diff mbox series

[v4,15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers

Message ID 20210416153909.v4.15.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid (mailing list archive)
State Superseded
Headers show
Series drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems | expand

Commit Message

Doug Anderson April 16, 2021, 10:39 p.m. UTC
Let's use the newly minted aux bus to break up the driver into sub
drivers. We're not doing a full breakup here: all the code is still in
the same file and remains largely untouched. The big goal here of
using sub-drivers is to allow part of our code to finish probing even
if some other code needs to defer. This can solve some chicken-and-egg
problems. Specifically:
- In commit 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for
  delaying prepare()") we had to add a bit of a hack to simpel-panel
  to support HPD showing up late. We can get rid of that hack now
  since the GPIO part of our driver can finish probing early.
- We have a desire to expose our DDC bus to simple-panel (and perhaps
  to a backlight driver?). That will end up with the same
  chicken-and-egg problem. A future patch to move this to a sub-driver
  will fix it.
- If/when we support the PWM functionality present in the bridge chip
  for a backlight we'll end up with another chicken-and-egg
  problem. If we allow the PWM to be a sub-driver too then it solves
  this problem.

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

(no changes since v1)

 drivers/gpu/drm/bridge/Kconfig        |   1 +
 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 211 +++++++++++++++++++-------
 2 files changed, 158 insertions(+), 54 deletions(-)

Comments

Bjorn Andersson April 23, 2021, 2:49 p.m. UTC | #1
On Fri 16 Apr 17:39 CDT 2021, Douglas Anderson wrote:

> Let's use the newly minted aux bus to break up the driver into sub
> drivers. We're not doing a full breakup here: all the code is still in
> the same file and remains largely untouched. The big goal here of
> using sub-drivers is to allow part of our code to finish probing even
> if some other code needs to defer. This can solve some chicken-and-egg
> problems. Specifically:
> - In commit 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for
>   delaying prepare()") we had to add a bit of a hack to simpel-panel
>   to support HPD showing up late. We can get rid of that hack now
>   since the GPIO part of our driver can finish probing early.
> - We have a desire to expose our DDC bus to simple-panel (and perhaps
>   to a backlight driver?). That will end up with the same
>   chicken-and-egg problem. A future patch to move this to a sub-driver
>   will fix it.
> - If/when we support the PWM functionality present in the bridge chip
>   for a backlight we'll end up with another chicken-and-egg
>   problem. If we allow the PWM to be a sub-driver too then it solves
>   this problem.

I rebased my pwm_chip patch ontop of this and it works like a charm!

> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
> (no changes since v1)
> 
>  drivers/gpu/drm/bridge/Kconfig        |   1 +
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 211 +++++++++++++++++++-------
>  2 files changed, 158 insertions(+), 54 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 22a467abd3e9..6868050961a2 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -267,6 +267,7 @@ config DRM_TI_SN65DSI86
>  	select REGMAP_I2C
>  	select DRM_PANEL
>  	select DRM_MIPI_DSI
> +	select AUXILIARY_BUS
>  	help
>  	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
>  
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 57bc489a0412..44edcf6f5744 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -4,6 +4,7 @@
>   * datasheet: https://www.ti.com/lit/ds/symlink/sn65dsi86.pdf
>   */
>  
> +#include <linux/auxiliary_bus.h>
>  #include <linux/bits.h>
>  #include <linux/clk.h>
>  #include <linux/debugfs.h>
> @@ -113,7 +114,10 @@
>  
>  /**
>   * struct ti_sn65dsi86 - Platform data for ti-sn65dsi86 driver.
> - * @dev:          Pointer to our device.
> + * @bridge_aux:   AUX-bus sub device for MIPI-to-eDP bridge functionality.
> + * @gpio_aux:     AUX-bus sub device for GPIO controller functionality.
> + *
> + * @dev:          Pointer to the top level (i2c) device.
>   * @regmap:       Regmap for accessing i2c.
>   * @aux:          Our aux channel.
>   * @bridge:       Our bridge.
> @@ -140,6 +144,9 @@
>   *                each other's read-modify-write.
>   */
>  struct ti_sn65dsi86 {
> +	struct auxiliary_device		bridge_aux;
> +	struct auxiliary_device		gpio_aux;
> +
>  	struct device			*dev;
>  	struct regmap			*regmap;
>  	struct drm_dp_aux		aux;
> @@ -1135,8 +1142,10 @@ static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = {
>  	"GPIO1", "GPIO2", "GPIO3", "GPIO4"
>  };
>  
> -static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
> +static int ti_sn_gpio_probe(struct auxiliary_device *adev,
> +			    const struct auxiliary_device_id *id)
>  {
> +	struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
>  	int ret;
>  
>  	/* Only init if someone is going to use us as a GPIO controller */
> @@ -1158,19 +1167,27 @@ static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
>  	pdata->gchip.names = ti_sn_bridge_gpio_names;
>  	pdata->gchip.ngpio = SN_NUM_GPIOS;
>  	pdata->gchip.base = -1;
> -	ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
> +	ret = devm_gpiochip_add_data(&adev->dev, &pdata->gchip, pdata);
>  	if (ret)
>  		dev_err(pdata->dev, "can't add gpio chip\n");
>  
>  	return ret;
>  }
>  
> -#else
> +static const struct auxiliary_device_id ti_sn_gpio_id_table[] = {
> +	{ .name = "ti_sn65dsi86.gpio", },
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(auxiliary, ti_sn_gpio_id_table);

