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From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Sam Ravnborg <sam@ravnborg.org>, Wolfram Sang <wsa@kernel.org>,
	Stephen Boyd <swboyd@chromium.org>,
	robdclark@chromium.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>,
	Steev Klimaszewski <steev@kali.org>,
	linux-arm-msm@vger.kernel.org, Linus W <linus.walleij@linaro.org>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Robert Foss <robert.foss@linaro.org>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers
Date: Fri, 23 Apr 2021 09:49:30 -0500
Message-ID: <YILeemCMbU9FXLx4@builder.lan> (raw)
In-Reply-To: <20210416153909.v4.15.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid>

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

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 22:39 [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 01/27] drm/bridge: Fix the stop condition of drm_bridge_chain_pre_enable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 02/27] drm/bridge: ti-sn65dsi86: Simplify refclk handling Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 03/27] drm/bridge: ti-sn65dsi86: Remove incorrectly tagged kerneldoc comment Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 04/27] drm/bridge: ti-sn65dsi86: Reorder remove() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 05/27] drm/bridge: ti-sn65dsi86: Move drm_panel_unprepare() to post_disable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 06/27] drm/bridge: ti-sn65dsi86: Get rid of the useless detect() function Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 07/27] drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 08/27] drm/bridge: ti-sn65dsi86: Rename the main driver data structure Douglas Anderson
2021-04-23 14:28   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 09/27] drm/bridge: ti-sn65dsi86: More renames in prep for sub-devices Douglas Anderson
2021-04-23 14:30   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 10/27] drm/bridge: ti-sn65dsi86: Clean debugfs code Douglas Anderson
2021-04-23 14:35   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 11/27] drm/bridge: ti-sn65dsi86: Add local var for "dev" to simplify probe Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 12/27] drm/bridge: ti-sn65dsi86: Cleanup managing of drvdata Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 13/27] drm/bridge: ti-sn65dsi86: Use devm to do our runtime_disable Douglas Anderson
2021-04-23 14:39   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 14/27] drm/bridge: ti-sn65dsi86: Move all the chip-related init to the start Douglas Anderson
2021-04-23 14:41   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers Douglas Anderson
2021-04-23 14:49   ` Bjorn Andersson [this message]
2021-04-16 22:39 ` [PATCH v4 16/27] drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code Douglas Anderson
2021-04-23 14:50   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 17/27] drm/bridge: ti-sn65dsi86: Use pm_runtime autosuspend Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 18/27] drm/bridge: ti-sn65dsi86: Code motion of refclk management functions Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 19/27] drm/bridge: ti-sn65dsi86: If refclk, DP AUX can happen w/out pre-enable Douglas Anderson
2021-04-23 14:56   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 20/27] drm/bridge: ti-sn65dsi86: Promote the AUX channel to its own sub-dev Douglas Anderson
2021-04-23 14:59   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 21/27] i2c: i2c-core-of: Fix corner case of finding adapter by node Douglas Anderson
2021-04-23 15:12   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 22/27] drm/panel: panel-simple: Remove extra call: drm_connector_update_edid_property() Douglas Anderson
2021-04-23 15:15   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 23/27] drm/panel: panel-simple: Power the panel when reading the EDID Douglas Anderson
2021-04-23 15:16   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 24/27] drm/panel: panel-simple: Cache the EDID as long as we retain power Douglas Anderson
2021-04-23 16:12   ` Bjorn Andersson
2021-04-23 16:30     ` Doug Anderson
2021-04-16 22:39 ` [PATCH v4 25/27] drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC Douglas Anderson
2021-04-23 16:13   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 26/27] arm64: dts: qcom: Link the panel to the bridge's DDC bus Douglas Anderson
2021-04-23 16:16   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 27/27] drm/panel: panel-simple: Prepare/unprepare are refcounted, not forced Douglas Anderson
2021-04-23 16:16   ` Bjorn Andersson
2021-04-23 16:46   ` Doug Anderson
2021-04-20 16:42 ` [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Doug Anderson

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