[PATCH RESEND 0/4] drm: bridge: anx7688 and an optional feature

[PATCH RESEND 0/4] drm: bridge: anx7688 and an optional feature

[Hsin-Yi Wang]

[Resend to cc more reviewers]

This series is to add anx7688 bridge driver. It is extended from
previous work[1].

The first 2 patches are same as previous version, with some modification
due to drm core function changes and use regmap abstraction.

We add an optional feature bypass-gpios so that driver can decide if it serves
as simple pass-thru by reading GPIO values, which is controlled by
hardware.

[1] https://lore.kernel.org/lkml/1467013727-11482-1-git-send-email-drinkcat@chromium.org/

Hsin-Yi Wang (2):
  dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO
  drm: bridge: anx7688: Support bypass GPIO feature

Nicolas Boichat (2):
  dt-bindings: drm/bridge: analogix-anx7688: Add ANX7688 transmitter
    binding
  drm: bridge: anx7688: Add anx7688 bridge driver support.

 .../bindings/display/bridge/anx7688.txt       |  70 +++++
 drivers/gpu/drm/bridge/Kconfig                |   9 +
 drivers/gpu/drm/bridge/Makefile               |   1 +
 drivers/gpu/drm/bridge/analogix-anx7688.c     | 260 ++++++++++++++++++
 4 files changed, 340 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/anx7688.txt
 create mode 100644 drivers/gpu/drm/bridge/analogix-anx7688.c

-- 
2.24.0.393.g34dc348eaf-goog

[PATCH RESEND 1/4] dt-bindings: drm/bridge: analogix-anx7688: Add ANX7688 transmitter binding

[Hsin-Yi Wang]

From: Nicolas Boichat <drinkcat@chromium.org>

Add support for analogix,anx7688

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 .../bindings/display/bridge/anx7688.txt       | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/anx7688.txt

diff --git a/Documentation/devicetree/bindings/display/bridge/anx7688.txt b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
new file mode 100644
index 000000000000..78b55bdb18f7
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
@@ -0,0 +1,32 @@
+Analogix ANX7688 SlimPort (Single-Chip Transmitter for DP over USB-C)
+---------------------------------------------------------------------
+
+The ANX7688 is a single-chip mobile transmitter to support 4K 60 frames per
+second (4096x2160p60) or FHD 120 frames per second (1920x1080p120) video
+resolution from a smartphone or tablet with full function USB-C.
+
+This binding only describes the HDMI to DP display bridge.
+
+Required properties:
+
+ - compatible          : "analogix,anx7688"
+ - reg                 : I2C address of the device (fixed at 0x2c)
+
+Optional properties:
+
+ - Video port for HDMI input, using the DT bindings defined in [1].
+
+[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
+
+Example:
+
+	anx7688: anx7688@2c {
+		compatible = "analogix,anx7688";
+		reg = <0x2c>;
+
+		port {
+			anx7688_in: endpoint {
+				remote-endpoint = <&hdmi0_out>;
+			};
+		};
+	};
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH RESEND 1/4] dt-bindings: drm/bridge: analogix-anx7688: Add ANX7688 transmitter binding

[Laurent Pinchart]

Hi Hsin-Yi,

Thank you for the patch.

On Mon, Dec 09, 2019 at 10:50:13PM +0800, Hsin-Yi Wang wrote:
> From: Nicolas Boichat <drinkcat@chromium.org>
> 
> Add support for analogix,anx7688
> 
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
>  .../bindings/display/bridge/anx7688.txt       | 32 +++++++++++++++++++

How about converting this to yaml bindings already ? It's fairly simple
and gives you DT validation.

