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* [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect
@ 2020-04-21  5:06 Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Douglas Anderson
                   ` (5 more replies)
  0 siblings, 6 replies; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, Andy Gross, Krzysztof Kozlowski, Paul Walmsley,
	Sam Ravnborg, Stephen Boyd, Thierry Reding, linux-kernel


As talked about in commit c2bfc223882d ("drm/bridge: ti-sn65dsi86:
Remove the mystery delay"), the normal HPD pin on ti-sn65dsi86 is
kinda useless, at least for embedded DisplayPort (eDP).  However,
despite the fact that the actual HPD pin on the bridge is mostly
useless for eDP, the concept of HPD for eDP still makes sense.  It
allows us to optimize out a hardcoded delay that many panels need if
HPD isn't hooked up.  Panel timing diagrams show HPD as one of the
events to measure timing from and we have to assume the worst case if
we can't actually read HPD.

One way to use HPD for eDP without using the mostly useless HPD pin on
ti-sn65dsi86 is to route the panel's HPD somewhere else in the system,
like to a GPIO.  This works great because eDP panels aren't physically
hotplugged.  That means the debouncing logic that caused us problems
wasn't really needed and a raw GPIO works great.

As per the above, a smart board designer would realize the value of
HPD and choose to route it to a GPIO somewhere on the board to avoid
the silly sn65dsi86 debouncing.  While said "smart designer" could
theoretically route HPD anywhere on the board, a really smart designer
would realize that there are several GPIOs on the bridge itself that
are nearly useless for anything but this purpose and route HPD to one
of those.

This series of patches is intended to allow the scenario described
above.

This patch has been tested on a board that is not yet mainline.  On
the hardware I have:
- Panel spec says HPD could take up to 200 ms to come up, so without
  HPD hooked up we need to delay 200 ms.
- On my board the panel is powered by the same rail as the
  touchscreen.  By chance of probe order the touchscreen comes up
  first.  This means by the time we check HPD in ti_sn_bridge_enable()
  it's already up.  Thus we can use the panel on 200 ms earlier.
- If I measure HPD on this pane it comes up ~56 ms after the panel is
  powered.  This means I can save 144 ms of delay.

Side effects (though not main goals) of this series are:
- ti-sn65dsi86 GPIOs are now exported in Linux.
- ti-sn65dsi86 bindings are converted to yaml.
- Common panel bindings now have "hpd-gpios" listed.
- The simple-panel driver in Linux can delay in prepare based on
  "hpd-gpios"
- ti-sn65dsi86 bindings (and current user) now specifies "no-hpd"
  if HPD isn't hooked up.

Changes in v2:
- ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")
- ("dt-bindings: display: Add hpd-gpios to panel-common...") new for v2
- ("simple...hpd-gpios") is 1/2 of replacement for ("Allow...bridge GPIOs")
- specification => specifier.
- power up => power.
- Added back missing suspend-gpios.
- data-lanes and lane-polarities are are the right place now.
- endpoints don't need to be patternProperties.
- Specified more details for data-lanes and lane-polarities.
- Added old example back in, fixing bugs in it.
- Example i2c bus is just called "i2c", not "i2c1" now.
- ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd") new for v2.
- ("arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza") new for v2.

Douglas Anderson (6):
  drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux
  dt-bindings: display: Add hpd-gpios to panel-common bindings
  drm/panel-simple: Support hpd-gpios for delaying prepare()
  dt-bindings: drm/bridge: ti-sn65dsi86: Convert to yaml
  dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd
  arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza

 .../bindings/display/bridge/ti,sn65dsi86.txt  |  87 ------
 .../bindings/display/bridge/ti,sn65dsi86.yaml | 285 ++++++++++++++++++
 .../bindings/display/panel/panel-common.yaml  |   6 +
 arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi    |   2 +
 drivers/gpu/drm/bridge/ti-sn65dsi86.c         | 165 ++++++++++
 drivers/gpu/drm/panel/panel-simple.c          |  53 ++++
 6 files changed, 511 insertions(+), 87 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt
 create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml

-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply	[flat|nested] 14+ messages in thread

* [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-22 10:23   ` Stephen Boyd
  2020-04-21  5:06 ` [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings Douglas Anderson
                   ` (4 subsequent siblings)
  5 siblings, 1 reply; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, linux-kernel

The ti-sn65dsi86 MIPI DSI to eDP bridge chip has 4 pins on it that can
be used as GPIOs in a system.  Each pin can be configured as input,
output, or a special function for the bridge chip.  These are:
- GPIO1: SUSPEND Input
- GPIO2: DSIA VSYNC
- GPIO3: DSIA HSYNC or VSYNC
- GPIO4: PWM

Let's expose these pins as GPIOs.  A few notes:
- Access to ti-sn65dsi86 is via i2c so we set "can_sleep".
- These pins can't be configured for IRQ.
- There are no programmable pulls or other fancy features.
- Keeping the bridge chip powered might be expensive.  The driver is
  setup such that if all used GPIOs are only inputs we'll power the
  bridge chip on just long enough to read the GPIO and then power it
  off again.  Setting a GPIO as output will keep the bridge powered.
- If someone releases a GPIO we'll implicitly switch it to an input so
  we no longer need to keep the bridge powered for it.

Becaue of all of the above limitations we just need to implement a
bare-bones GPIO driver.  The device tree bindings already account for
this device being a GPIO controller so we only need the driver changes
for it.

NOTE: Despite the fact that these pins are nominally muxable I don't
believe it makes sense to expose them through the pinctrl interface as
well as the GPIO interface.  The special functions are things that the
bridge chip driver itself would care about and it can just configure
the pins as needed.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---

Changes in v2:
- ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")

 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 165 ++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 6ad688b320ae..d04c2b83d699 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -7,6 +7,8 @@
 #include <linux/clk.h>
 #include <linux/debugfs.h>
 #include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
@@ -54,6 +56,13 @@
 #define  BPP_18_RGB				BIT(0)
 #define SN_HPD_DISABLE_REG			0x5C
 #define  HPD_DISABLE				BIT(0)
+#define SN_GPIO_IO_REG				0x5E
+#define  SN_GPIO_INPUT_SHIFT			4
+#define  SN_GPIO_OUTPUT_SHIFT			0
+#define SN_GPIO_CTRL_REG			0x5F
+#define  SN_GPIO_MUX_INPUT			0
+#define  SN_GPIO_MUX_OUTPUT			1
+#define  SN_GPIO_MUX_SPECIAL			2
 #define SN_AUX_WDATA_REG(x)			(0x64 + (x))
 #define SN_AUX_ADDR_19_16_REG			0x74
 #define SN_AUX_ADDR_15_8_REG			0x75
@@ -102,6 +111,9 @@ struct ti_sn_bridge {
 	struct gpio_desc		*enable_gpio;
 	struct regulator_bulk_data	supplies[SN_REGULATOR_SUPPLY_NUM];
 	int				dp_lanes;
+
+	struct gpio_chip		gchip;
+	atomic_t			gchip_output;
 };
 
 static const struct regmap_range ti_sn_bridge_volatile_ranges[] = {
@@ -874,6 +886,153 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
 	return 0;
 }
 
