;
@@ -2531,9 +2565,10 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to parse dt\n");
 
-	drm_dp_aux_init(&mtk_dp->aux);
 	mtk_dp->aux.name = "aux_mtk_dp";
+	mtk_dp->aux.dev = dev;
 	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
+	drm_dp_aux_init(&mtk_dp->aux);
 
 	spin_lock_init(&mtk_dp->irq_thread_lock);
 
@@ -2577,6 +2612,43 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	mtk_dp->need_debounce = true;
 	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
 
+	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
+		/*
+		 * Set the data lanes to idle in case the bootloader didn't
+		 * properly close the eDP port to avoid stalls and then
+		 * reinitialize, reset and power on the AUX block.
+		 */
+		mtk_dp_set_idle_pattern(mtk_dp, true);
+		mtk_dp_initialize_aux_settings(mtk_dp);
+		mtk_dp_power_enable(mtk_dp);
+
+		/*
+		 * Power on the AUX to allow reading the EDID from aux-bus:
+		 * please note that it is necessary to call power off in the
+		 * .done_probing() callback (mtk_dp_edp_link_panel), as only
+		 * there we can safely assume that we finished reading EDID.
+		 */
+		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
+				   DP_PWR_STATE_MASK);
+
+		ret = devm_of_dp_aux_populate_bus(&mtk_dp->aux, mtk_dp_edp_link_panel);
+		if (ret) {
+			/* -ENODEV this means that the panel is not on the aux-bus */
+			if (ret == -ENODEV) {
+				ret = mtk_dp_edp_link_panel(&mtk_dp->aux);
+				if (ret)
+					return ret;
+			} else {
+				mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+						   DP_PWR_STATE_BANDGAP_TPLL,
+						   DP_PWR_STATE_MASK);
+				mtk_dp_power_disable(mtk_dp);
+				return ret;
+			}
+		}
+	}
+
 	pm_runtime_enable(dev);
 	pm_runtime_get_sync(dev);
 
-- 
2.40.1

[PATCH v6 10/11] drm/mediatek: dp: Add .wait_hpd_asserted() for AUX bus

[AngeloGioacchino Del Regno]

In order to support usecases in which the panel regulator can be
switched on and off to save power, and usecases in which the panel
regulator is off at boot, add a .wait_hpd_asserted() callback for
the AUX bus: this will make sure to wait until the panel is fully
ready after power-on before trying to communicate with it.

Also, parse the eDP display capabilities in that callback, so that
we can also avoid using the .get_edid() callback from this bridge.

Since at this point the hpd machinery is performed in the new hpd
callback and the detection and edid reading are done outside of
this driver, assign the DRM_BRIDGE_OP_{DETECT, EDID, HPD} ops and
register the bridge unconditionally at probe time only if we are
probing full DisplayPort and not eDP while, for the latter, we
register the bridge in the .done_probing() callback and only if
the panel was found and triggered HPD.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 45 ++++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index acdd457b5449..e74295ba9707 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1920,6 +1920,31 @@ static irqreturn_t mtk_dp_hpd_event(int hpd, void *dev)
 	return IRQ_WAKE_THREAD;
 }
 
+static int mtk_dp_wait_hpd_asserted(struct drm_dp_aux *mtk_aux, unsigned long wait_us)
+{
+	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
+	u32 val;
+	int ret;
+
+	ret = regmap_read_poll_timeout(mtk_dp->regs, MTK_DP_TRANS_P0_3414,
+				       val, !!(val & HPD_DB_DP_TRANS_P0_MASK),
+				       wait_us / 100, wait_us);
+	if (ret) {
+		mtk_dp->train_info.cable_plugged_in = false;
+		return ret;
+	}
+
+	mtk_dp->train_info.cable_plugged_in = true;
+
+	ret = mtk_dp_parse_capabilities(mtk_dp);
+	if (ret) {
+		drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
 			   struct platform_device *pdev)
 {
@@ -2532,6 +2557,12 @@ static int mtk_dp_edp_link_panel(struct drm_dp_aux *mtk_aux)
 		mtk_dp->next_bridge = NULL;
 		return ret;
 	}
+
+	/* For eDP, we add the bridge only if the panel was found */
+	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
@@ -2568,6 +2599,7 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	mtk_dp->aux.name = "aux_mtk_dp";
 	mtk_dp->aux.dev = dev;
 	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
+	mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
 	drm_dp_aux_init(&mtk_dp->aux);
 
 	spin_lock_init(&mtk_dp->irq_thread_lock);
@@ -2600,15 +2632,8 @@ static int mtk_dp_probe(struct platform_device *pdev)
 
 	mtk_dp->bridge.funcs = &mtk_dp_bridge_funcs;
 	mtk_dp->bridge.of_node = dev->of_node;
-
-	mtk_dp->bridge.ops =
-		DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
 	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
 
-	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
-	if (ret)
-		return dev_err_probe(dev, ret, "Failed to add bridge\n");
-
 	mtk_dp->need_debounce = true;
 	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
 
@@ -2647,6 +2672,12 @@ static int mtk_dp_probe(struct platform_device *pdev)
 				return ret;
 			}
 		}
+	} else {
+		mtk_dp->bridge.ops = DRM_BRIDGE_OP_DETECT |
+				     DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
+		ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to add bridge\n");
 	}
 
 	pm_runtime_enable(dev);
-- 
2.40.1

[PATCH v6 11/11] drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

[AngeloGioacchino Del Regno]

The interrupt handler for HPD is useful only if a display is actually
supposed to be hotpluggable, as that manages the machinery to perform
cable (un)plug detection, debouncing and setup for re-training.

Since eDP panels are not supposed to be hotpluggable we can avoid
using the HPD interrupts altogether and rely on HPD polling only
for the suspend/resume case, saving us some spinlocking action and
the overhead of interrupts firing at every suspend/resume cycle,
achieving a faster (even if just slightly) display resume.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 81 ++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 35 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index e74295ba9707..c06fcc7318e7 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2182,9 +2182,11 @@ static int mtk_dp_bridge_attach(struct drm_bridge *bridge,
 
 	mtk_dp->drm_dev = bridge->dev;
 
-	irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
-	enable_irq(mtk_dp->irq);
-	mtk_dp_hwirq_enable(mtk_dp, true);
+	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
+		irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+		enable_irq(mtk_dp->irq);
+		mtk_dp_hwirq_enable(mtk_dp, true);
+	}
 
 	return 0;
 
@@ -2199,8 +2201,10 @@ static void mtk_dp_bridge_detach(struct drm_bridge *bridge)
 {
 	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 
-	mtk_dp_hwirq_enable(mtk_dp, false);
-	disable_irq(mtk_dp->irq);
+	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
+		mtk_dp_hwirq_enable(mtk_dp, false);
+		disable_irq(mtk_dp->irq);
+	}
 	mtk_dp->drm_dev = NULL;
 	mtk_dp_poweroff(mtk_dp);
 	drm_dp_aux_unregister(&mtk_dp->aux);
@@ -2579,40 +2583,44 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	mtk_dp->dev = dev;
 	mtk_dp->data = (struct mtk_dp_data *)of_device_get_match_data(dev);
 
-	mtk_dp->irq = platform_get_irq(pdev, 0);
-	if (mtk_dp->irq < 0)
-		return dev_err_probe(dev, mtk_dp->irq,
-				     "failed to request dp irq resource\n");
-
-	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
-	if (IS_ERR(mtk_dp->next_bridge) &&
-	    PTR_ERR(mtk_dp->next_bridge) == -ENODEV)
-		mtk_dp->next_bridge = NULL;
-	else if (IS_ERR(mtk_dp->next_bridge))
-		return dev_err_probe(dev, PTR_ERR(mtk_dp->next_bridge),
-				     "Failed to get bridge\n");
-
 	ret = mtk_dp_dt_parse(mtk_dp, pdev);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to parse dt\n");
 