The MODULE_DEVICE_TABLE will ensure that the driver will be autoloaded
if this auxiliary compatible is requested, but it's only ever going to
be triggered by the already loaded driver.

So you can omit this.

>  
> -static inline int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
> -{
> -	return 0;
> -}
> +static struct auxiliary_driver ti_sn_gpio_driver = {
> +	.name = "gpio",
> +	.probe = ti_sn_gpio_probe,
> +	.id_table = ti_sn_gpio_id_table,
> +};
> +
> +module_auxiliary_driver(ti_sn_gpio_driver);

You may only have a single module_driver() per driver. Compiling the
driver as a module will result in a spew of errors because init_module()
and cleanup_module() are defined multiple times.

As such I believe you have to roll your own init/exit. I did the
following for my testing:

====8<-----------------

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 62904dfdee0a..fe3317bc85be 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -1218,8 +1218,6 @@ static struct auxiliary_driver ti_sn_gpio_driver = {
 	.id_table = ti_sn_gpio_id_table,
 };
 
-module_auxiliary_driver(ti_sn_gpio_driver);
-
 #endif
 
 static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
@@ -1329,8 +1327,6 @@ static struct auxiliary_driver ti_sn_bridge_driver = {
 	.id_table = ti_sn_bridge_id_table,
 };
 
-module_auxiliary_driver(ti_sn_bridge_driver);
-
 static void ti_sn65dsi86_runtime_disable(void *data)
 {
 	pm_runtime_disable(data);
@@ -1432,8 +1428,6 @@ static struct auxiliary_driver ti_sn_aux_driver = {
 	.id_table = ti_sn_aux_id_table,
 };
 
-module_auxiliary_driver(ti_sn_aux_driver);
-
 static int ti_sn65dsi86_probe(struct i2c_client *client,
 			      const struct i2c_device_id *id)
 {
@@ -1535,7 +1529,32 @@ static struct i2c_driver ti_sn65dsi86_driver = {
 	.probe = ti_sn65dsi86_probe,
 	.id_table = ti_sn65dsi86_id,
 };
-module_i2c_driver(ti_sn65dsi86_driver);
+
+static int ti_sn65dsi86_init(void)
+{
+#if defined(CONFIG_OF_GPIO)
+	auxiliary_driver_register(&ti_sn_gpio_driver);
+#endif
+	auxiliary_driver_register(&ti_sn_bridge_driver);
+	auxiliary_driver_register(&ti_sn_aux_driver);
+
+	i2c_add_driver(&ti_sn65dsi86_driver);
+
+	return 0;
+}
+module_init(ti_sn65dsi86_init);
+
+static void ti_sn65dsi86_exit(void)
+{
+	i2c_del_driver(&ti_sn65dsi86_driver);
+
+#if defined(CONFIG_OF_GPIO)
+	auxiliary_driver_unregister(&ti_sn_gpio_driver);
+#endif
+	auxiliary_driver_unregister(&ti_sn_bridge_driver);
+	auxiliary_driver_unregister(&ti_sn_aux_driver);
+}
+module_exit(ti_sn65dsi86_exit);
 
 MODULE_AUTHOR("Sandeep Panda <spanda@codeaurora.org>");
 MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");

8<-----------------

The rest looks good!