+static struct ti_sn_bridge *gchip_to_pdata(struct gpio_chip *chip)
+{
+	return container_of(chip, struct ti_sn_bridge, gchip);
+}
+
+static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip,
+					   unsigned int offset)
+{
+	struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
+
+	return (atomic_read(&pdata->gchip_output) & BIT(offset)) ?
+		GPIOF_DIR_OUT : GPIOF_DIR_IN;
+}
+
+static int ti_sn_bridge_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
+	unsigned int val;
+	int ret;
+
+	/*
+	 * When the pin is an input we don't forcibly keep the bridge
+	 * powered--we just power it on to read the pin.  NOTE: part of
+	 * the reason this works is that the bridge defaults to all 4
+	 * GPIOs being configured as GPIO input.  Also note that if
+	 * something else is keeping the chip powered the pm_runtime
+	 * functions are lightweight increments of a refcount.
+	 */
+	pm_runtime_get_sync(pdata->dev);
+	ret = regmap_read(pdata->regmap, SN_GPIO_IO_REG, &val);
+	pm_runtime_put(pdata->dev);
+
+	if (ret)
+		return ret;
+
+	return (val >> (SN_GPIO_INPUT_SHIFT + offset)) & 1;
+}
+
+static void ti_sn_bridge_gpio_set(struct gpio_chip *chip, unsigned int offset,
+				  int val)
+{
+	struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
+	int ret;
+
+	if (!(atomic_read(&pdata->gchip_output) & BIT(offset))) {
+		dev_err(pdata->dev, "Ignoring GPIO set while input\n");
+		return;
+	}
+
+	val &= 1;
+	ret = regmap_update_bits(pdata->regmap, SN_GPIO_IO_REG,
+				 BIT(SN_GPIO_OUTPUT_SHIFT + offset),
+				 val << (SN_GPIO_OUTPUT_SHIFT + offset));
+}
+
+static int ti_sn_bridge_gpio_direction_input(struct gpio_chip *chip,
+					     unsigned int offset)
+{
+	struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
+	int shift = offset * 2;
+	int old_gchip_output;
+	int ret;
+
+	old_gchip_output = atomic_fetch_andnot(BIT(offset),
+					       &pdata->gchip_output);
+	if (!(old_gchip_output & BIT(offset)))
+		return 0;
+
+	ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG,
+				 0x3 << shift, SN_GPIO_MUX_INPUT << shift);
+	if (ret) {
+		atomic_or(BIT(offset), &pdata->gchip_output);
+		return ret;
+	}
+
+	pm_runtime_put(pdata->dev);
+
+	return 0;
+}
+
+static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip,
+					      unsigned int offset, int val)
+{
+	struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
+	int shift = offset * 2;
+	int old_gchip_output;
+	int ret;
+
+	old_gchip_output = atomic_fetch_or(BIT(offset), &pdata->gchip_output);
+	if (old_gchip_output & BIT(offset))
+		return 0;
+
+	pm_runtime_get_sync(pdata->dev);
+
+	/* Set value first to avoid glitching */
+	ti_sn_bridge_gpio_set(chip, offset, val);
+
+	/* Set direction */
+	ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG,
+				 0x3 << shift, SN_GPIO_MUX_OUTPUT << shift);
+	if (ret) {
+		atomic_andnot(BIT(offset), &pdata->gchip_output);
+		pm_runtime_put(pdata->dev);
+	}
+
+	return ret;
+}
+
+static void ti_sn_bridge_gpio_free(struct gpio_chip *chip, unsigned int offset)
+{
+	/* We won't keep pm_runtime if we're input, so switch there on free */
+	ti_sn_bridge_gpio_direction_input(chip, offset);
+}
+
+static const char * const ti_sn_bridge_gpio_names[] = {
+	"GPIO1", "GPIO2", "GPIO3", "GPIO4"
+};
+
+static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata)
+{
+	int ret;
+
+	/* Only init if someone is going to use us as a GPIO controller */
+	if (!of_property_read_bool(pdata->dev->of_node, "gpio-controller"))
+		return 0;
+
+	pdata->gchip.label = dev_name(pdata->dev);
+	pdata->gchip.parent = pdata->dev;
+	pdata->gchip.owner = THIS_MODULE;
+	pdata->gchip.free = ti_sn_bridge_gpio_free;
+	pdata->gchip.get_direction = ti_sn_bridge_gpio_get_direction;
+	pdata->gchip.direction_input = ti_sn_bridge_gpio_direction_input;
+	pdata->gchip.direction_output = ti_sn_bridge_gpio_direction_output;
+	pdata->gchip.get = ti_sn_bridge_gpio_get;
+	pdata->gchip.set = ti_sn_bridge_gpio_set;
+	pdata->gchip.can_sleep = true;
+	pdata->gchip.names = ti_sn_bridge_gpio_names;
+	pdata->gchip.ngpio = ARRAY_SIZE(ti_sn_bridge_gpio_names);
+	ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
+	if (ret) {
+		dev_err(pdata->dev, "can't add gpio chip\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static int ti_sn_bridge_probe(struct i2c_client *client,
 			      const struct i2c_device_id *id)
 {
@@ -937,6 +1096,12 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
 
 	pm_runtime_enable(pdata->dev);
 
+	ret = ti_sn_setup_gpio_controller(pdata);
+	if (ret) {
+		pm_runtime_disable(pdata->dev);
+		return ret;
+	}
+
 	i2c_set_clientdata(client, pdata);
 
 	pdata->aux.name = "ti-sn65dsi86-aux";
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-22 10:24   ` Stephen Boyd
  2020-04-21  5:06 ` [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare() Douglas Anderson
                   ` (3 subsequent siblings)
  5 siblings, 1 reply; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, Sam Ravnborg, Thierry Reding, linux-kernel

In the cases where there is no connector in a system there's no great
place to put "hpd-gpios".  As per discussion [1] the best place to put
it is in the panel.  Add this to the device tree bindings.

[1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("dt-bindings: display: Add hpd-gpios to panel-common...") new for v2

 .../devicetree/bindings/display/panel/panel-common.yaml     | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/panel-common.yaml b/Documentation/devicetree/bindings/display/panel/panel-common.yaml
index ed051ba12084..e9a04a3a4f5f 100644
--- a/Documentation/devicetree/bindings/display/panel/panel-common.yaml
+++ b/Documentation/devicetree/bindings/display/panel/panel-common.yaml
@@ -96,6 +96,12 @@ properties:
       (hot plug detect) signal, but the signal isn't hooked up so we should
       hardcode the max delay from the panel spec when powering up the panel.
 