+	/*
+	 * Request the interrupt and install service routine only if we are
+	 * on full DisplayPort.
+	 * For eDP, polling the HPD instead is more convenient because we
+	 * don't expect any (un)plug events during runtime, hence we can
+	 * avoid some locking.
+	 */
+	if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP) {
+		mtk_dp->irq = platform_get_irq(pdev, 0);
+		if (mtk_dp->irq < 0)
+			return dev_err_probe(dev, mtk_dp->irq,
+					     "failed to request dp irq resource\n");
+
+		spin_lock_init(&mtk_dp->irq_thread_lock);
+
+		irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+		ret = devm_request_threaded_irq(dev, mtk_dp->irq, mtk_dp_hpd_event,
+						mtk_dp_hpd_event_thread,
+						IRQ_TYPE_LEVEL_HIGH, dev_name(dev),
+						mtk_dp);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "failed to request mediatek dptx irq\n");
+
+		mtk_dp->need_debounce = true;
+		timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
+	}
+
 	mtk_dp->aux.name = "aux_mtk_dp";
 	mtk_dp->aux.dev = dev;
 	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
 	mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
 	drm_dp_aux_init(&mtk_dp->aux);
 
-	spin_lock_init(&mtk_dp->irq_thread_lock);
-
-	irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
-	ret = devm_request_threaded_irq(dev, mtk_dp->irq, mtk_dp_hpd_event,
-					mtk_dp_hpd_event_thread,
-					IRQ_TYPE_LEVEL_HIGH, dev_name(dev),
-					mtk_dp);
-	if (ret)
-		return dev_err_probe(dev, ret,
-				     "failed to request mediatek dptx irq\n");
-
 	platform_set_drvdata(pdev, mtk_dp);
 
 	if (mtk_dp->data->audio_supported) {
@@ -2634,9 +2642,6 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	mtk_dp->bridge.of_node = dev->of_node;
 	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
 
-	mtk_dp->need_debounce = true;
-	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
-
 	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
 		/*
 		 * Set the data lanes to idle in case the bootloader didn't
@@ -2647,6 +2652,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
 		mtk_dp_initialize_aux_settings(mtk_dp);
 		mtk_dp_power_enable(mtk_dp);
 
+		/* Disable HW interrupts: we don't need any for eDP */
+		mtk_dp_hwirq_enable(mtk_dp, false);
+
 		/*
 		 * Power on the AUX to allow reading the EDID from aux-bus:
 		 * please note that it is necessary to call power off in the
@@ -2692,7 +2700,8 @@ static int mtk_dp_remove(struct platform_device *pdev)
 
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
-	del_timer_sync(&mtk_dp->debounce_timer);
+	if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP)
+		del_timer_sync(&mtk_dp->debounce_timer);
 	platform_device_unregister(mtk_dp->phy_dev);
 	if (mtk_dp->audio_pdev)
 		platform_device_unregister(mtk_dp->audio_pdev);
@@ -2706,7 +2715,8 @@ static int mtk_dp_suspend(struct device *dev)
 	struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
 
 	mtk_dp_power_disable(mtk_dp);
-	mtk_dp_hwirq_enable(mtk_dp, false);
+	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
+		mtk_dp_hwirq_enable(mtk_dp, false);
 	pm_runtime_put_sync(dev);
 
 	return 0;
@@ -2718,7 +2728,8 @@ static int mtk_dp_resume(struct device *dev)
 
 	pm_runtime_get_sync(dev);
 	mtk_dp_init_port(mtk_dp);
-	mtk_dp_hwirq_enable(mtk_dp, true);
+	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
+		mtk_dp_hwirq_enable(mtk_dp, true);
 	mtk_dp_power_enable(mtk_dp);
 
 	return 0;
-- 
2.40.1

Re: [PATCH v6 02/11] drm/mediatek: dp: Move AUX and panel poweron/off sequence to function

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Everytime we run bridge detection and/or EDID read we run a poweron
> and poweroff sequence for both the AUX and the panel; moreover, this
> is also done when enabling the bridge in the .atomic_enable()
> callback.
> 
> Move this power on/off sequence to a new mtk_dp_aux_panel_poweron()
> function as to commonize it.
> Note that, before this commit, in mtk_dp_bridge_atomic_enable() only
> the AUX was getting powered on but the panel was left powered off if
> the DP cable wasn't plugged in while now we unconditionally send a D0
> request and this is done for two reasons:
>  - First, whether this request fails or not, it takes the same time
>    and anyway the DP hardware won't produce any error (or, if it
>    does, it's ignorable because it won't block further commands)
>  - Second, training the link between a sleeping/standby/unpowered
>    display makes little sense.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> Tested-by: Chen-Yu Tsai <wenst@chromium.org>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 76 ++++++++++++-----------------
> --
>  1 file changed, 30 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index c58b775877a3..77da0d002e9f 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1251,6 +1251,29 @@ static void mtk_dp_audio_mute(struct mtk_dp
> *mtk_dp, bool mute)
>  			   val[2], AU_TS_CFG_DP_ENC0_P0_MASK);
>  }
>  
> +static void mtk_dp_aux_panel_poweron(struct mtk_dp *mtk_dp, bool
> pwron)
> +{
> +	if (pwron) {
> +		/* power on aux */
> +		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> +				   DP_PWR_STATE_MASK);
> +
> +		/* power on panel */
> +		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D0);
> +		usleep_range(2000, 5000);
> +	} else {
> +		/* power off panel */
> +		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D3);
> +		usleep_range(2000, 3000);
> +
> +		/* power off aux */
> +		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +				   DP_PWR_STATE_BANDGAP_TPLL,
> +				   DP_PWR_STATE_MASK);
> +	}
> +}
> +
>  static void mtk_dp_power_enable(struct mtk_dp *mtk_dp)
>  {
>  	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_RESET_AND_PROBE,
> @@ -1941,16 +1964,9 @@ static enum drm_connector_status
> mtk_dp_bdg_detect(struct drm_bridge *bridge)
>  	if (!mtk_dp->train_info.cable_plugged_in)
>  		return ret;
>  
> -	if (!enabled) {
> -		/* power on aux */
> -		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> -				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> -				   DP_PWR_STATE_MASK);
> +	if (!enabled)
> +		mtk_dp_aux_panel_poweron(mtk_dp, true);
>  
> -		/* power on panel */
> -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D0);
> -		usleep_range(2000, 5000);
> -	}
>  	/*
>  	 * Some dongles still source HPD when they do not connect to
> any
>  	 * sink device. To avoid this, we need to read the sink count
> @@ -1962,16 +1978,8 @@ static enum drm_connector_status
> mtk_dp_bdg_detect(struct drm_bridge *bridge)
>  	if (DP_GET_SINK_COUNT(sink_count))
>  		ret = connector_status_connected;
>  
> -	if (!enabled) {
> -		/* power off panel */
> -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D3);
> -		usleep_range(2000, 3000);
> -
> -		/* power off aux */
> -		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> -				   DP_PWR_STATE_BANDGAP_TPLL,
> -				   DP_PWR_STATE_MASK);
> -	}
> +	if (!enabled)
> +		mtk_dp_aux_panel_poweron(mtk_dp, false);
>  
>  	return ret;
>  }
> @@ -1987,15 +1995,7 @@ static struct edid *mtk_dp_get_edid(struct
> drm_bridge *bridge,
>  
>  	if (!enabled) {
>  		drm_atomic_bridge_chain_pre_enable(bridge, connector-
> >state->state);
> -
> -		/* power on aux */
> -		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> -				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> -				   DP_PWR_STATE_MASK);
> -
> -		/* power on panel */
> -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D0);
> -		usleep_range(2000, 5000);
> +		mtk_dp_aux_panel_poweron(mtk_dp, true);
>  	}
>  
>  	new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc);
> @@ -2015,15 +2015,7 @@ static struct edid *mtk_dp_get_edid(struct
> drm_bridge *bridge,
>  	}
>  
>  	if (!enabled) {
> -		/* power off panel */
> -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D3);
> -		usleep_range(2000, 3000);
> -
> -		/* power off aux */
> -		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> -				   DP_PWR_STATE_BANDGAP_TPLL,
> -				   DP_PWR_STATE_MASK);
> -
> +		mtk_dp_aux_panel_poweron(mtk_dp, false);
>  		drm_atomic_bridge_chain_post_disable(bridge, connector-
> >state->state);
>  	}
>  
> @@ -2183,15 +2175,7 @@ static void mtk_dp_bridge_atomic_enable(struct
> drm_bridge *bridge,
>  		return;
>  	}
>  
> -	/* power on aux */
> -	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> -			   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> -			   DP_PWR_STATE_MASK);
> -
> -	if (mtk_dp->train_info.cable_plugged_in) {
> -		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> DP_SET_POWER_D0);
> -		usleep_range(2000, 5000);
> -	}
> +	mtk_dp_aux_panel_poweron(mtk_dp, true);
>  
>  	/* Training */
>  	ret = mtk_dp_training(mtk_dp);
> -- 
> 2.40.1