>  1 file changed, 32 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/anx7688.txt
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/anx7688.txt b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
> new file mode 100644
> index 000000000000..78b55bdb18f7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
> @@ -0,0 +1,32 @@
> +Analogix ANX7688 SlimPort (Single-Chip Transmitter for DP over USB-C)
> +---------------------------------------------------------------------
> +
> +The ANX7688 is a single-chip mobile transmitter to support 4K 60 frames per
> +second (4096x2160p60) or FHD 120 frames per second (1920x1080p120) video
> +resolution from a smartphone or tablet with full function USB-C.
> +
> +This binding only describes the HDMI to DP display bridge.
> +
> +Required properties:
> +
> + - compatible          : "analogix,anx7688"
> + - reg                 : I2C address of the device (fixed at 0x2c)
> +
> +Optional properties:
> +
> + - Video port for HDMI input, using the DT bindings defined in [1].
> +
> +[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
> +
> +Example:
> +
> +	anx7688: anx7688@2c {
> +		compatible = "analogix,anx7688";
> +		reg = <0x2c>;
> +
> +		port {
> +			anx7688_in: endpoint {
> +				remote-endpoint = <&hdmi0_out>;
> +			};
> +		};
> +	};
> -- 
> 2.24.0.393.g34dc348eaf-goog
> 

-- 
Regards,

Laurent Pinchart

Re: [PATCH RESEND 1/4] dt-bindings: drm/bridge: analogix-anx7688: Add ANX7688 transmitter binding

[Hsin-Yi Wang]

On Mon, Dec 9, 2019 at 10:53 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
Hi Laurent,

> How about converting this to yaml bindings already ? It's fairly simple
> and gives you DT validation.
>
Added in https://lore.kernel.org/lkml/20191211061911.238393-1-hsinyi@chromium.org/T/#m183b3822bf60101666436b0244b27275c6765d20

Thanks

[PATCH RESEND 2/4] drm: bridge: anx7688: Add anx7688 bridge driver support.

[Hsin-Yi Wang]

From: Nicolas Boichat <drinkcat@chromium.org>

ANX7688 is a HDMI to DP converter (as well as USB-C port controller),
that has an internal microcontroller.

The only reason a Linux kernel driver is necessary is to reject
resolutions that require more bandwidth than what is available on
the DP side. DP bandwidth and lane count are reported by the bridge
via 2 registers on I2C.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 drivers/gpu/drm/bridge/Kconfig            |   9 +
 drivers/gpu/drm/bridge/Makefile           |   1 +
 drivers/gpu/drm/bridge/analogix-anx7688.c | 203 ++++++++++++++++++++++
 3 files changed, 213 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/analogix-anx7688.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 34362976cd6f..1f3fc6bec842 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -16,6 +16,15 @@ config DRM_PANEL_BRIDGE
 menu "Display Interface Bridges"
 	depends on DRM && DRM_BRIDGE
 