+  hpd-gpios:
+    maxItems: 1
+    description:
+      If Hot Plug Detect (HPD) is connected to a GPIO in the system rather
+      than a dedicated HPD pin the pin can be specified here.
+
   # Control I/Os
 
   # Many display panels can be controlled through pins driven by GPIOs. The nature
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare()
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-22 21:12   ` Stephen Boyd
  2020-04-21  5:06 ` [PATCH v2 4/6] dt-bindings: drm/bridge: ti-sn65dsi86: Convert to yaml Douglas Anderson
                   ` (2 subsequent siblings)
  5 siblings, 1 reply; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, Sam Ravnborg, Thierry Reding, linux-kernel

People use panel-simple when they have panels that are builtin to
their device.  In these cases the HPD (Hot Plug Detect) signal isn't
really used for hotplugging devices but instead is used for power
sequencing.  Panel timing diagrams (especially for eDP panels) usually
have the HPD signal in them and it acts as an indicator that the panel
is ready for us to talk to it.

Sometimes the HPD signal is hooked up to a normal GPIO on a system.
In this case we need to poll it in the correct place to know that the
panel is ready for us.  In some system designs the right place for
this is panel-simple.

When adding this support, we'll account for the case that there might
be a circular dependency between panel-simple and the provider of the
GPIO.  The case this was designed for was for the "ti-sn65dsi86"
bridge chip.  If HPD is hooked up to one of the GPIOs provided by the
bridge chip then in our probe function we'll always get back
-EPROBE_DEFER.  Let's handle this by allowing this GPIO to show up
late if we saw -EPROBE_DEFER during probe.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("simple...hpd-gpios") is 1/2 of replacement for ("Allow...bridge GPIOs")

 drivers/gpu/drm/panel/panel-simple.c | 53 ++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 3ad828eaefe1..f816e2aa29cd 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -23,6 +23,7 @@
 
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
@@ -108,6 +109,7 @@ struct panel_simple {
 	struct i2c_adapter *ddc;
 
 	struct gpio_desc *enable_gpio;
+	struct gpio_desc *hpd_gpio;
 
 	struct drm_display_mode override_mode;
 };
@@ -259,11 +261,37 @@ static int panel_simple_unprepare(struct drm_panel *panel)
 	return 0;
 }
 
+static int panel_simple_get_hpd_gpio(struct device *dev,
+				     struct panel_simple *p, bool from_probe)
+{
+	int err;
+
+	p->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);
+	if (IS_ERR(p->hpd_gpio)) {
+		err = PTR_ERR(p->hpd_gpio);
+
+		/*
+		 * If we're called from probe we won't consider '-EPROBE_DEFER'
+		 * to be an error--we'll leave the error code in "hpd_gpio".
+		 * When we try to use it we'll try again.  This allows for
+		 * circular dependencies where the component providing the
+		 * hpd gpio needs the panel to init before probing.
+		 */
+		if (err != -EPROBE_DEFER || !from_probe) {
+			dev_err(dev, "failed to get 'hpd' GPIO: %d\n", err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 static int panel_simple_prepare(struct drm_panel *panel)
 {
 	struct panel_simple *p = to_panel_simple(panel);
 	unsigned int delay;
 	int err;
+	int hpd_asserted;
 
 	if (p->prepared)
 		return 0;
@@ -282,6 +310,26 @@ static int panel_simple_prepare(struct drm_panel *panel)
 	if (delay)
 		msleep(delay);
 
+	if (p->hpd_gpio) {
+		if (IS_ERR(p->hpd_gpio)) {
+			err = panel_simple_get_hpd_gpio(panel->dev, p, false);
+			if (err)
+				return err;
+		}
+
+		err = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio,
+					 hpd_asserted, hpd_asserted,
+					 1000, 2000000);
+		if (hpd_asserted < 0)
+			err = hpd_asserted;
+
+		if (err) {
+			dev_err(panel->dev,
+				"error waiting for hpd GPIO: %d\n", err);
+			return err;
+		}
+	}
+
 	p->prepared = true;
 
 	return 0;
@@ -462,6 +510,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	panel->desc = desc;
 
 	panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
+	if (!panel->no_hpd) {
+		err = panel_simple_get_hpd_gpio(dev, panel, true);
+		if (err)
+			return err;
+	}
 
 	panel->supply = devm_regulator_get(dev, "power");
 	if (IS_ERR(panel->supply))
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* [PATCH v2 4/6] dt-bindings: drm/bridge: ti-sn65dsi86: Convert to yaml
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
                   ` (2 preceding siblings ...)
  2020-04-21  5:06 ` [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare() Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Douglas Anderson
  2020-04-21  5:06 ` [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza Douglas Anderson
  5 siblings, 0 replies; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, Krzysztof Kozlowski, Paul Walmsley,
	Stephen Boyd, linux-kernel

This moves the bindings over, based a lot on toshiba,tc358768.yaml.
Unless there's someone known to be better, I've set the maintainer in
the yaml as the first person to submit bindings.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- specification => specifier.
- power up => power.
- Added back missing suspend-gpios.
- data-lanes and lane-polarities are are the right place now.
- endpoints don't need to be patternProperties.
- Specified more details for data-lanes and lane-polarities.
- Added old example back in, fixing bugs in it.
- Example i2c bus is just called "i2c", not "i2c1" now.