Re: [PATCH v6 01/11] drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  If reading the RX capabilities fails the training pattern will be
> set
> wrongly: add error checking for drm_dp_read_dpcd_caps() and return if
> anything went wrong with it.
> 
> While at it, also add a less critical error check when writing to
> clear the ESI0 IRQ vector.

Reviwed-by: CK Hu <ck.hu@mediatek.com>

> 
> Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort
> driver")
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 64eee77452c0..c58b775877a3 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1588,7 +1588,9 @@ static int mtk_dp_parse_capabilities(struct
> mtk_dp *mtk_dp)
>  	u8 val;
>  	ssize_t ret;
>  
> -	drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
> +	ret = drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
> +	if (ret < 0)
> +		return ret;
>  
>  	if (drm_dp_tps4_supported(mtk_dp->rx_cap))
>  		mtk_dp->train_info.channel_eq_pattern =
> DP_TRAINING_PATTERN_4;
> @@ -1615,10 +1617,13 @@ static int mtk_dp_parse_capabilities(struct
> mtk_dp *mtk_dp)
>  			return ret == 0 ? -EIO : ret;
>  		}
>  
> -		if (val)
> -			drm_dp_dpcd_writeb(&mtk_dp->aux,
> -					   DP_DEVICE_SERVICE_IRQ_VECTOR
> _ESI0,
> -					   val);
> +		if (val) {
> +			ret = drm_dp_dpcd_writeb(&mtk_dp->aux,
> +						 DP_DEVICE_SERVICE_IRQ_
> VECTOR_ESI0,
> +						 val);
> +			if (ret < 0)
> +				return ret;
> +		}
>  	}
>  
>  	return 0;
> -- 
> 2.40.1

Re: [PATCH v6 03/11] drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer()

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Change logging from drm_{err,info}() to dev_{err,info}() in
> functions
> mtk_dp_aux_transfer() and mtk_dp_aux_do_transfer(): this will be
> essential to avoid getting NULL pointer kernel panics if any kind
> of error happens during AUX transfers happening before the bridge
> is attached.
> 
> This may potentially start happening in a later commit implementing
> aux-bus support, as AUX transfers will be triggered from the panel
> driver (for EDID) before the mtk-dp bridge gets attached, and it's
> done in preparation for the same.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> Tested-by: Chen-Yu Tsai <wenst@chromium.org>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 77da0d002e9f..98f63d8230e4 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -847,7 +847,7 @@ static int mtk_dp_aux_do_transfer(struct mtk_dp
> *mtk_dp, bool is_read, u8 cmd,
>  		u32 phy_status = mtk_dp_read(mtk_dp,
> MTK_DP_AUX_P0_3628) &
>  				 AUX_RX_PHY_STATE_AUX_TX_P0_MASK;
>  		if (phy_status != AUX_RX_PHY_STATE_AUX_TX_P0_RX_IDLE) {
> -			drm_err(mtk_dp->drm_dev,
> +			dev_err(mtk_dp->dev,
>  				"AUX Rx Aux hang, need SW reset\n");
>  			return -EIO;
>  		}
> @@ -2054,7 +2054,7 @@ static ssize_t mtk_dp_aux_transfer(struct
> drm_dp_aux *mtk_aux,
>  		is_read = true;
>  		break;
>  	default:
> -		drm_err(mtk_aux->drm_dev, "invalid aux cmd = %d\n",
> +		dev_err(mtk_dp->dev, "invalid aux cmd = %d\n",
>  			msg->request);
>  		ret = -EINVAL;
>  		goto err;
> @@ -2070,7 +2070,7 @@ static ssize_t mtk_dp_aux_transfer(struct
> drm_dp_aux *mtk_aux,
>  					     to_access, &msg->reply);
>  
>  		if (ret) {
> -			drm_info(mtk_dp->drm_dev,
> +			dev_info(mtk_dp->dev,
>  				 "Failed to do AUX transfer: %d\n",
> ret);
>  			goto err;
>  		}
> -- 
> 2.40.1

Re: [PATCH v6 04/11] drm/mediatek: dp: Use devm variant of drm_bridge_add()

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  In preparation for adding support for aux-bus, which will add a code
> path that may fail after the drm_bridge_add() call, change that to
> devm_drm_bridge_add() to simplify failure paths later.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> Tested-by: Chen-Yu Tsai <wenst@chromium.org>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 98f63d8230e4..fc6cabf5370b 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -2552,7 +2552,9 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  		DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
> DRM_BRIDGE_OP_HPD;
>  	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
>  
> -	drm_bridge_add(&mtk_dp->bridge);
> +	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to add
> bridge\n");
>  
>  	mtk_dp->need_debounce = true;
>  	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
> @@ -2570,7 +2572,6 @@ static int mtk_dp_remove(struct platform_device
> *pdev)
>  	pm_runtime_put(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  	del_timer_sync(&mtk_dp->debounce_timer);
> -	drm_bridge_remove(&mtk_dp->bridge);
>  	platform_device_unregister(mtk_dp->phy_dev);
>  	if (mtk_dp->audio_pdev)
>  		platform_device_unregister(mtk_dp->audio_pdev);
> -- 
> 2.40.1

Re: [PATCH v6 00/11] MediaTek DisplayPort: support eDP and aux-bus

[Chen-Yu Tsai]

On Mon, Jul 17, 2023 at 10:14 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> Changes in v6:
>  - Added some previously missing error checking (patch [01/11])
>  - Added error checks for devm_drm_bridge_add()
>  - Made sure that cable_plugged_in is set to false if HPD assertion
>    polling fails (timeout)
>  - Support panel as module (tested with panel-edp on MT8195 Tomato)
>  - Rebased over next-20230717

Whole series is

Tested-by: Chen-Yu Tsai <wenst@chromium.org>

With panel-edp builtin & as a module, and tested external display,
all on MT8195 Tomato.

Thanks!