+config DRM_ANALOGIX_ANX7688
+	tristate "Analogix ANX7688 bridge"
+	select DRM_KMS_HELPER
+	select REGMAP_I2C
+	---help---
+	  ANX7688 is a transmitter to support DisplayPort over USB-C for
+	  smartphone and tablets.
+	  This driver only supports the HDMI to DP component of the chip.
+
 config DRM_ANALOGIX_ANX78XX
 	tristate "Analogix ANX78XX bridge"
 	select DRM_KMS_HELPER
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 4934fcf5a6f8..7a1e0ec032e6 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_DRM_ANALOGIX_ANX7688) += analogix-anx7688.o
 obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
 obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
 obj-$(CONFIG_DRM_DUMB_VGA_DAC) += dumb-vga-dac.o
diff --git a/drivers/gpu/drm/bridge/analogix-anx7688.c b/drivers/gpu/drm/bridge/analogix-anx7688.c
new file mode 100644
index 000000000000..5a3a2251c1c5
--- /dev/null
+++ b/drivers/gpu/drm/bridge/analogix-anx7688.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ANX7688 HDMI->DP bridge driver
+ *
+ * Copyright 2016 Google LLC
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_crtc.h>
+
+/* Register addresses */
+#define VENDOR_ID_REG 0x00
+#define DEVICE_ID_REG 0x02
+
+#define FW_VERSION_REG 0x80
+
+#define DP_BANDWIDTH_REG 0x85
+#define DP_LANE_COUNT_REG 0x86
+
+#define VENDOR_ID 0x1f29
+#define DEVICE_ID 0x7688
+
+/* First supported firmware version (0.85) */
+#define MINIMUM_FW_VERSION 0x0085
+
+struct anx7688 {
+	struct drm_bridge bridge;
+	struct i2c_client *client;
+	struct regmap *regmap;
+
+	bool filter;
+};
+
+static inline struct anx7688 *bridge_to_anx7688(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct anx7688, bridge);
+}
+
+static bool anx7688_bridge_mode_fixup(struct drm_bridge *bridge,
+				      const struct drm_display_mode *mode,
+				      struct drm_display_mode *adjusted_mode)
+{
+	struct anx7688 *anx7688 = bridge_to_anx7688(bridge);
+	u8 regs[2];
+	u8 dpbw, lanecount;
+	int totalbw, requiredbw;
+	int ret;
+
+	if (!anx7688->filter)
+		return true;
+
+	/* Read both regs 0x85 (bandwidth) and 0x86 (lane count). */
+	ret = regmap_bulk_read(anx7688->regmap, DP_BANDWIDTH_REG, regs, 2);
+	if (ret < 0) {
+		dev_err(&anx7688->client->dev,
+			"Failed to read bandwidth/lane count\n");
+		return false;
+	}
+	dpbw = regs[0];
+	lanecount = regs[1];
+
+	/* Maximum 0x19 bandwidth (6.75 Gbps Turbo mode), 2 lanes */
+	if (dpbw > 0x19 || lanecount > 2) {
+		dev_err(&anx7688->client->dev,
+			"Invalid bandwidth/lane count (%02x/%d)\n",
+			dpbw, lanecount);
+		return false;
+	}
+
+	/* Compute available bandwidth (kHz) */
+	totalbw = dpbw * lanecount * 270000 * 8 / 10;
+
+	/* Required bandwidth (8 bpc, kHz) */
+	requiredbw = mode->clock * 8 * 3;
+
+	dev_dbg(&anx7688->client->dev,
+		"DP bandwidth: %d kHz (%02x/%d); mode requires %d Khz\n",
+		totalbw, dpbw, lanecount, requiredbw);
+
+	if (totalbw == 0) {
+		dev_warn(&anx7688->client->dev,
+			 "Bandwidth/lane count are 0, not rejecting modes\n");
+		return true;
+	}
+
+	return totalbw >= requiredbw;
+}
+
+static const struct drm_bridge_funcs anx7688_bridge_funcs = {
+	.mode_fixup	= anx7688_bridge_mode_fixup,
+};
+
+static const struct regmap_config anx7688_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int anx7688_i2c_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct anx7688 *anx7688;
+	struct device *dev = &client->dev;
+	int ret;
+	u8 buffer[4];
+	u16 vendor, device, fwversion;
+
+	anx7688 = devm_kzalloc(dev, sizeof(*anx7688), GFP_KERNEL);
+	if (!anx7688)
+		return -ENOMEM;
+
+#if IS_ENABLED(CONFIG_OF)
+	anx7688->bridge.of_node = client->dev.of_node;
+#endif
+
+	anx7688->client = client;
+	i2c_set_clientdata(client, anx7688);
+
+	anx7688->regmap =
+		devm_regmap_init_i2c(client, &anx7688_regmap_config);
+
+	/* Read both vendor and device id (4 bytes). */
+	ret = regmap_bulk_read(anx7688->regmap, VENDOR_ID_REG, buffer, 4);
+	if (ret) {
+		dev_err(dev, "Failed to read chip vendor/device id\n");
+		return ret;
+	}
+
+	vendor = (u16)buffer[1] << 8 | buffer[0];
+	device = (u16)buffer[3] << 8 | buffer[2];
+	if (vendor != VENDOR_ID || device != DEVICE_ID) {
+		dev_err(dev, "Invalid vendor/device id %04x/%04x\n",
+			vendor, device);
+		return -ENODEV;
+	}
+
+	ret = regmap_bulk_read(anx7688->regmap, FW_VERSION_REG, buffer, 2);
+	if (ret) {
+		dev_err(&client->dev, "Failed to read firmware version\n");
+		return ret;
+	}
+
+	fwversion = (u16)buffer[0] << 8 | buffer[1];
+	dev_info(dev, "ANX7688 firwmare version %02x.%02x\n",
+		 buffer[0], buffer[1]);
+
+	/* FW version >= 0.85 supports bandwidth/lane count registers */
+	if (fwversion >= MINIMUM_FW_VERSION) {
+		anx7688->filter = true;
+	} else {
+		/* Warn, but not fail, for backwards compatibility. */
+		dev_warn(dev,
+			 "Old ANX7688 FW version (%02x.%02x), not filtering\n",
+			 buffer[0], buffer[1]);
+	}
+
+	anx7688->bridge.funcs = &anx7688_bridge_funcs;
+	drm_bridge_add(&anx7688->bridge);
+
+	return 0;
+}
+
+static int anx7688_i2c_remove(struct i2c_client *client)
+{
+	struct anx7688 *anx7688 = i2c_get_clientdata(client);
+
+	drm_bridge_remove(&anx7688->bridge);
+
+	return 0;
+}
+
+static const struct i2c_device_id anx7688_id[] = {
+	{ "anx7688", 0 },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(i2c, anx7688_id);
+
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id anx7688_match_table[] = {
+	{ .compatible = "analogix,anx7688", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, anx7688_match_table);
+#endif
+
+static struct i2c_driver anx7688_driver = {
+	.driver = {
+		   .name = "anx7688",
+		   .of_match_table = of_match_ptr(anx7688_match_table),
+		  },
+	.probe = anx7688_i2c_probe,
+	.remove = anx7688_i2c_remove,
+	.id_table = anx7688_id,
+};
+
+module_i2c_driver(anx7688_driver);
+
+MODULE_DESCRIPTION("ANX7688 SlimPort Transmitter driver");
+MODULE_AUTHOR("Nicolas Boichat <drinkcat@chromium.org>");
+MODULE_LICENSE("GPL v2");
-- 
2.24.0.393.g34dc348eaf-goog