 .../bindings/display/bridge/ti,sn65dsi86.txt  |  87 ------
 .../bindings/display/bridge/ti,sn65dsi86.yaml | 279 ++++++++++++++++++
 2 files changed, 279 insertions(+), 87 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt
 create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt
deleted file mode 100644
index 8ec4a7f2623a..000000000000
--- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt
+++ /dev/null
@@ -1,87 +0,0 @@
-SN65DSI86 DSI to eDP bridge chip
---------------------------------
-
-This is the binding for Texas Instruments SN65DSI86 bridge.
-http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=sn65dsi86&fileType=pdf
-
-Required properties:
-- compatible: Must be "ti,sn65dsi86"
-- reg: i2c address of the chip, 0x2d as per datasheet
-- enable-gpios: gpio specification for bridge_en pin (active high)
-
-- vccio-supply: A 1.8V supply that powers up the digital IOs.
-- vpll-supply: A 1.8V supply that powers up the displayport PLL.
-- vcca-supply: A 1.2V supply that powers up the analog circuits.
-- vcc-supply: A 1.2V supply that powers up the digital core.
-
-Optional properties:
-- interrupts-extended: Specifier for the SN65DSI86 interrupt line.
-
-- gpio-controller: Marks the device has a GPIO controller.
-- #gpio-cells    : Should be two. The first cell is the pin number and
-                   the second cell is used to specify flags.
-                   See ../../gpio/gpio.txt for more information.
-- #pwm-cells : Should be one. See ../../pwm/pwm.yaml for description of
-               the cell formats.
-
-- clock-names: should be "refclk"
-- clocks: Specification for input reference clock. The reference
-	  clock rate must be 12 MHz, 19.2 MHz, 26 MHz, 27 MHz or 38.4 MHz.
-
-- data-lanes: See ../../media/video-interface.txt
-- lane-polarities: See ../../media/video-interface.txt
-
-- suspend-gpios: specification for GPIO1 pin on bridge (active low)
-
-Required nodes:
-This device has two video ports. Their connections are modelled using the
-OF graph bindings specified in Documentation/devicetree/bindings/graph.txt.
-
-- Video port 0 for DSI input
-- Video port 1 for eDP output
-
-Example
--------
-
-edp-bridge@2d {
-	compatible = "ti,sn65dsi86";
-	#address-cells = <1>;
-	#size-cells = <0>;
-	reg = <0x2d>;
-
-	enable-gpios = <&msmgpio 33 GPIO_ACTIVE_HIGH>;
-	suspend-gpios = <&msmgpio 34 GPIO_ACTIVE_LOW>;
-
-	interrupts-extended = <&gpio3 4 IRQ_TYPE_EDGE_FALLING>;
-
-	vccio-supply = <&pm8916_l17>;
-	vcca-supply = <&pm8916_l6>;
-	vpll-supply = <&pm8916_l17>;
-	vcc-supply = <&pm8916_l6>;
-
-	clock-names = "refclk";
-	clocks = <&input_refclk>;
-
-	ports {
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		port@0 {
-			reg = <0>;
-
-			edp_bridge_in: endpoint {
-				remote-endpoint = <&dsi_out>;
-			};
-		};
-
-		port@1 {
-			reg = <1>;
-
-			edp_bridge_out: endpoint {
-				data-lanes = <2 1 3 0>;
-				lane-polarities = <0 1 0 1>;
-				remote-endpoint = <&edp_panel_in>;
-			};
-		};
-	};
-}
diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
new file mode 100644
index 000000000000..6d7d40ad45ac
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
@@ -0,0 +1,279 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/ti,sn65dsi86.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SN65DSI86 DSI to eDP bridge chip
+
+maintainers:
+  - Sandeep Panda <spanda@codeaurora.org>
+
+description: |
+  The Texas Instruments SN65DSI86 bridge takes MIPI DSI in and outputs eDP.
+  http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=sn65dsi86&fileType=pdf
+
+properties:
+  compatible:
+    const: ti,sn65dsi86
+
+  reg:
+    const: 0x2d
+
+  enable-gpios:
+    maxItems: 1
+    description: GPIO specifier for bridge_en pin (active high).
+
+  suspend-gpios:
+    maxItems: 1
+    description: GPIO specifier for GPIO1 pin on bridge (active low).
+
+  vccio-supply:
+    description: A 1.8V supply that powers the digital IOs.
+
+  vpll-supply:
+    description: A 1.8V supply that powers the DisplayPort PLL.
+
+  vcca-supply:
+    description: A 1.2V supply that powers the analog circuits.
+
+  vcc-supply:
+    description: A 1.2V supply that powers the digital core.
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description:
+      Clock specifier for input reference clock. The reference clock rate must
+      be 12 MHz, 19.2 MHz, 26 MHz, 27 MHz or 38.4 MHz.
+
+  clock-names:
+    const: refclk
+
+  gpio-controller: true
+  '#gpio-cells':
+    const: 2
+    description:
+      First cell is pin number, second cell is flags.  GPIO pin numbers are
+      1-based to match the datasheet.  See ../../gpio/gpio.txt for more
+      information.
+
+  '#pwm-cells':
+    const: 1
+    description: See ../../pwm/pwm.yaml for description of the cell formats.
+
+  ports:
+    type: object
+
+    properties:
+      "#address-cells":
+        const: 1
+
+      "#size-cells":
+        const: 0
+
+      port@0:
+        type: object
+        additionalProperties: false
+
+        description:
+          Video port for MIPI DSI input
+
+        properties:
+          reg:
+            const: 0
+
+          endpoint:
+            type: object
+            additionalProperties: false
+
+            properties:
+              remote-endpoint: true
+
+              data-lanes:
+                minItems: 1
+                maxItems: 4
+                items:
+                  enum:
+                    - 0
+                    - 1
+                    - 2
+                    - 3
+                description: See ../../media/video-interface.txt
+
+              lane-polarities:
+                minItems: 1
+                maxItems: 4
+                items:
+                  enum:
+                    - 0
+                    - 1
+                description: See ../../media/video-interface.txt
+
+            dependencies:
+              data-lanes: [lane-polarities]
+
+        required:
+          - reg
+
+      port@1:
+        type: object
+        additionalProperties: false
+
+        description:
+          Video port for eDP output (panel or connector).
+
+        properties:
+          reg:
+            const: 1
+
+          endpoint:
+            type: object
+            additionalProperties: false
+
+            properties:
+              remote-endpoint: true
+
+              data-lanes:
+                minItems: 1
+                maxItems: 4
+                items:
+                  enum:
+                    - 0
+                    - 1
+                    - 2
+                    - 3
+                description: See ../../media/video-interface.txt
+
+              lane-polarities:
+                minItems: 1
+                maxItems: 4
+                items:
+                  enum:
+                    - 0
+                    - 1
+                description: See ../../media/video-interface.txt
+
+            dependencies:
+              data-lanes: [lane-polarities]
+
+        required:
+          - reg
+
+    required:
+      - "#address-cells"
+      - "#size-cells"
+      - port@0
+      - port@1
+
+required:
+  - compatible
+  - reg
+  - enable-gpios
+  - vccio-supply
+  - vpll-supply
+  - vcca-supply
+  - vcc-supply
+  - ports
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,rpmh.h>
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      bridge@2d {
+        compatible = "ti,sn65dsi86";
+        reg = <0x2d>;
+
+        interrupt-parent = <&tlmm>;
+        interrupts = <10 IRQ_TYPE_LEVEL_HIGH>;
+
+        enable-gpios = <&tlmm 102 GPIO_ACTIVE_HIGH>;
+
+        vpll-supply = <&src_pp1800_s4a>;
+        vccio-supply = <&src_pp1800_s4a>;
+        vcca-supply = <&src_pp1200_l2a>;
+        vcc-supply = <&src_pp1200_l2a>;
+
+        clocks = <&rpmhcc RPMH_LN_BB_CLK2>;
+        clock-names = "refclk";
+
+        ports {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          port@0 {
+            reg = <0>;
+            endpoint {
+              remote-endpoint = <&dsi0_out>;
+            };
+          };
+
+          port@1 {
+            reg = <1>;
+            endpoint {
+              remote-endpoint = <&panel_in_edp>;
+            };
+          };
+        };
+      };
+    };
+  - |
+    #include <dt-bindings/clock/qcom,rpmh.h>
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      bridge@2d {
+        compatible = "ti,sn65dsi86";
+        reg = <0x2d>;
+
+        enable-gpios = <&msmgpio 33 GPIO_ACTIVE_HIGH>;
+        suspend-gpios = <&msmgpio 34 GPIO_ACTIVE_LOW>;
+
+        interrupts-extended = <&gpio3 4 IRQ_TYPE_EDGE_FALLING>;
+
+        vccio-supply = <&pm8916_l17>;
+        vcca-supply = <&pm8916_l6>;
+        vpll-supply = <&pm8916_l17>;
+        vcc-supply = <&pm8916_l6>;
+
+        clock-names = "refclk";
+        clocks = <&input_refclk>;
+
+        ports {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          port@0 {
+            reg = <0>;
+
+            edp_bridge_in: endpoint {
+              remote-endpoint = <&dsi_out>;
+            };
+          };
+
+          port@1 {
+            reg = <1>;
+
+            edp_bridge_out: endpoint {
+              data-lanes = <2 1 3 0>;
+              lane-polarities = <0 1 0 1>;
+              remote-endpoint = <&edp_panel_in>;
+            };
+          };
+        };
+      };
+    };
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
                   ` (3 preceding siblings ...)
  2020-04-21  5:06 ` [PATCH v2 4/6] dt-bindings: drm/bridge: ti-sn65dsi86: Convert to yaml Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-22 10:26   ` Stephen Boyd
  2020-04-21  5:06 ` [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza Douglas Anderson
  5 siblings, 1 reply; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, linux-kernel