> Changes in v5:
>  - Added .wait_hpd_asserted() callback for aux-bus
>  - Avoid enabling and registering HPD interrupt + handlers for
>    eDP case only (keeps HPD interrupts enabled for full DP case)
>  - Support not always-on eDP panels (boot with regulator off,
>    suspend with regulator off) for power saving in PM suspend.
>
> Changes in v4:
>  - Set data lanes to idle to prevent stalls if bootloader didn't
>    properly close the eDP port
>  - Now using the .done_probing() callback for AUX bus to prevent
>    probe deferral loops in case the panel-edp driver is a module
>    as previously seen with another bridge driver (ANX7625) on
>    some other SoCs (MT8192 and others)
>  - Rebased over next-20230706
>  - Dropped Chen-Yu's T-b tag on last patch as some logic changed
>    (before, I wasn't using the .done_probing() callback).
>
> Changes in v3:
>  - Added DPTX AUX block initialization before trying to communicate
>    to stop relying on the bootloader keeping it initialized before
>    booting Linux.
>  - Fixed commit description for patch [09/09] and removed commented
>    out code (that slipped from dev phase.. sorry!).
>
> This series adds "real" support for eDP in the mtk-dp DisplayPort driver.
>
> Explaining the "real":
> Before this change, the DisplayPort driver did support eDP to some
> extent, but it was treating it entirely like a regular DP interface
> which is partially fine, after all, embedded DisplayPort *is* actually
> DisplayPort, but there might be some differences to account for... and
> this is for both small performance improvements and, more importantly,
> for correct functionality in some systems.
>
> Functionality first:
>
> One of the common differences found in various boards implementing eDP
> and machines using an eDP panel is that many times the HPD line is not
> connected. This *must* be accounted for: at startup, this specific IP
> will raise a HPD interrupt (which should maybe be ignored... as it does
> not appear to be a "real" event...) that will make the eDP panel to be
> detected and to actually work but, after a suspend-resume cycle, there
> will be no HPD interrupt (as there's no HPD line in my case!) producing
> a functionality issue - specifically, the DP Link Training fails because
> the panel doesn't get powered up, then it stays black and won't work
> until rebooting the machine (or removing and reinserting the module I
> think, but I haven't tried that).
>
> Now for.. both:
> eDP panels are *e*DP because they are *not* removable (in the sense that
> you can't unplug the cable without disassembling the machine, in which
> case, the machine shall be powered down..!): this (correct) assumption
> makes us able to solve some issues and to also gain a little performance
> during PM operations.
>
> What was done here is:
>  - Caching the EDID if the panel is eDP: we're always going to read the
>    same data everytime, so we can just cache that (as it's small enough)
>    shortening PM resume times for the eDP driver instance;
>  - Always return connector_status_connected if it's eDP: non-removable
>    means connector_status_disconnected can't happen during runtime...
>    this also saves us some time and even power, as we won't have to
>    perform yet another power cycle of the HW;
>  - Added aux-bus support!
>    This makes us able to rely on panel autodetection from the EDID,
>    avoiding to add more and more panel timings to panel-edp and, even
>    better, allowing to use one panel node in devicetrees for multiple
>    variants of the same machine since, at that point, it's not important
>    to "preventively know" what panel we have (eh, it's autodetected...!).
>
> This was tested on a MT8195 Cherry Tomato Chromebook (panel-edp on aux-bus)
>
>
> P.S.: For your own testing commodity, here's a reference devicetree:
>
> pp3300_disp_x: regulator-pp3300-disp-x {
>         compatible = "regulator-fixed";
>         regulator-name = "pp3300_disp_x";
>         regulator-min-microvolt = <3300000>;
>         regulator-max-microvolt = <3300000>;
>         enable-active-high;
>         gpio = <&pio 55 GPIO_ACTIVE_HIGH>;
>         pinctrl-names = "default";
>         pinctrl-0 = <&panel_fixed_pins>;
> };
>
> &edp_tx {
>         status = "okay";
>
>         pinctrl-names = "default";
>         pinctrl-0 = <&edptx_pins_default>;
>
>         ports {
>                 #address-cells = <1>;
>                 #size-cells = <0>;
>
>                 port@0 {
>                         reg = <0>;
>                         edp_in: endpoint {
>                                 remote-endpoint = <&dp_intf0_out>;
>                         };
>                 };
>
>                 port@1 {
>                         reg = <1>;
>                         edp_out: endpoint {
>                                 data-lanes = <0 1 2 3>;
>                                 remote-endpoint = <&panel_in>;
>                         };
>                 };
>         };
>
>         aux-bus {
>                 panel: panel {
>                         compatible = "edp-panel";
>                         power-supply = <&pp3300_disp_x>;
>                         backlight = <&backlight_lcd0>;
>                         port {
>                                 panel_in: endpoint {
>                                         remote-endpoint = <&edp_out>;
>                                 };
>                         };
>                 };
>         };
> };
>
> AngeloGioacchino Del Regno (11):
>   drm/mediatek: dp: Add missing error checks in
>     mtk_dp_parse_capabilities
>   drm/mediatek: dp: Move AUX and panel poweron/off sequence to function
>   drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer()
>   drm/mediatek: dp: Use devm variant of drm_bridge_add()
>   drm/mediatek: dp: Move AUX_P0 setting to
>     mtk_dp_initialize_aux_settings()
>   drm/mediatek: dp: Enable event interrupt only when bridge attached
>   drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled
>   drm/mediatek: dp: Move PHY registration to new function
>   drm/mediatek: dp: Add support for embedded DisplayPort aux-bus
>   drm/mediatek: dp: Add .wait_hpd_asserted() for AUX bus
>   drm/mediatek: dp: Don't register HPD interrupt handler for eDP case
>
>  drivers/gpu/drm/mediatek/Kconfig  |   1 +
>  drivers/gpu/drm/mediatek/mtk_dp.c | 360 ++++++++++++++++++++----------
>  2 files changed, 242 insertions(+), 119 deletions(-)
>
> --
> 2.40.1
>

Re: [PATCH v6 05/11] drm/mediatek: dp: Move AUX_P0 setting to mtk_dp_initialize_aux_settings()

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Move the register write to MTK_DP_AUX_P0_3690 to set the AUX reply
> mode
> to function mtk_dp_initialize_aux_settings(), as this is effectively
> part of the DPTX AUX setup sequence.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> Tested-by: Chen-Yu Tsai <wenst@chromium.org>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index fc6cabf5370b..e8d3bf310608 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1009,6 +1009,11 @@ static void
> mtk_dp_initialize_aux_settings(struct mtk_dp *mtk_dp)
>  	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_37C8,
>  			   MTK_ATOP_EN_AUX_TX_P0,
>  			   MTK_ATOP_EN_AUX_TX_P0);
> +
> +	/* Set complete reply mode for AUX */
> +	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_3690,
> +			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0,
> +			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0);
>  }
>  
>  static void mtk_dp_initialize_digital_settings(struct mtk_dp
> *mtk_dp)
> @@ -1826,10 +1831,6 @@ static void mtk_dp_init_port(struct mtk_dp
> *mtk_dp)
>  	mtk_dp_initialize_settings(mtk_dp);
>  	mtk_dp_initialize_aux_settings(mtk_dp);
>  	mtk_dp_initialize_digital_settings(mtk_dp);
> -
> -	mtk_dp_update_bits(mtk_dp, MTK_DP_AUX_P0_3690,
> -			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0,
> -			   RX_REPLY_COMPLETE_MODE_AUX_TX_P0);
>  	mtk_dp_initialize_hpd_detect_settings(mtk_dp);
>  
>  	mtk_dp_digital_sw_reset(mtk_dp);
> -- 
> 2.40.1

Re: [PATCH v6 06/11] drm/mediatek: dp: Enable event interrupt only when bridge attached

[Alexandre Mergnat]