[PATCH RESEND 3/4] dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO

[Hsin-Yi Wang]

Support optional feature: bypass GPIO.

Some SoC (eg. mt8173) have a hardware mux that connects to 2 ports:
anx7688 and hdmi. When the GPIO is active, the bridge is bypassed.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 .../bindings/display/bridge/anx7688.txt       | 40 ++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/anx7688.txt b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
index 78b55bdb18f7..44185dcac839 100644
--- a/Documentation/devicetree/bindings/display/bridge/anx7688.txt
+++ b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
@@ -15,10 +15,13 @@ Required properties:
 Optional properties:
 
  - Video port for HDMI input, using the DT bindings defined in [1].
+ - bypass-gpios        : External GPIO. If this GPIO is active, we assume
+ the bridge is bypassed (e.g. by a mux).
+ - pinctrl-0, pinctrl-names: the pincontrol settings to configure bypass GPIO.
 
 [1]: Documentation/devicetree/bindings/media/video-interfaces.txt
 
-Example:
+Example 1:
 
 	anx7688: anx7688@2c {
 		compatible = "analogix,anx7688";
@@ -30,3 +33,38 @@ Example:
 			};
 		};
 	};
+
+Example 2:
+
+       anx7688: anx7688@2c {
+               compatible = "analogix,anx7688";
+               status = "okay";
+               reg = <0x2c>;
+               ddc-i2c-bus = <&hdmiddc0>;
+
+               bypass-gpios = <&pio 36 GPIO_ACTIVE_HIGH>;
+               pinctrl-names = "default";
+               pinctrl-0 = <&hdmi_mux_pins>;
+
+               ports {
+                       #address-cells = <1>;
+                       #size-cells = <0>;
+
+                       port@0 { /* input */
+                               reg = <0>;
+
+                               anx7688_in: endpoint {
+                                       remote-endpoint = <&hdmi_out_anx>;
+                               };
+                       };
+
+                       port@1 { /* output */
+                               reg = <1>;
+
+                               anx7688_out: endpoint {
+                                       remote-endpoint = <&hdmi_connector_in>;
+                               };
+                       };
+               };
+       };
+
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH RESEND 3/4] dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO

[Laurent Pinchart]

Hi Hsin-Yi,

Thank you for the patch.