The ti-sn65dsi86 MIPI DSI to eDP bridge chip has a dedicated hardware
HPD (Hot Plug Detect) pin on it, but it's mostly useless for eDP
because of excessive debouncing in hardware.  Specifically there is no
way to disable the debouncing and for eDP debouncing hurts you because
HPD is just used for knowing when the panel is ready, not for
detecting physical plug events.

Currently the driver in Linux just assumes that nobody has HPD hooked
up.  It relies on folks setting the "no-hpd" property in the panel
node to specify that HPD isn't hooked up and then the panel driver
using this to add some worst case delays when turning on the panel.

Apparently it's also useful to specify "no-hpd" in the bridge node so
that the bridge driver can make sure it's doing the right thing
without peeking into the panel [1].  This would be used if anyone ever
found it useful implement support for the HW HPD pin on the bridge.
Let's add this property to the bindings.

NOTES:
- This is somewhat of a backward-incompatible change.  All current
  known users of ti-sn65dsi86 didn't have "no-hpd" specified in the
  bridge node yet none of them had HPD hooked up.  This worked because
  the current Linux driver just assumed that HPD was never hooked up.
  We could make it less incompatible by saying that for this bridge
  it's assumed HPD isn't hooked up _unless_ a property is defined, but
  "no-hpd" is much more standard and it's unlikely to matter unless
  someone quickly goes and implements HPD in the driver.
- It is sensible to specify "no-hpd" at the bridge chip level and
  specify "hpd-gpios" at the panel level.  That would mean HPD is
  hooked up to some other GPIO in the system, just not the hardware
  HPD pin on the bridge chip.

[1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd") new for v2.

 .../devicetree/bindings/display/bridge/ti,sn65dsi86.yaml    | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
index 6d7d40ad45ac..5746416b0f73 100644
--- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
@@ -28,6 +28,10 @@ properties:
     maxItems: 1
     description: GPIO specifier for GPIO1 pin on bridge (active low).
 
+  no-hpd:
+    type: boolean
+    description: Set if the HPD line on the bridge isn't hooked up to anything.
+
   vccio-supply:
     description: A 1.8V supply that powers the digital IOs.
 
@@ -207,6 +211,8 @@ examples:
         clocks = <&rpmhcc RPMH_LN_BB_CLK2>;
         clock-names = "refclk";
 
+        no-hpd;
+
         ports {
           #address-cells = <1>;
           #size-cells = <0>;
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza
  2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
                   ` (4 preceding siblings ...)
  2020-04-21  5:06 ` [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Douglas Anderson
@ 2020-04-21  5:06 ` Douglas Anderson
  2020-04-22 10:26   ` Stephen Boyd
  5 siblings, 1 reply; 14+ messages in thread
From: Douglas Anderson @ 2020-04-21  5:06 UTC (permalink / raw)
  To: linus.walleij, bgolaszewski, airlied, daniel, robh+dt,
	narmstrong, a.hajda, Laurent.pinchart, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, swboyd, bjorn.andersson, robdclark,
	Douglas Anderson, Andy Gross, linux-kernel

We don't have the HPD line hooked up to the bridge chip.  Add it as
suggested in the patch ("dt-bindings: drm/bridge: ti-sn65dsi86:
Document no-hpd").

NOTE: this patch isn't expected to have any effect but just keeps us
cleaner for the future.  Currently the driver in Linux just assumes
that nobody has HPD hooked up.  This change allows us to later
implement HPD support in the driver without messing up sdm845-cheza.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza") new for v2.

 arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi b/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi
index 9070be43a309..5938f8b2aa2f 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi
+++ b/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi
@@ -548,6 +548,8 @@ sn65dsi86_bridge: bridge@2d {
 		clocks = <&rpmhcc RPMH_LN_BB_CLK2>;
 		clock-names = "refclk";
 
+		no-hpd;
+
 		ports {
 			#address-cells = <1>;
 			#size-cells = <0>;
-- 
2.26.1.301.g55bc3eb7cb9-goog


^ permalink raw reply related	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux
  2020-04-21  5:06 ` [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Douglas Anderson
@ 2020-04-22 10:23   ` Stephen Boyd
  2020-04-22 16:09     ` Doug Anderson
  0 siblings, 1 reply; 14+ messages in thread
From: Stephen Boyd @ 2020-04-22 10:23 UTC (permalink / raw)
  To: Douglas Anderson, Laurent.pinchart, a.hajda, airlied,
	bgolaszewski, daniel, linus.walleij, narmstrong, robh+dt, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, bjorn.andersson, robdclark,
	Douglas Anderson, linux-kernel

Quoting Douglas Anderson (2020-04-20 22:06:17)
> The ti-sn65dsi86 MIPI DSI to eDP bridge chip has 4 pins on it that can
> be used as GPIOs in a system.  Each pin can be configured as input,
> output, or a special function for the bridge chip.  These are:
> - GPIO1: SUSPEND Input
> - GPIO2: DSIA VSYNC
> - GPIO3: DSIA HSYNC or VSYNC
> - GPIO4: PWM
> 
> Let's expose these pins as GPIOs.  A few notes:
> - Access to ti-sn65dsi86 is via i2c so we set "can_sleep".
> - These pins can't be configured for IRQ.
> - There are no programmable pulls or other fancy features.
> - Keeping the bridge chip powered might be expensive.  The driver is
>   setup such that if all used GPIOs are only inputs we'll power the
>   bridge chip on just long enough to read the GPIO and then power it
>   off again.  Setting a GPIO as output will keep the bridge powered.
> - If someone releases a GPIO we'll implicitly switch it to an input so
>   we no longer need to keep the bridge powered for it.
> 
> Becaue of all of the above limitations we just need to implement a

Because

> bare-bones GPIO driver.  The device tree bindings already account for
> this device being a GPIO controller so we only need the driver changes
> for it.
> 
> NOTE: Despite the fact that these pins are nominally muxable I don't
> believe it makes sense to expose them through the pinctrl interface as
> well as the GPIO interface.  The special functions are things that the
> bridge chip driver itself would care about and it can just configure
> the pins as needed.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> 

Cool patch.