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> It is useless and error-prone to enable the DisplayPort event interrupt
> before finishing to probe and install the driver, as the DP training
> cannot happen before the entire pipeline is correctly set up, as the
> interrupt handler also requires the full hardware to be initialized by
> mtk_dp_bridge_attach().
> 
> Anyway, depending in which state the controller is left from the
> bootloader, this may cause an interrupt storm and consequently hang
> the kernel during boot, so, avoid enabling the interrupt until we
> reach a clean state by adding the IRQ_NOAUTOEN flag before requesting
> it at probe time and manage the enablement of the ISR in the .attach()
> and .detach() handlers for the DP bridge.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

-- 
Regards,
Alexandre

Re: [PATCH v6 07/11] drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled

[Alexandre Mergnat]

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> If a controller (usually, eDP!) does not support audio, or audio is not
> enabled because the endpoint has no audio support, it's useless to lock
> a mutex only to unlock it right after because there's no .plugged_cb().
> 
> Check if the audio is supported and enabled before locking the mutex in
> mtk_dp_update_plugged_status(): if not, we simply return immediately.
> 
> While at it, since the update_plugged_status_lock mutex would not be
> used if the controller doesn't support audio at all, initialize it
> only if `audio_supported` is true.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

-- 
Regards,
Alexandre

Re: [PATCH v6 08/11] drm/mediatek: dp: Move PHY registration to new function

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> In preparation for adding support for eDP, move the PHY registration
> code to a new mtk_dp_register_phy() function for better readability.
> 
> This commit brings no functional changes.

-- 
Regards,
Alexandre

Re: [PATCH v6 09/11] drm/mediatek: dp: Add support for embedded DisplayPort aux-bus

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> For the eDP case we can support using aux-bus on MediaTek DP: this
> gives us the possibility to declare our panel as generic "panel-edp"
> which will automatically configure the timings and available modes
> via the EDID that we read from it.
> 
> To do this, move the panel parsing at the end of the probe function
> so that the hardware is initialized beforehand and also initialize
> the DPTX AUX block and power both on as, when we populate the
> aux-bus, the panel driver will trigger an EDID read to perform
> panel detection.
> 
> Last but not least, since now the AUX transfers can happen in the
> separated aux-bus, it was necessary to add an exclusion for the
> cable_plugged_in check in `mtk_dp_aux_transfer()` and the easiest
> way to do this is to simply ignore checking that when the bridge
> type is eDP.

-- 
Regards,
Alexandre

Re: [PATCH v6 10/11] drm/mediatek: dp: Add .wait_hpd_asserted() for AUX bus

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> In order to support usecases in which the panel regulator can be
> switched on and off to save power, and usecases in which the panel
> regulator is off at boot, add a .wait_hpd_asserted() callback for
> the AUX bus: this will make sure to wait until the panel is fully
> ready after power-on before trying to communicate with it.
> 
> Also, parse the eDP display capabilities in that callback, so that
> we can also avoid using the .get_edid() callback from this bridge.
> 
> Since at this point the hpd machinery is performed in the new hpd
> callback and the detection and edid reading are done outside of
> this driver, assign the DRM_BRIDGE_OP_{DETECT, EDID, HPD} ops and
> register the bridge unconditionally at probe time only if we are
> probing full DisplayPort and not eDP while, for the latter, we
> register the bridge in the .done_probing() callback and only if
> the panel was found and triggered HPD.

-- 
Regards,
Alexandre

Re: [PATCH v6 11/11] drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> The interrupt handler for HPD is useful only if a display is actually
> supposed to be hotpluggable, as that manages the machinery to perform
> cable (un)plug detection, debouncing and setup for re-training.
> 
> Since eDP panels are not supposed to be hotpluggable we can avoid
> using the HPD interrupts altogether and rely on HPD polling only
> for the suspend/resume case, saving us some spinlocking action and
> the overhead of interrupts firing at every suspend/resume cycle,
> achieving a faster (even if just slightly) display resume.

-- 
Regards,
Alexandre

Re: [PATCH v6 01/11] drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> If reading the RX capabilities fails the training pattern will be set
> wrongly: add error checking for drm_dp_read_dpcd_caps() and return if
> anything went wrong with it.
> 
> While at it, also add a less critical error check when writing to
> clear the ESI0 IRQ vector.

-- 
Regards,
Alexandre

Re: [PATCH v6 02/11] drm/mediatek: dp: Move AUX and panel poweron/off sequence to function

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> Everytime we run bridge detection and/or EDID read we run a poweron
> and poweroff sequence for both the AUX and the panel; moreover, this
> is also done when enabling the bridge in the .atomic_enable() callback.
> 
> Move this power on/off sequence to a new mtk_dp_aux_panel_poweron()
> function as to commonize it.
> Note that, before this commit, in mtk_dp_bridge_atomic_enable() only
> the AUX was getting powered on but the panel was left powered off if
> the DP cable wasn't plugged in while now we unconditionally send a D0
> request and this is done for two reasons:
>   - First, whether this request fails or not, it takes the same time
>     and anyway the DP hardware won't produce any error (or, if it
>     does, it's ignorable because it won't block further commands)
>   - Second, training the link between a sleeping/standby/unpowered
>     display makes little sense.

-- 
Regards,
Alexandre

Re: [PATCH v6 03/11] drm/mediatek: dp: Change logging to dev for mtk_dp_aux_transfer()

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> Change logging from drm_{err,info}() to dev_{err,info}() in functions
> mtk_dp_aux_transfer() and mtk_dp_aux_do_transfer(): this will be
> essential to avoid getting NULL pointer kernel panics if any kind
> of error happens during AUX transfers happening before the bridge
> is attached.
> 
> This may potentially start happening in a later commit implementing
> aux-bus support, as AUX transfers will be triggered from the panel
> driver (for EDID) before the mtk-dp bridge gets attached, and it's
> done in preparation for the same.

-- 
Regards,
Alexandre

Re: [PATCH v6 04/11] drm/mediatek: dp: Use devm variant of drm_bridge_add()

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> In preparation for adding support for aux-bus, which will add a code
> path that may fail after the drm_bridge_add() call, change that to
> devm_drm_bridge_add() to simplify failure paths later.

-- 
Regards,
Alexandre

Re: [PATCH v6 05/11] drm/mediatek: dp: Move AUX_P0 setting to mtk_dp_initialize_aux_settings()

[Alexandre Mergnat]

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> Move the register write to MTK_DP_AUX_P0_3690 to set the AUX reply mode
> to function mtk_dp_initialize_aux_settings(), as this is effectively
> part of the DPTX AUX setup sequence.

-- 
Regards,
Alexandre

Re: [PATCH v6 07/11] drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  If a controller (usually, eDP!) does not support audio, or audio is
> not
> enabled because the endpoint has no audio support, it's useless to
> lock
> a mutex only to unlock it right after because there's no
> .plugged_cb().
> 
> Check if the audio is supported and enabled before locking the mutex
> in
> mtk_dp_update_plugged_status(): if not, we simply return immediately.
> 
> While at it, since the update_plugged_status_lock mutex would not be
> used if the controller doesn't support audio at all, initialize it
> only if `audio_supported` is true.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 83e55f8dc84a..c1d1a882f1db 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1948,6 +1948,9 @@ static int mtk_dp_dt_parse(struct mtk_dp
> *mtk_dp,
>  
>  static void mtk_dp_update_plugged_status(struct mtk_dp *mtk_dp)
>  {
> +	if (!mtk_dp->data->audio_supported || !mtk_dp->audio_enable)
> +		return;
> +
>  	mutex_lock(&mtk_dp->update_plugged_status_lock);
>  	if (mtk_dp->plugged_cb && mtk_dp->codec_dev)
>  		mtk_dp->plugged_cb(mtk_dp->codec_dev,
> @@ -2520,11 +2523,11 @@ static int mtk_dp_probe(struct
> platform_device *pdev)
>  		return dev_err_probe(dev, ret,
>  				     "failed to request mediatek dptx
> irq\n");
>  
> -	mutex_init(&mtk_dp->update_plugged_status_lock);
> -
>  	platform_set_drvdata(pdev, mtk_dp);
>  
>  	if (mtk_dp->data->audio_supported) {
> +		mutex_init(&mtk_dp->update_plugged_status_lock);
> +
>  		ret = mtk_dp_register_audio_driver(dev);
>  		if (ret) {
>  			dev_err(dev, "Failed to register audio driver:
> %d\n",
> -- 
> 2.40.1