Regards,
Bjorn
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 22a467abd3e9..6868050961a2 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -267,6 +267,7 @@  config DRM_TI_SN65DSI86
 	select REGMAP_I2C
 	select DRM_PANEL
 	select DRM_MIPI_DSI
+	select AUXILIARY_BUS
 	help
 	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
 
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 57bc489a0412..44edcf6f5744 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -4,6 +4,7 @@ 
  * datasheet: https://www.ti.com/lit/ds/symlink/sn65dsi86.pdf
  */
 
+#include <linux/auxiliary_bus.h>
 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/debugfs.h>
@@ -113,7 +114,10 @@ 
 
 /**
  * struct ti_sn65dsi86 - Platform data for ti-sn65dsi86 driver.
- * @dev:          Pointer to our device.
+ * @bridge_aux:   AUX-bus sub device for MIPI-to-eDP bridge functionality.
+ * @gpio_aux:     AUX-bus sub device for GPIO controller functionality.
+ *
+ * @dev:          Pointer to the top level (i2c) device.
  * @regmap:       Regmap for accessing i2c.
  * @aux:          Our aux channel.
  * @bridge:       Our bridge.
@@ -140,6 +144,9 @@ 
  *                each other's read-modify-write.
  */
 struct ti_sn65dsi86 {
+	struct auxiliary_device		bridge_aux;
+	struct auxiliary_device		gpio_aux;
+
 	struct device			*dev;
 	struct regmap			*regmap;
 	struct drm_dp_aux		aux;
@@ -1135,8 +1142,10 @@  static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = {
 	"GPIO1", "GPIO2", "GPIO3", "GPIO4"
 };
 
-static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
+static int ti_sn_gpio_probe(struct auxiliary_device *adev,
+			    const struct auxiliary_device_id *id)
 {
+	struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
 	int ret;
 
 	/* Only init if someone is going to use us as a GPIO controller */
@@ -1158,19 +1167,27 @@  static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
 	pdata->gchip.names = ti_sn_bridge_gpio_names;
 	pdata->gchip.ngpio = SN_NUM_GPIOS;
 	pdata->gchip.base = -1;
-	ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
+	ret = devm_gpiochip_add_data(&adev->dev, &pdata->gchip, pdata);
 	if (ret)
 		dev_err(pdata->dev, "can't add gpio chip\n");
 
 	return ret;
 }
 
-#else
+static const struct auxiliary_device_id ti_sn_gpio_id_table[] = {
+	{ .name = "ti_sn65dsi86.gpio", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(auxiliary, ti_sn_gpio_id_table);
 
-static inline int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
-{
-	return 0;
-}
+static struct auxiliary_driver ti_sn_gpio_driver = {
+	.name = "gpio",
+	.probe = ti_sn_gpio_probe,
+	.id_table = ti_sn_gpio_id_table,
+};
+
+module_auxiliary_driver(ti_sn_gpio_driver);
 
 #endif
 
@@ -1223,11 +1240,128 @@  static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
 	pdata->ln_polrs = ln_polrs;
 }
 
+static int ti_sn_bridge_probe(struct auxiliary_device *adev,
+			      const struct auxiliary_device_id *id)
+{
+	struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+	struct device_node *np = pdata->dev->of_node;
+	int ret;
+
+	ret = drm_of_find_panel_or_bridge(np, 1, 0, &pdata->panel, NULL);
+	if (ret) {
+		DRM_ERROR("could not find any panel node\n");
+		return ret;
+	}
+
+	ti_sn_bridge_parse_lanes(pdata, np);
+
+	ret = ti_sn_bridge_parse_dsi_host(pdata);
+	if (ret)
+		return ret;
+
+	pdata->aux.name = "ti-sn65dsi86-aux";
+	pdata->aux.dev = pdata->dev;
+	pdata->aux.transfer = ti_sn_aux_transfer;
+	drm_dp_aux_init(&pdata->aux);
+
+	pdata->bridge.funcs = &ti_sn_bridge_funcs;
+	pdata->bridge.of_node = np;
+
+	drm_bridge_add(&pdata->bridge);
+
+	return 0;
+}
+
+static void ti_sn_bridge_remove(struct auxiliary_device *adev)
+{
+	struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+
+	if (!pdata)
+		return;
+
+	if (pdata->dsi) {
+		mipi_dsi_detach(pdata->dsi);
+		mipi_dsi_device_unregister(pdata->dsi);
+	}
+
+	kfree(pdata->edid);
+
+	drm_bridge_remove(&pdata->bridge);
+
+	of_node_put(pdata->host_node);
+}
+
+static const struct auxiliary_device_id ti_sn_bridge_id_table[] = {
+	{ .name = "ti_sn65dsi86.bridge", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(auxiliary, ti_sn_bridge_id_table);
+
+static struct auxiliary_driver ti_sn_bridge_driver = {
+	.name = "bridge",
+	.probe = ti_sn_bridge_probe,
+	.remove = ti_sn_bridge_remove,
+	.id_table = ti_sn_bridge_id_table,
+};
+
+module_auxiliary_driver(ti_sn_bridge_driver);
+
 static void ti_sn65dsi86_runtime_disable(void *data)
 {
 	pm_runtime_disable(data);
 }
 