> Changes in v2:
> - ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")
> 
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 165 ++++++++++++++++++++++++++
>  1 file changed, 165 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 6ad688b320ae..d04c2b83d699 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -874,6 +886,153 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
>         return 0;
>  }
>  
> +static struct ti_sn_bridge *gchip_to_pdata(struct gpio_chip *chip)
> +{
> +       return container_of(chip, struct ti_sn_bridge, gchip);
> +}
> +
> +static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip,
> +                                          unsigned int offset)
> +{
> +       struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
> +
> +       return (atomic_read(&pdata->gchip_output) & BIT(offset)) ?

Any reason this isn't a bitmap?

> +               GPIOF_DIR_OUT : GPIOF_DIR_IN;

And why can't we read the hardware to figure out if it's in output or
input mode?

> +}
> +
[...]
> +static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip,
> +                                             unsigned int offset, int val)
> +{
> +       struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
> +       int shift = offset * 2;
> +       int old_gchip_output;
> +       int ret;
> +
> +       old_gchip_output = atomic_fetch_or(BIT(offset), &pdata->gchip_output);

I presume gpiolib is already preventing a gpio from being modified twice
at the same time. So is this atomic stuff really necessary?

> +       if (old_gchip_output & BIT(offset))
> +               return 0;
> +
> +       pm_runtime_get_sync(pdata->dev);
> +
> +       /* Set value first to avoid glitching */
> +       ti_sn_bridge_gpio_set(chip, offset, val);
> +
> +       /* Set direction */
> +       ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG,
> +                                0x3 << shift, SN_GPIO_MUX_OUTPUT << shift);
> +       if (ret) {
> +               atomic_andnot(BIT(offset), &pdata->gchip_output);
> +               pm_runtime_put(pdata->dev);
> +       }
> +
> +       return ret;
> +}
> +
> +static void ti_sn_bridge_gpio_free(struct gpio_chip *chip, unsigned int offset)
> +{
> +       /* We won't keep pm_runtime if we're input, so switch there on free */
> +       ti_sn_bridge_gpio_direction_input(chip, offset);
> +}
> +
> +static const char * const ti_sn_bridge_gpio_names[] = {
> +       "GPIO1", "GPIO2", "GPIO3", "GPIO4"
> +};
> +
> +static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata)
> +{
[...]
> +       pdata->gchip.names = ti_sn_bridge_gpio_names;
> +       pdata->gchip.ngpio = ARRAY_SIZE(ti_sn_bridge_gpio_names);
> +       ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
> +       if (ret) {
> +               dev_err(pdata->dev, "can't add gpio chip\n");
> +               return ret;
> +       }
> +
> +       return 0;

return ret?

> +}
> +
>  static int ti_sn_bridge_probe(struct i2c_client *client,
>                               const struct i2c_device_id *id)
>  {

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings
  2020-04-21  5:06 ` [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings Douglas Anderson
@ 2020-04-22 10:24   ` Stephen Boyd
  0 siblings, 0 replies; 14+ messages in thread
From: Stephen Boyd @ 2020-04-22 10:24 UTC (permalink / raw)
  To: Douglas Anderson, Laurent.pinchart, a.hajda, airlied,
	bgolaszewski, daniel, linus.walleij, narmstrong, robh+dt, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, bjorn.andersson, robdclark,
	Douglas Anderson, Sam Ravnborg, Thierry Reding, linux-kernel

Quoting Douglas Anderson (2020-04-20 22:06:18)
> In the cases where there is no connector in a system there's no great
> place to put "hpd-gpios".  As per discussion [1] the best place to put
> it is in the panel.  Add this to the device tree bindings.
> 
> [1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd
  2020-04-21  5:06 ` [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Douglas Anderson
@ 2020-04-22 10:26   ` Stephen Boyd
  0 siblings, 0 replies; 14+ messages in thread
From: Stephen Boyd @ 2020-04-22 10:26 UTC (permalink / raw)
  To: Douglas Anderson, Laurent.pinchart, a.hajda, airlied,
	bgolaszewski, daniel, linus.walleij, narmstrong, robh+dt, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, bjorn.andersson, robdclark,
	Douglas Anderson, linux-kernel

Quoting Douglas Anderson (2020-04-20 22:06:21)
> The ti-sn65dsi86 MIPI DSI to eDP bridge chip has a dedicated hardware
> HPD (Hot Plug Detect) pin on it, but it's mostly useless for eDP
> because of excessive debouncing in hardware.  Specifically there is no
> way to disable the debouncing and for eDP debouncing hurts you because
> HPD is just used for knowing when the panel is ready, not for
> detecting physical plug events.
> 
> Currently the driver in Linux just assumes that nobody has HPD hooked
> up.  It relies on folks setting the "no-hpd" property in the panel
> node to specify that HPD isn't hooked up and then the panel driver
> using this to add some worst case delays when turning on the panel.
> 
> Apparently it's also useful to specify "no-hpd" in the bridge node so
> that the bridge driver can make sure it's doing the right thing
> without peeking into the panel [1].  This would be used if anyone ever
> found it useful implement support for the HW HPD pin on the bridge.

useful to implement?

> Let's add this property to the bindings.
> 
> NOTES:
> - This is somewhat of a backward-incompatible change.  All current
>   known users of ti-sn65dsi86 didn't have "no-hpd" specified in the
>   bridge node yet none of them had HPD hooked up.  This worked because
>   the current Linux driver just assumed that HPD was never hooked up.
>   We could make it less incompatible by saying that for this bridge
>   it's assumed HPD isn't hooked up _unless_ a property is defined, but
>   "no-hpd" is much more standard and it's unlikely to matter unless
>   someone quickly goes and implements HPD in the driver.
> - It is sensible to specify "no-hpd" at the bridge chip level and
>   specify "hpd-gpios" at the panel level.  That would mean HPD is
>   hooked up to some other GPIO in the system, just not the hardware
>   HPD pin on the bridge chip.
> 
> [1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza
  2020-04-21  5:06 ` [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza Douglas Anderson
@ 2020-04-22 10:26   ` Stephen Boyd
  0 siblings, 0 replies; 14+ messages in thread
From: Stephen Boyd @ 2020-04-22 10:26 UTC (permalink / raw)
  To: Douglas Anderson, Laurent.pinchart, a.hajda, airlied,
	bgolaszewski, daniel, linus.walleij, narmstrong, robh+dt, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, bjorn.andersson, robdclark,
	Douglas Anderson, Andy Gross, linux-kernel