Re: [PATCH v6 09/11] drm/mediatek: dp: Add support for embedded DisplayPort aux-bus

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  For the eDP case we can support using aux-bus on MediaTek DP: this
> gives us the possibility to declare our panel as generic "panel-edp"
> which will automatically configure the timings and available modes
> via the EDID that we read from it.
> 
> To do this, move the panel parsing at the end of the probe function
> so that the hardware is initialized beforehand and also initialize
> the DPTX AUX block and power both on as, when we populate the
> aux-bus, the panel driver will trigger an EDID read to perform
> panel detection.
> 
> Last but not least, since now the AUX transfers can happen in the
> separated aux-bus, it was necessary to add an exclusion for the
> cable_plugged_in check in `mtk_dp_aux_transfer()` and the easiest
> way to do this is to simply ignore checking that when the bridge
> type is eDP.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/Kconfig  |  1 +
>  drivers/gpu/drm/mediatek/mtk_dp.c | 84 ++++++++++++++++++++++++++++-
> --
>  2 files changed, 79 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/Kconfig
> b/drivers/gpu/drm/mediatek/Kconfig
> index b451dee64d34..76cab28e010c 100644
> --- a/drivers/gpu/drm/mediatek/Kconfig
> +++ b/drivers/gpu/drm/mediatek/Kconfig
> @@ -26,6 +26,7 @@ config DRM_MEDIATEK_DP
>  	select PHY_MTK_DP
>  	select DRM_DISPLAY_HELPER
>  	select DRM_DISPLAY_DP_HELPER
> +	select DRM_DP_AUX_BUS
>  	help
>  	  DRM/KMS Display Port driver for MediaTek SoCs.
>  
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 1b4219e6a00b..acdd457b5449 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -4,6 +4,7 @@
>   * Copyright (c) 2022 BayLibre
>   */
>  
> +#include <drm/display/drm_dp_aux_bus.h>
>  #include <drm/display/drm_dp.h>
>  #include <drm/display/drm_dp_helper.h>
>  #include <drm/drm_atomic_helper.h>
> @@ -1313,9 +1314,11 @@ static void mtk_dp_power_disable(struct mtk_dp
> *mtk_dp)
>  
>  static void mtk_dp_initialize_priv_data(struct mtk_dp *mtk_dp)
>  {
> +	bool plugged_in = (mtk_dp->bridge.type ==
> DRM_MODE_CONNECTOR_eDP);
> +
>  	mtk_dp->train_info.link_rate = DP_LINK_BW_5_4;
>  	mtk_dp->train_info.lane_count = mtk_dp->max_lanes;
> -	mtk_dp->train_info.cable_plugged_in = false;
> +	mtk_dp->train_info.cable_plugged_in = plugged_in;
>  
>  	mtk_dp->info.format = DP_PIXELFORMAT_RGB;
>  	memset(&mtk_dp->info.vm, 0, sizeof(struct videomode));
> @@ -1617,6 +1620,16 @@ static int mtk_dp_parse_capabilities(struct
> mtk_dp *mtk_dp)
>  	u8 val;
>  	ssize_t ret;
>  
> +	/*
> +	 * If we're eDP and capabilities were already parsed we can
> skip
> +	 * reading again because eDP panels aren't hotpluggable hence
> the
> +	 * caps and training information won't ever change in a boot
> life
> +	 */
> +	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP &&
> +	    mtk_dp->rx_cap[DP_MAX_LINK_RATE] &&
> +	    mtk_dp->train_info.sink_ssc)
> +		return 0;
> +
>  	ret = drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
>  	if (ret < 0)
>  		return ret;
> @@ -2030,15 +2043,14 @@ static struct edid *mtk_dp_get_edid(struct
> drm_bridge *bridge,
>  static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
>  				   struct drm_dp_aux_msg *msg)
>  {
> -	struct mtk_dp *mtk_dp;
> +	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp,
> aux);
>  	bool is_read;
>  	u8 request;
>  	size_t accessed_bytes = 0;
>  	int ret;
>  
> -	mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
> -
> -	if (!mtk_dp->train_info.cable_plugged_in) {
> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP &&
> +	    !mtk_dp->train_info.cable_plugged_in) {
>  		ret = -EAGAIN;
>  		goto err;
>  	}
> @@ -2501,6 +2513,28 @@ static int mtk_dp_register_phy(struct mtk_dp
> *mtk_dp)
>  	return 0;
>  }
>  
> +static int mtk_dp_edp_link_panel(struct drm_dp_aux *mtk_aux)
> +{
> +	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp,
> aux);
> +	struct device *dev = mtk_aux->dev;
> +	int ret;
> +
> +	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 
> 1, 0);
> +
> +	/* Power off the DP and AUX: either detection is done, or no
> panel present */
> +	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +			   DP_PWR_STATE_BANDGAP_TPLL,
> +			   DP_PWR_STATE_MASK);
> +	mtk_dp_power_disable(mtk_dp);
> +
> +	if (IS_ERR(mtk_dp->next_bridge)) {
> +		ret = PTR_ERR(mtk_dp->next_bridge);
> +		mtk_dp->next_bridge = NULL;
> +		return ret;
> +	}
> +	return 0;
> +}
> +
>  static int mtk_dp_probe(struct platform_device *pdev)
>  {
>  	struct mtk_dp *mtk_dp;
> @@ -2531,9 +2565,10 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  	if (ret)
>  		return dev_err_probe(dev, ret, "Failed to parse dt\n");
>  
> -	drm_dp_aux_init(&mtk_dp->aux);
>  	mtk_dp->aux.name = "aux_mtk_dp";
> +	mtk_dp->aux.dev = dev;
>  	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
> +	drm_dp_aux_init(&mtk_dp->aux);
>  
>  	spin_lock_init(&mtk_dp->irq_thread_lock);
>  
> @@ -2577,6 +2612,43 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  	mtk_dp->need_debounce = true;
>  	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
>  
> +	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
> +		/*
> +		 * Set the data lanes to idle in case the bootloader
> didn't
> +		 * properly close the eDP port to avoid stalls and then
> +		 * reinitialize, reset and power on the AUX block.
> +		 */
> +		mtk_dp_set_idle_pattern(mtk_dp, true);
> +		mtk_dp_initialize_aux_settings(mtk_dp);
> +		mtk_dp_power_enable(mtk_dp);
> +
> +		/*
> +		 * Power on the AUX to allow reading the EDID from aux-
> bus:
> +		 * please note that it is necessary to call power off
> in the
> +		 * .done_probing() callback (mtk_dp_edp_link_panel), as
> only
> +		 * there we can safely assume that we finished reading
> EDID.
> +		 */
> +		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> +				   DP_PWR_STATE_MASK);
> +
> +		ret = devm_of_dp_aux_populate_bus(&mtk_dp->aux,
> mtk_dp_edp_link_panel);
> +		if (ret) {
> +			/* -ENODEV this means that the panel is not on
> the aux-bus */
> +			if (ret == -ENODEV) {
> +				ret = mtk_dp_edp_link_panel(&mtk_dp-
> >aux);
> +				if (ret)
> +					return ret;
> +			} else {
> +				mtk_dp_update_bits(mtk_dp,
> MTK_DP_TOP_PWR_STATE,
> +						   DP_PWR_STATE_BANDGAP
> _TPLL,
> +						   DP_PWR_STATE_MASK);
> +				mtk_dp_power_disable(mtk_dp);
> +				return ret;
> +			}
> +		}
> +	}
> +
>  	pm_runtime_enable(dev);
>  	pm_runtime_get_sync(dev);
>  
> -- 
> 2.40.1