+static void ti_sn65dsi86_uninit_aux(void *data)
+{
+	auxiliary_device_uninit(data);
+}
+
+static void ti_sn65dsi86_delete_aux(void *data)
+{
+	auxiliary_device_delete(data);
+}
+
+/*
+ * AUX bus docs say that a non-NULL release is mandatory, but it makes no
+ * sense for the model used here where all of the aux devices are allocated
+ * in the single shared structure. We'll use this noop as a workaround.
+ */
+static void ti_sn65dsi86_noop(struct device *dev) {}
+
+static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
+				       struct auxiliary_device *aux,
+				       const char *name)
+{
+	struct device *dev = pdata->dev;
+	int ret;
+
+	/*
+	 * NOTE: It would be nice to set the "of_node" of our children to be
+	 * the same "of_node"" that the top-level component has. That doesn't
+	 * work, though, since pinctrl will try (and fail) to reserve the
+	 * pins again. Until that gets sorted out the children will just need
+	 * to look at the of_node of the main device.
+	 */
+
+	aux->name = name;
+	aux->dev.parent = dev;
+	aux->dev.release = ti_sn65dsi86_noop;
+	ret = auxiliary_device_init(aux);
+	if (ret)
+		return ret;
+	ret = devm_add_action_or_reset(dev, ti_sn65dsi86_uninit_aux, aux);
+	if (ret)
+		return ret;
+
+	ret = auxiliary_device_add(aux);
+	if (ret)
+		return ret;
+	ret = devm_add_action_or_reset(dev, ti_sn65dsi86_delete_aux, aux);
+
+	return ret;
+}
+
 static int ti_sn65dsi86_probe(struct i2c_client *client,
 			      const struct i2c_device_id *id)
 {
@@ -1277,54 +1411,24 @@  static int ti_sn65dsi86_probe(struct i2c_client *client,
 
 	ti_sn65dsi86_debugfs_init(pdata);
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &pdata->panel, NULL);
-	if (ret) {
-		DRM_ERROR("could not find any panel node\n");
-		return ret;
-	}
-
-	ti_sn_bridge_parse_lanes(pdata, dev->of_node);
-
-	ret = ti_sn_bridge_parse_dsi_host(pdata);
-	if (ret)
-		return ret;
-
-	ret = ti_sn_setup_gpio_controller(pdata);
-	if (ret)
-		return ret;
-
-	pdata->aux.name = "ti-sn65dsi86-aux";
-	pdata->aux.dev = dev;
-	pdata->aux.transfer = ti_sn_aux_transfer;
-	drm_dp_aux_init(&pdata->aux);
-
-	pdata->bridge.funcs = &ti_sn_bridge_funcs;
-	pdata->bridge.of_node = dev->of_node;
-
-	drm_bridge_add(&pdata->bridge);
-
-	return 0;
-}
-
-static int ti_sn65dsi86_remove(struct i2c_client *client)
-{
-	struct ti_sn65dsi86 *pdata = i2c_get_clientdata(client);
-
-	if (!pdata)
-		return -EINVAL;
+	/*
+	 * Break ourselves up into a collection of aux devices. The only real
+	 * motiviation here is to solve the chicken-and-egg problem of probe
+	 * ordering. The bridge wants the panel to be there when it probes.
+	 * The panel wants its HPD GPIO (provided by sn65dsi86 on some boards)
+	 * when it probes. There will soon be other devices (DDC I2C bus, PWM)
+	 * that have the same problem. Having sub-devices allows the some sub
+	 * devices to finish probing even if others return -EPROBE_DEFER and
+	 * gets us around the problems.
+	 */
 
-	if (pdata->dsi) {
-		mipi_dsi_detach(pdata->dsi);
-		mipi_dsi_device_unregister(pdata->dsi);
+	if (IS_ENABLED(CONFIG_OF_GPIO)) {
+		ret = ti_sn65dsi86_add_aux_device(pdata, &pdata->gpio_aux, "gpio");
+		if (ret)
+			return ret;
 	}
 
-	kfree(pdata->edid);
-
-	drm_bridge_remove(&pdata->bridge);
-
-	of_node_put(pdata->host_node);
-
-	return 0;
+	return ti_sn65dsi86_add_aux_device(pdata, &pdata->bridge_aux, "bridge");
 }
 
 static struct i2c_device_id ti_sn65dsi86_id[] = {
@@ -1346,7 +1450,6 @@  static struct i2c_driver ti_sn65dsi86_driver = {
 		.pm = &ti_sn65dsi86_pm_ops,
 	},
 	.probe = ti_sn65dsi86_probe,
-	.remove = ti_sn65dsi86_remove,
 	.id_table = ti_sn65dsi86_id,
 };
 module_i2c_driver(ti_sn65dsi86_driver);