Quoting Douglas Anderson (2020-04-20 22:06:22)
> We don't have the HPD line hooked up to the bridge chip.  Add it as
> suggested in the patch ("dt-bindings: drm/bridge: ti-sn65dsi86:
> Document no-hpd").
> 
> NOTE: this patch isn't expected to have any effect but just keeps us
> cleaner for the future.  Currently the driver in Linux just assumes
> that nobody has HPD hooked up.  This change allows us to later
> implement HPD support in the driver without messing up sdm845-cheza.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux
  2020-04-22 10:23   ` Stephen Boyd
@ 2020-04-22 16:09     ` Doug Anderson
       [not found]       ` <158758963395.230545.16210525372433383386@swboyd.mtv.corp.google.com>
  0 siblings, 1 reply; 14+ messages in thread
From: Doug Anderson @ 2020-04-22 16:09 UTC (permalink / raw)
  To: Stephen Boyd
  Cc: Laurent Pinchart, Andrzej Hajda, David Airlie, bgolaszewski,
	Daniel Vetter, LinusW, Neil Armstrong, Rob Herring,
	Sandeep Panda, Jonas Karlman, Jeffrey Hugo,
	open list:GPIO SUBSYSTEM, linux-arm-msm, dri-devel,
	open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS,
	Jernej Skrabec, Bjorn Andersson, Rob Clark, LKML

Hi,

On Wed, Apr 22, 2020 at 3:23 AM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Douglas Anderson (2020-04-20 22:06:17)
> > The ti-sn65dsi86 MIPI DSI to eDP bridge chip has 4 pins on it that can
> > be used as GPIOs in a system.  Each pin can be configured as input,
> > output, or a special function for the bridge chip.  These are:
> > - GPIO1: SUSPEND Input
> > - GPIO2: DSIA VSYNC
> > - GPIO3: DSIA HSYNC or VSYNC
> > - GPIO4: PWM
> >
> > Let's expose these pins as GPIOs.  A few notes:
> > - Access to ti-sn65dsi86 is via i2c so we set "can_sleep".
> > - These pins can't be configured for IRQ.
> > - There are no programmable pulls or other fancy features.
> > - Keeping the bridge chip powered might be expensive.  The driver is
> >   setup such that if all used GPIOs are only inputs we'll power the
> >   bridge chip on just long enough to read the GPIO and then power it
> >   off again.  Setting a GPIO as output will keep the bridge powered.
> > - If someone releases a GPIO we'll implicitly switch it to an input so
> >   we no longer need to keep the bridge powered for it.
> >
> > Becaue of all of the above limitations we just need to implement a
>
> Because
>
> > bare-bones GPIO driver.  The device tree bindings already account for
> > this device being a GPIO controller so we only need the driver changes
> > for it.
> >
> > NOTE: Despite the fact that these pins are nominally muxable I don't
> > believe it makes sense to expose them through the pinctrl interface as
> > well as the GPIO interface.  The special functions are things that the
> > bridge chip driver itself would care about and it can just configure
> > the pins as needed.
> >
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > Cc: Linus Walleij <linus.walleij@linaro.org>
> > Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > ---
> >
>
> Cool patch.
>
> > Changes in v2:
> > - ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")
> >
> >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 165 ++++++++++++++++++++++++++
> >  1 file changed, 165 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > index 6ad688b320ae..d04c2b83d699 100644
> > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > @@ -874,6 +886,153 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
> >         return 0;
> >  }
> >
> > +static struct ti_sn_bridge *gchip_to_pdata(struct gpio_chip *chip)
> > +{
> > +       return container_of(chip, struct ti_sn_bridge, gchip);
> > +}
> > +
> > +static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip,
> > +                                          unsigned int offset)
> > +{
> > +       struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
> > +
> > +       return (atomic_read(&pdata->gchip_output) & BIT(offset)) ?
>
> Any reason this isn't a bitmap?

Don't bitmaps need an external lock to protect against concurrent
access?  When I looked I wasn't convinced that the GPIO subsystem
prevented two callers from changing two GPIOs at the same time.  See
below for a bigger discussion.


> > +               GPIOF_DIR_OUT : GPIOF_DIR_IN;
>
> And why can't we read the hardware to figure out if it's in output or
> input mode?

A few reasons:

1. If nobody else had the bridge powered on this would be a slow
operation involving powering the bridge on, querying via i2c, and then
powering the bridge off.  Not only would it be slow but you'd be
powering the chip up for no really good reason.  You didn't need to
know anything that only the chip could tell you.

2. If nobody else had the bridge powered on then the bridge loses
state and resets to defaults (everything resets to "input").  Yes, we
could still power the bridge up and confirm this, but...

3. This bitmap does double-duty of not only knowing whether a pin is
input or output but also whether we've incremented the "pm_runtime"
refcount in order to keep the output driven.  Knowing whether we've
already incremented the "pm_runtime" refcount can simplify a bit of
the code because we know whether it's powered without having to power
it on and query.  If we didn't have a cache, then when we changed a
pin to input we'd do:

pm_runtime_get() // Make sure we can access
if dir_was_output:
  pm_runtime_put() // Not driving anymore
set_to_input();
pm_runtime_put()  // Done with access

...basically in some cases we'd do pm_runtime_put() twice in the same
function.  It'd work, but feels like a worse solution than the one in
my patch.

4. When I bootup I see that this call gets made once per GPIO in
gpiochip_add_data_with_key().  There's no reason to go through all the
slowness when we know these pins are inputs.


In the next version of the patch I'll plan to add a kerneldoc comment
to "struct ti_sn_bridge" and add a summary of the above for
"gchip_output".


> > +}
> > +
> [...]
> > +static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip,
> > +                                             unsigned int offset, int val)
> > +{
> > +       struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
> > +       int shift = offset * 2;
> > +       int old_gchip_output;
> > +       int ret;
> > +
> > +       old_gchip_output = atomic_fetch_or(BIT(offset), &pdata->gchip_output);
>
> I presume gpiolib is already preventing a gpio from being modified twice
> at the same time. So is this atomic stuff really necessary?

Right.  I've assumed that we're not running two of these functions at
the same time for the same GPIO.  I'm not convinced that the GPIO core
enforces this but it seems like it'd be undefined behavior for a
client to be, for instance, setting and changing direction for the
same GPIO in two threads at the same time.  Where simple I've tried to
make it so it wouldn't horribly break if someone did some amount of
concurrent access of the same pin but not every corner case is
handled.  Mostly I focused on making sure that I could never mess up
keeping track of whether I incremented the "pm_runtime" refcount for a
pin.  One thing specifically I didn't handle: if we were midway
through ti_sn_bridge_gpio_set(), we context switched out and someone
changed us to an input, then we'd possibly do an unpowered
regmap_update_bits() and timeout.

What I do think is a sensible case to handle, though, is someone
working with two different GPIOs exported by this controller at the
same time.  IIUC atomic_t allows me to only spend 1 bit per pin, have
no lock, and still make sure these different consumers don't stomp on
each other.

NOTE: I did a quick trace for the call chain when using the "gpioget"
command-line tool.  I saw:

- ti_sn_bridge_gpio_get()
- gpio_chip_get_multiple()
- gpiod_get_array_value_complex()
- linehandle_ioctl()

None of these appear to do any locking.  There's sorta an implicit
lock in that only one client can "request" a given GPIO at the same
time so the assumption that we're somewhat protected against two
concurrent accesses of the exact same GPIO is a bit justified.  ...but
nothing appears to protect us from concurrent accesses of different
GPIOs.