Re: [PATCH v6 10/11] drm/mediatek: dp: Add .wait_hpd_asserted() for AUX bus

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  In order to support usecases in which the panel regulator can be
> switched on and off to save power, and usecases in which the panel
> regulator is off at boot, add a .wait_hpd_asserted() callback for
> the AUX bus: this will make sure to wait until the panel is fully
> ready after power-on before trying to communicate with it.
> 
> Also, parse the eDP display capabilities in that callback, so that
> we can also avoid using the .get_edid() callback from this bridge.
> 
> Since at this point the hpd machinery is performed in the new hpd
> callback and the detection and edid reading are done outside of
> this driver, assign the DRM_BRIDGE_OP_{DETECT, EDID, HPD} ops and
> register the bridge unconditionally at probe time only if we are
> probing full DisplayPort and not eDP while, for the latter, we
> register the bridge in the .done_probing() callback and only if
> the panel was found and triggered HPD.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 45 ++++++++++++++++++++++++++---
> --
>  1 file changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index acdd457b5449..e74295ba9707 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1920,6 +1920,31 @@ static irqreturn_t mtk_dp_hpd_event(int hpd,
> void *dev)
>  	return IRQ_WAKE_THREAD;
>  }
>  
> +static int mtk_dp_wait_hpd_asserted(struct drm_dp_aux *mtk_aux,
> unsigned long wait_us)
> +{
> +	struct mtk_dp *mtk_dp = container_of(mtk_aux, struct mtk_dp,
> aux);
> +	u32 val;
> +	int ret;
> +
> +	ret = regmap_read_poll_timeout(mtk_dp->regs,
> MTK_DP_TRANS_P0_3414,
> +				       val, !!(val &
> HPD_DB_DP_TRANS_P0_MASK),
> +				       wait_us / 100, wait_us);
> +	if (ret) {
> +		mtk_dp->train_info.cable_plugged_in = false;
> +		return ret;
> +	}
> +
> +	mtk_dp->train_info.cable_plugged_in = true;
> +
> +	ret = mtk_dp_parse_capabilities(mtk_dp);
> +	if (ret) {
> +		drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
>  			   struct platform_device *pdev)
>  {
> @@ -2532,6 +2557,12 @@ static int mtk_dp_edp_link_panel(struct
> drm_dp_aux *mtk_aux)
>  		mtk_dp->next_bridge = NULL;
>  		return ret;
>  	}
> +
> +	/* For eDP, we add the bridge only if the panel was found */
> +	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
>  
> @@ -2568,6 +2599,7 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  	mtk_dp->aux.name = "aux_mtk_dp";
>  	mtk_dp->aux.dev = dev;
>  	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
> +	mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
>  	drm_dp_aux_init(&mtk_dp->aux);
>  
>  	spin_lock_init(&mtk_dp->irq_thread_lock);
> @@ -2600,15 +2632,8 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  
>  	mtk_dp->bridge.funcs = &mtk_dp_bridge_funcs;
>  	mtk_dp->bridge.of_node = dev->of_node;
> -
> -	mtk_dp->bridge.ops =
> -		DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
> DRM_BRIDGE_OP_HPD;
>  	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
>  
> -	ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
> -	if (ret)
> -		return dev_err_probe(dev, ret, "Failed to add
> bridge\n");
> -
>  	mtk_dp->need_debounce = true;
>  	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
>  
> @@ -2647,6 +2672,12 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  				return ret;
>  			}
>  		}
> +	} else {
> +		mtk_dp->bridge.ops = DRM_BRIDGE_OP_DETECT |
> +				     DRM_BRIDGE_OP_EDID |
> DRM_BRIDGE_OP_HPD;
> +		ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
> +		if (ret)
> +			return dev_err_probe(dev, ret, "Failed to add
> bridge\n");
>  	}
>  
>  	pm_runtime_enable(dev);
> -- 
> 2.40.1

Re: [PATCH v6 11/11] drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

[CK Hu (胡俊光)]

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Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  The interrupt handler for HPD is useful only if a display is
> actually
> supposed to be hotpluggable, as that manages the machinery to perform
> cable (un)plug detection, debouncing and setup for re-training.
> 
> Since eDP panels are not supposed to be hotpluggable we can avoid
> using the HPD interrupts altogether and rely on HPD polling only
> for the suspend/resume case, saving us some spinlocking action and
> the overhead of interrupts firing at every suspend/resume cycle,
> achieving a faster (even if just slightly) display resume.
> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 81 ++++++++++++++++++-----------
> --
>  1 file changed, 46 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index e74295ba9707..c06fcc7318e7 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -2182,9 +2182,11 @@ static int mtk_dp_bridge_attach(struct
> drm_bridge *bridge,
>  
>  	mtk_dp->drm_dev = bridge->dev;
>  
> -	irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> -	enable_irq(mtk_dp->irq);
> -	mtk_dp_hwirq_enable(mtk_dp, true);
> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> +		irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> +		enable_irq(mtk_dp->irq);
> +		mtk_dp_hwirq_enable(mtk_dp, true);
> +	}
>  
>  	return 0;
>  
> @@ -2199,8 +2201,10 @@ static void mtk_dp_bridge_detach(struct
> drm_bridge *bridge)
>  {
>  	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
>  
> -	mtk_dp_hwirq_enable(mtk_dp, false);
> -	disable_irq(mtk_dp->irq);
> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
> +		mtk_dp_hwirq_enable(mtk_dp, false);
> +		disable_irq(mtk_dp->irq);
> +	}
>  	mtk_dp->drm_dev = NULL;
>  	mtk_dp_poweroff(mtk_dp);
>  	drm_dp_aux_unregister(&mtk_dp->aux);
> @@ -2579,40 +2583,44 @@ static int mtk_dp_probe(struct
> platform_device *pdev)
>  	mtk_dp->dev = dev;
>  	mtk_dp->data = (struct mtk_dp_data
> *)of_device_get_match_data(dev);
>  
> -	mtk_dp->irq = platform_get_irq(pdev, 0);
> -	if (mtk_dp->irq < 0)
> -		return dev_err_probe(dev, mtk_dp->irq,
> -				     "failed to request dp irq
> resource\n");
> -
> -	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 
> 1, 0);
> -	if (IS_ERR(mtk_dp->next_bridge) &&
> -	    PTR_ERR(mtk_dp->next_bridge) == -ENODEV)
> -		mtk_dp->next_bridge = NULL;
> -	else if (IS_ERR(mtk_dp->next_bridge))
> -		return dev_err_probe(dev, PTR_ERR(mtk_dp->next_bridge),
> -				     "Failed to get bridge\n");
> -

Why remove next_bridge setting?