On Mon, Dec 09, 2019 at 10:50:15PM +0800, Hsin-Yi Wang wrote:
> Support optional feature: bypass GPIO.
> 
> Some SoC (eg. mt8173) have a hardware mux that connects to 2 ports:
> anx7688 and hdmi. When the GPIO is active, the bridge is bypassed.

This doesn't look like the right place to fix this, as the mux is
unrelated to the bridge. You would have to duplicate this logic in every
bridge driver otherwise.

Could you describe the hardware topology in a bit more details ? I can
then try to advise on how to best support it.

> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
>  .../bindings/display/bridge/anx7688.txt       | 40 ++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/anx7688.txt b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
> index 78b55bdb18f7..44185dcac839 100644
> --- a/Documentation/devicetree/bindings/display/bridge/anx7688.txt
> +++ b/Documentation/devicetree/bindings/display/bridge/anx7688.txt
> @@ -15,10 +15,13 @@ Required properties:
>  Optional properties:
>  
>   - Video port for HDMI input, using the DT bindings defined in [1].
> + - bypass-gpios        : External GPIO. If this GPIO is active, we assume
> + the bridge is bypassed (e.g. by a mux).
> + - pinctrl-0, pinctrl-names: the pincontrol settings to configure bypass GPIO.
>  
>  [1]: Documentation/devicetree/bindings/media/video-interfaces.txt
>  
> -Example:
> +Example 1:
>  
>  	anx7688: anx7688@2c {
>  		compatible = "analogix,anx7688";
> @@ -30,3 +33,38 @@ Example:
>  			};
>  		};
>  	};
> +
> +Example 2:
> +
> +       anx7688: anx7688@2c {
> +               compatible = "analogix,anx7688";
> +               status = "okay";
> +               reg = <0x2c>;
> +               ddc-i2c-bus = <&hdmiddc0>;
> +
> +               bypass-gpios = <&pio 36 GPIO_ACTIVE_HIGH>;
> +               pinctrl-names = "default";
> +               pinctrl-0 = <&hdmi_mux_pins>;
> +
> +               ports {
> +                       #address-cells = <1>;
> +                       #size-cells = <0>;
> +
> +                       port@0 { /* input */
> +                               reg = <0>;
> +
> +                               anx7688_in: endpoint {
> +                                       remote-endpoint = <&hdmi_out_anx>;
> +                               };
> +                       };
> +
> +                       port@1 { /* output */
> +                               reg = <1>;
> +
> +                               anx7688_out: endpoint {
> +                                       remote-endpoint = <&hdmi_connector_in>;
> +                               };
> +                       };
> +               };
> +       };
> +

-- 
Regards,

Laurent Pinchart

Re: [PATCH RESEND 3/4] dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO

[Hsin-Yi Wang]

On Mon, Dec 9, 2019 at 10:55 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Hsin-Yi,
>
> Thank you for the patch.
>
> On Mon, Dec 09, 2019 at 10:50:15PM +0800, Hsin-Yi Wang wrote:
> > Support optional feature: bypass GPIO.
> >
> > Some SoC (eg. mt8173) have a hardware mux that connects to 2 ports:
> > anx7688 and hdmi. When the GPIO is active, the bridge is bypassed.
>
> This doesn't look like the right place to fix this, as the mux is
> unrelated to the bridge. You would have to duplicate this logic in every
> bridge driver otherwise.
>
> Could you describe the hardware topology in a bit more details ? I can
> then try to advise on how to best support it.
>
Hi Laurent,

The mt8173 layout is:

MT8173 HDMI bridge-- hardware mux --- HDMI
                                                   |
                                                    ------------ anx7688
There's a hardware mux that takes mt8173 hdmi as input and has 2
output port: native hdmi and anx7688 bridge.
If gpio is active, we would like it to go to HDMI.

Previous approach is to make hardware mux a generic gpio mux bridge,
but this is probably a very rare use case that is only for
mt8173.(https://lore.kernel.org/lkml/57723AD2.8020806@codeaurora.org/)
We merge the mux and anx7688 to a single bridge and leave this as an
optional feature in this time.

Thanks.