I also notice that other GPIO drivers seem to grab their own locks.
If it makes the patch more palatable, I can get rid of all the atomic
stuff and put in a big mutex?

-Doug

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare()
  2020-04-21  5:06 ` [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare() Douglas Anderson
@ 2020-04-22 21:12   ` Stephen Boyd
  0 siblings, 0 replies; 14+ messages in thread
From: Stephen Boyd @ 2020-04-22 21:12 UTC (permalink / raw)
  To: Douglas Anderson, Laurent.pinchart, a.hajda, airlied,
	bgolaszewski, daniel, linus.walleij, narmstrong, robh+dt, spanda
  Cc: jonas, jeffrey.l.hugo, linux-gpio, linux-arm-msm, dri-devel,
	devicetree, jernej.skrabec, bjorn.andersson, robdclark,
	Douglas Anderson, Sam Ravnborg, Thierry Reding, linux-kernel

Quoting Douglas Anderson (2020-04-20 22:06:19)
> People use panel-simple when they have panels that are builtin to
> their device.  In these cases the HPD (Hot Plug Detect) signal isn't
> really used for hotplugging devices but instead is used for power
> sequencing.  Panel timing diagrams (especially for eDP panels) usually
> have the HPD signal in them and it acts as an indicator that the panel
> is ready for us to talk to it.
> 
> Sometimes the HPD signal is hooked up to a normal GPIO on a system.
> In this case we need to poll it in the correct place to know that the
> panel is ready for us.  In some system designs the right place for
> this is panel-simple.
> 
> When adding this support, we'll account for the case that there might
> be a circular dependency between panel-simple and the provider of the
> GPIO.  The case this was designed for was for the "ti-sn65dsi86"
> bridge chip.  If HPD is hooked up to one of the GPIOs provided by the
> bridge chip then in our probe function we'll always get back
> -EPROBE_DEFER.  Let's handle this by allowing this GPIO to show up
> late if we saw -EPROBE_DEFER during probe.

May be worth mentioning that if there isn't an hpd-gpios property then
we only try once during probe and then after that the prepare callback
doesn't try again because the gpio_get_optional() APIs are used. I had
to think about that for a minute.

> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux
       [not found]       ` <158758963395.230545.16210525372433383386@swboyd.mtv.corp.google.com>
@ 2020-04-22 23:31         ` Doug Anderson
  0 siblings, 0 replies; 14+ messages in thread
From: Doug Anderson @ 2020-04-22 23:31 UTC (permalink / raw)
  To: Stephen Boyd
  Cc: Laurent Pinchart, Andrzej Hajda, David Airlie, bgolaszewski,
	Daniel Vetter, LinusW, Neil Armstrong, Rob Herring,
	Sandeep Panda, Jonas Karlman, Jeffrey Hugo,
	open list:GPIO SUBSYSTEM <linux-gpio@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
	<devicetree@vger.kernel.org>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Rob Clark <robdclark@chromium.org>,
	LKML

Hi,

On Wed, Apr 22, 2020 at 2:07 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Doug Anderson (2020-04-22 09:09:17)
> > Hi,
> >
> > On Wed, Apr 22, 2020 at 3:23 AM Stephen Boyd <swboyd@chromium.org> wrote:
> > >
> > > Quoting Douglas Anderson (2020-04-20 22:06:17)
> > >
> > > > Changes in v2:
> > > > - ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")
> > > >
> > > >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 165 ++++++++++++++++++++++++++
> > > >  1 file changed, 165 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > index 6ad688b320ae..d04c2b83d699 100644
> > > > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > @@ -874,6 +886,153 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
> > > >         return 0;
> > > >  }
> > > >
> > > > +static struct ti_sn_bridge *gchip_to_pdata(struct gpio_chip *chip)
> > > > +{
> > > > +       return container_of(chip, struct ti_sn_bridge, gchip);
> > > > +}
> > > > +
> > > > +static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip,
> > > > +                                          unsigned int offset)
> > > > +{
> > > > +       struct ti_sn_bridge *pdata = gchip_to_pdata(chip);
> > > > +
> > > > +       return (atomic_read(&pdata->gchip_output) & BIT(offset)) ?
> > >
> > > Any reason this isn't a bitmap?
> >
> > Don't bitmaps need an external lock to protect against concurrent
> > access?
>
> Bitmaps are sometimes atomic. See Documentation/atomic_bitops.txt for
> more info. From what I see here it looks like we can have a bitmap for
> this and then use set_bit(), test_and_set_bit(), etc. and it will be the
> same and easier to read.

Hrm.  Somehow I found the wrong place when trying to search for this
previously.  Thanks for pointing me in the right directions.  Much
nicer.


> > When I looked I wasn't convinced that the GPIO subsystem
> > prevented two callers from changing two GPIOs at the same time.  See
> > below for a bigger discussion.
> >
> >
> > > > +               GPIOF_DIR_OUT : GPIOF_DIR_IN;
> > >
> > > And why can't we read the hardware to figure out if it's in output or
> > > input mode?
> >
> [...]
> >
> > In the next version of the patch I'll plan to add a kerneldoc comment
> > to "struct ti_sn_bridge" and add a summary of the above for
> > "gchip_output".
>
> Yeah it deserves a comment in the code indicating why it doesn't read
> the hardware.

OK, added a whole bunch more comments.

Barring something coming up, I'll plan to send v3 tomorrow morning
with all your feedback addressed.  If anyone wants me to wait because
they think I need some more major change, please yell.


-Doug

^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2020-04-22 23:31 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-04-21  5:06 [PATCH v2 0/6] drm: Prepare to use a GPIO on ti-sn65dsi86 for Hot Plug Detect Douglas Anderson
2020-04-21  5:06 ` [PATCH v2 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Douglas Anderson
2020-04-22 10:23   ` Stephen Boyd
2020-04-22 16:09     ` Doug Anderson
     [not found]       ` <158758963395.230545.16210525372433383386@swboyd.mtv.corp.google.com>
2020-04-22 23:31         ` Doug Anderson
2020-04-21  5:06 ` [PATCH v2 2/6] dt-bindings: display: Add hpd-gpios to panel-common bindings Douglas Anderson
2020-04-22 10:24   ` Stephen Boyd
2020-04-21  5:06 ` [PATCH v2 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare() Douglas Anderson
2020-04-22 21:12   ` Stephen Boyd
2020-04-21  5:06 ` [PATCH v2 4/6] dt-bindings: drm/bridge: ti-sn65dsi86: Convert to yaml Douglas Anderson
2020-04-21  5:06 ` [PATCH v2 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Douglas Anderson
2020-04-22 10:26   ` Stephen Boyd
2020-04-21  5:06 ` [PATCH v2 6/6] arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza Douglas Anderson
2020-04-22 10:26   ` Stephen Boyd

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