Regards,
CK

>  	ret = mtk_dp_dt_parse(mtk_dp, pdev);
>  	if (ret)
>  		return dev_err_probe(dev, ret, "Failed to parse dt\n");
>  
> +	/*
> +	 * Request the interrupt and install service routine only if we
> are
> +	 * on full DisplayPort.
> +	 * For eDP, polling the HPD instead is more convenient because
> we
> +	 * don't expect any (un)plug events during runtime, hence we
> can
> +	 * avoid some locking.
> +	 */
> +	if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP) {
> +		mtk_dp->irq = platform_get_irq(pdev, 0);
> +		if (mtk_dp->irq < 0)
> +			return dev_err_probe(dev, mtk_dp->irq,
> +					     "failed to request dp irq
> resource\n");
> +
> +		spin_lock_init(&mtk_dp->irq_thread_lock);
> +
> +		irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> +		ret = devm_request_threaded_irq(dev, mtk_dp->irq,
> mtk_dp_hpd_event,
> +						mtk_dp_hpd_event_thread
> ,
> +						IRQ_TYPE_LEVEL_HIGH,
> dev_name(dev),
> +						mtk_dp);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "failed to request
> mediatek dptx irq\n");
> +
> +		mtk_dp->need_debounce = true;
> +		timer_setup(&mtk_dp->debounce_timer,
> mtk_dp_debounce_timer, 0);
> +	}
> +
>  	mtk_dp->aux.name = "aux_mtk_dp";
>  	mtk_dp->aux.dev = dev;
>  	mtk_dp->aux.transfer = mtk_dp_aux_transfer;
>  	mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
>  	drm_dp_aux_init(&mtk_dp->aux);
>  
> -	spin_lock_init(&mtk_dp->irq_thread_lock);
> -
> -	irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
> -	ret = devm_request_threaded_irq(dev, mtk_dp->irq,
> mtk_dp_hpd_event,
> -					mtk_dp_hpd_event_thread,
> -					IRQ_TYPE_LEVEL_HIGH,
> dev_name(dev),
> -					mtk_dp);
> -	if (ret)
> -		return dev_err_probe(dev, ret,
> -				     "failed to request mediatek dptx
> irq\n");
> -
>  	platform_set_drvdata(pdev, mtk_dp);
>  
>  	if (mtk_dp->data->audio_supported) {
> @@ -2634,9 +2642,6 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  	mtk_dp->bridge.of_node = dev->of_node;
>  	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
>  
> -	mtk_dp->need_debounce = true;
> -	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
> -
>  	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
>  		/*
>  		 * Set the data lanes to idle in case the bootloader
> didn't
> @@ -2647,6 +2652,9 @@ static int mtk_dp_probe(struct platform_device
> *pdev)
>  		mtk_dp_initialize_aux_settings(mtk_dp);
>  		mtk_dp_power_enable(mtk_dp);
>  
> +		/* Disable HW interrupts: we don't need any for eDP */
> +		mtk_dp_hwirq_enable(mtk_dp, false);
> +
>  		/*
>  		 * Power on the AUX to allow reading the EDID from aux-
> bus:
>  		 * please note that it is necessary to call power off
> in the
> @@ -2692,7 +2700,8 @@ static int mtk_dp_remove(struct platform_device
> *pdev)
>  
>  	pm_runtime_put(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> -	del_timer_sync(&mtk_dp->debounce_timer);
> +	if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP)
> +		del_timer_sync(&mtk_dp->debounce_timer);
>  	platform_device_unregister(mtk_dp->phy_dev);
>  	if (mtk_dp->audio_pdev)
>  		platform_device_unregister(mtk_dp->audio_pdev);
> @@ -2706,7 +2715,8 @@ static int mtk_dp_suspend(struct device *dev)
>  	struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
>  
>  	mtk_dp_power_disable(mtk_dp);
> -	mtk_dp_hwirq_enable(mtk_dp, false);
> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> +		mtk_dp_hwirq_enable(mtk_dp, false);
>  	pm_runtime_put_sync(dev);
>  
>  	return 0;
> @@ -2718,7 +2728,8 @@ static int mtk_dp_resume(struct device *dev)
>  
>  	pm_runtime_get_sync(dev);
>  	mtk_dp_init_port(mtk_dp);
> -	mtk_dp_hwirq_enable(mtk_dp, true);
> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
> +		mtk_dp_hwirq_enable(mtk_dp, true);
>  	mtk_dp_power_enable(mtk_dp);
>  
>  	return 0;
> -- 
> 2.40.1

Re: [PATCH v6 11/11] drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

[AngeloGioacchino Del Regno]

Il 25/07/23 08:37, CK Hu (胡俊光) ha scritto:
> Hi, Angelo:
> 
> On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>>   	
>> External email : Please do not click links or open attachments until
>> you have verified the sender or the content.
>>   The interrupt handler for HPD is useful only if a display is
>> actually
>> supposed to be hotpluggable, as that manages the machinery to perform
>> cable (un)plug detection, debouncing and setup for re-training.
>>
>> Since eDP panels are not supposed to be hotpluggable we can avoid
>> using the HPD interrupts altogether and rely on HPD polling only
>> for the suspend/resume case, saving us some spinlocking action and
>> the overhead of interrupts firing at every suspend/resume cycle,
>> achieving a faster (even if just slightly) display resume.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <
>> angelogioacchino.delregno@collabora.com>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dp.c | 81 ++++++++++++++++++-----------
>> --
>>   1 file changed, 46 insertions(+), 35 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
>> b/drivers/gpu/drm/mediatek/mtk_dp.c
>> index e74295ba9707..c06fcc7318e7 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
>> @@ -2182,9 +2182,11 @@ static int mtk_dp_bridge_attach(struct
>> drm_bridge *bridge,
>>   
>>   	mtk_dp->drm_dev = bridge->dev;
>>   
>> -	irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
>> -	enable_irq(mtk_dp->irq);
>> -	mtk_dp_hwirq_enable(mtk_dp, true);
>> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
>> +		irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
>> +		enable_irq(mtk_dp->irq);
>> +		mtk_dp_hwirq_enable(mtk_dp, true);
>> +	}
>>   
>>   	return 0;
>>   
>> @@ -2199,8 +2201,10 @@ static void mtk_dp_bridge_detach(struct
>> drm_bridge *bridge)
>>   {
>>   	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
>>   
>> -	mtk_dp_hwirq_enable(mtk_dp, false);
>> -	disable_irq(mtk_dp->irq);
>> +	if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
>> +		mtk_dp_hwirq_enable(mtk_dp, false);
>> +		disable_irq(mtk_dp->irq);
>> +	}
>>   	mtk_dp->drm_dev = NULL;
>>   	mtk_dp_poweroff(mtk_dp);
>>   	drm_dp_aux_unregister(&mtk_dp->aux);
>> @@ -2579,40 +2583,44 @@ static int mtk_dp_probe(struct
>> platform_device *pdev)
>>   	mtk_dp->dev = dev;
>>   	mtk_dp->data = (struct mtk_dp_data
>> *)of_device_get_match_data(dev);
>>   
>> -	mtk_dp->irq = platform_get_irq(pdev, 0);
>> -	if (mtk_dp->irq < 0)
>> -		return dev_err_probe(dev, mtk_dp->irq,
>> -				     "failed to request dp irq
>> resource\n");
>> -
>> -	mtk_dp->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node,
>> 1, 0);
>> -	if (IS_ERR(mtk_dp->next_bridge) &&
>> -	    PTR_ERR(mtk_dp->next_bridge) == -ENODEV)
>> -		mtk_dp->next_bridge = NULL;
>> -	else if (IS_ERR(mtk_dp->next_bridge))
>> -		return dev_err_probe(dev, PTR_ERR(mtk_dp->next_bridge),
>> -				     "Failed to get bridge\n");
>> -
> 
> Why remove next_bridge setting?
> 

Hello CK,

Thanks for making me notice that! The removal of this code snippet belongs
to patch [9/11] `drm/mediatek: dp: Add support for embedded DisplayPort aux-bus`
because in that patch I am moving the call to devm_drm_of_get_bridge() to function
mtk_dp_edp_link_panel(), which is called as a .done_probing() callback if the eDP
panel is on aux-bus, or "manually" if not on aux-bus.

I'll send a v7 with the removal of this snippet in the right patch.

Thanks again,
Angelo