Re: [PATCH RESEND 3/4] dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO

[Laurent Pinchart]

Hi Hsin-Yi,

On Mon, Dec 09, 2019 at 11:09:34PM +0800, Hsin-Yi Wang wrote:
> On Mon, Dec 9, 2019 at 10:55 PM Laurent Pinchart wrote:
> > On Mon, Dec 09, 2019 at 10:50:15PM +0800, Hsin-Yi Wang wrote:
> > > Support optional feature: bypass GPIO.
> > >
> > > Some SoC (eg. mt8173) have a hardware mux that connects to 2 ports:
> > > anx7688 and hdmi. When the GPIO is active, the bridge is bypassed.
> >
> > This doesn't look like the right place to fix this, as the mux is
> > unrelated to the bridge. You would have to duplicate this logic in every
> > bridge driver otherwise.
> >
> > Could you describe the hardware topology in a bit more details ? I can
> > then try to advise on how to best support it.
>
> Hi Laurent,
> 
> The mt8173 layout is:
> 
> MT8173 HDMI bridge-- hardware mux --- HDMI
>                                                    |
>                                                     ------------ anx7688

You may have used a proportional font when writing this, the | doesn't
align with anything using a fixed font. Do I assume correctly that the
hardware multiplexer is actually a demultiplexer with one input and two
outputs ?
                                     +-----------+
+---------+         +------+    /--> | HDMI      |
| MT8173  |  HDMI   |   -->| --/     | Connector |
|  HDMI   | ------> |--/   |         +-----------+
| Encoder |         |    ->| --\     +-----------+      +-----------+
+---------+         +------+    \--> | ANX7688   | ---> | USB-C     |
                                     | Bridge    |      | Connector |
				     +-----------+      +-----------+

> There's a hardware mux that takes mt8173 hdmi as input and has 2
> output port: native hdmi and anx7688 bridge.
> If gpio is active, we would like it to go to HDMI.
> 
> Previous approach is to make hardware mux a generic gpio mux bridge,
> but this is probably a very rare use case that is only for
> mt8173.(https://lore.kernel.org/lkml/57723AD2.8020806@codeaurora.org/)
> We merge the mux and anx7688 to a single bridge and leave this as an
> optional feature in this time.

I think that's a better approach, at least at the DT level. The HDMI
demultiplexer should be represented as a DT node with 3 ports (one input
and two outputs) with a control GPIO.

From a video point of view, the ANX7688 should be represented as a DT
node with 2 ports (one input and one output), regardless of whether it
is used in conjunction with an HDMI switch as shown above, or directly
connected to the output of an HDMI encoder. However, as the ANX7688
supports both DP output and USB-C output, the situation may be slightly
more complex. Please see https://patchwork.kernel.org/patch/11184895/
for a similar discussion, related to the ANX7625.

In any case, I don't think the ANX7688 should care about the GPIO.

-- 
Regards,

Laurent Pinchart

Re: [PATCH RESEND 3/4] dt-bindings: drm/bridge: analogix-anx78xx: support bypass GPIO

[Hsin-Yi Wang]

On Mon, Dec 9, 2019 at 11:32 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
Hi Laurent,
> You may have used a proportional font when writing this, the | doesn't
> align with anything using a fixed font. Do I assume correctly that the
> hardware multiplexer is actually a demultiplexer with one input and two
> outputs ?
>                                      +-----------+
> +---------+         +------+    /--> | HDMI      |
> | MT8173  |  HDMI   |   -->| --/     | Connector |
> |  HDMI   | ------> |--/   |         +-----------+
> | Encoder |         |    ->| --\     +-----------+      +-----------+
> +---------+         +------+    \--> | ANX7688   | ---> | USB-C     |
>                                      | Bridge    |      | Connector |
>                                      +-----------+      +-----------+
>
Sorry for not noticing the font issue, this graph is correct.

> > There's a hardware mux that takes mt8173 hdmi as input and has 2
> > output port: native hdmi and anx7688 bridge.
> > If gpio is active, we would like it to go to HDMI.
> >
> > Previous approach is to make hardware mux a generic gpio mux bridge,
> > but this is probably a very rare use case that is only for
> > mt8173.(https://lore.kernel.org/lkml/57723AD2.8020806@codeaurora.org/)
> > We merge the mux and anx7688 to a single bridge and leave this as an
> > optional feature in this time.
>
> I think that's a better approach, at least at the DT level. The HDMI
> demultiplexer should be represented as a DT node with 3 ports (one input
> and two outputs) with a control GPIO.
>
I've resend the original gpio mux driver. So for anx7688 there's 1
input and 1 output.

Thanks

[PATCH RESEND 4/4] drm: bridge: anx7688: Support bypass GPIO feature

[Hsin-Yi Wang]

Support optional feature: bypass GPIO.

Get GPIO status in irq handler. If GPIO is active, mode_fixup would be
bypassed.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
 drivers/gpu/drm/bridge/analogix-anx7688.c | 57 +++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix-anx7688.c b/drivers/gpu/drm/bridge/analogix-anx7688.c
index 5a3a2251c1c5..1d09db2cf8e9 100644
--- a/drivers/gpu/drm/bridge/analogix-anx7688.c
+++ b/drivers/gpu/drm/bridge/analogix-anx7688.c
@@ -5,11 +5,16 @@
  * Copyright 2016 Google LLC
  */
 
+#include <linux/gpio.h>
 #include <linux/i2c.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/of_gpio.h>
 #include <linux/regmap.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_probe_helper.h>
 
 /* Register addresses */
 #define VENDOR_ID_REG 0x00
@@ -31,6 +36,9 @@ struct anx7688 {
 	struct i2c_client *client;
 	struct regmap *regmap;
 
+	struct gpio_desc *gpiod_bypass;
+	int bypass;
+
 	bool filter;
 };
 
@@ -49,6 +57,10 @@ static bool anx7688_bridge_mode_fixup(struct drm_bridge *bridge,
 	int totalbw, requiredbw;
 	int ret;
 
+	/* bypass anx mode fixup */
+	if (anx7688->bypass)
+		return true;
+
 	if (!anx7688->filter)
 		return true;
 
@@ -93,6 +105,19 @@ static const struct drm_bridge_funcs anx7688_bridge_funcs = {
 	.mode_fixup	= anx7688_bridge_mode_fixup,
 };
 
+static irqreturn_t gpio_display_mux_det_threaded_handler(int unused, void *data)
+{
+	struct anx7688 *anx7688 = data;
+
+	anx7688->bypass = gpiod_get_value(anx7688->gpiod_bypass);
+	dev_dbg(&anx7688->client->dev, "Interrupt %d!\n", anx7688->bypass);
+
+	if (anx7688->bridge.dev)
+		drm_kms_helper_hotplug_event(anx7688->bridge.dev);
+
+	return IRQ_HANDLED;
+}
+
 static const struct regmap_config anx7688_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
@@ -156,6 +181,38 @@ static int anx7688_i2c_probe(struct i2c_client *client,
 			 buffer[0], buffer[1]);
 	}
 
+	/* Optional bypass-gpios */
+	anx7688->gpiod_bypass = devm_gpiod_get_optional(dev, "bypass",
+							GPIOD_IN);
+	if (IS_ERR(anx7688->gpiod_bypass)) {
+		ret = PTR_ERR(anx7688->gpiod_bypass);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "bypass-gpios assigned failed\n");
+		return ret;
+	}
+	if (anx7688->gpiod_bypass) {
+		int irq;
+
+		irq = gpiod_to_irq(anx7688->gpiod_bypass);
+		if (irq < 0) {
+			dev_err(dev, "Failed to get output irq %d\n", irq);
+			return -ENODEV;
+		}
+
+		anx7688->bypass = gpiod_get_value(anx7688->gpiod_bypass);
+
+		ret = devm_request_threaded_irq(dev, irq, NULL,
+				gpio_display_mux_det_threaded_handler,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
+				IRQF_ONESHOT,
+				"gpio-display-mux-det", anx7688);
+		if (ret) {
+			dev_err(dev,
+				"Failed to request MUX_DET threaded irq\n");
+			return ret;
+		}
+	}
+
 	anx7688->bridge.funcs = &anx7688_bridge_funcs;
 	drm_bridge_add(&anx7688->bridge);
 
-- 
2.24.0.393.g34dc348eaf-goog