Re: [PATCH v3 2/2] drm/msm/dp: Implement oob_hotplug_event()

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 23/04/2022 01:32, Bjorn Andersson wrote:
> The Qualcomm DisplayPort driver contains traces of the necessary
> plumbing to hook up USB HPD, in the form of the dp_hpd module and the
> dp_usbpd_cb struct. Use this as basis for implementing the
> oob_hotplug_event() callback, by amending the dp_hpd module with the
> missing logic.
> 
> Overall the solution is similar to what's done downstream, but upstream
> all the code to disect the HPD notification lives on the calling side of
> drm_connector_oob_hotplug_event().
> 
> drm_connector_oob_hotplug_event() performs the lookup of the
> drm_connector based on fwnode, hence the need to assign the fwnode in
> dp_drm_connector_init().
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
> 
> Changes since v2:
> - Rebased patch
> 
>   drivers/gpu/drm/msm/dp/dp_display.c |  9 +++++++++
>   drivers/gpu/drm/msm/dp/dp_display.h |  3 +++
>   drivers/gpu/drm/msm/dp/dp_drm.c     | 11 +++++++++++
>   drivers/gpu/drm/msm/dp/dp_hpd.c     | 21 +++++++++++++++++++++
>   drivers/gpu/drm/msm/dp/dp_hpd.h     |  5 +++++
>   5 files changed, 49 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index a42732b67349..1019f6d8fd03 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -449,6 +449,14 @@ static int dp_display_usbpd_configure_cb(struct device *dev)
>   	return dp_display_process_hpd_high(dp);
>   }
>   
> +void dp_display_oob_hotplug_event(struct msm_dp *dp_display,
> +				  enum drm_connector_hpd_state hpd_state)
> +{
> +	struct dp_display_private *dp = container_of(dp_display, struct dp_display_private, dp_display);
> +
> +	dp->usbpd->oob_event(dp->usbpd, hpd_state);
> +}
> +
>   static int dp_display_usbpd_disconnect_cb(struct device *dev)
>   {
>   	struct dp_display_private *dp = dev_get_dp_display_private(dev);
> @@ -1302,6 +1310,7 @@ static int dp_display_probe(struct platform_device *pdev)
>   	dp->pdev = pdev;
>   	dp->name = "drm_dp";
>   	dp->dp_display.connector_type = desc->connector_type;
> +	dp->dp_display.dev = &pdev->dev;
>   
>   	rc = dp_init_sub_modules(dp);
>   	if (rc) {
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 7af2b186d2d9..16658270df2c 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -11,6 +11,7 @@
>   #include "disp/msm_disp_snapshot.h"
>   
>   struct msm_dp {
> +	struct device *dev;
>   	struct drm_device *drm_dev;
>   	struct device *codec_dev;
>   	struct drm_bridge *bridge;
> @@ -40,5 +41,7 @@ bool dp_display_check_video_test(struct msm_dp *dp_display);
>   int dp_display_get_test_bpp(struct msm_dp *dp_display);
>   void dp_display_signal_audio_start(struct msm_dp *dp_display);
>   void dp_display_signal_audio_complete(struct msm_dp *dp_display);
> +void dp_display_oob_hotplug_event(struct msm_dp *dp_display,
> +				  enum drm_connector_hpd_state hpd_state);
>   
>   #endif /* _DP_DISPLAY_H_ */
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index 80f59cf99089..76904b1601b1 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -123,6 +123,14 @@ static enum drm_mode_status dp_connector_mode_valid(
>   	return dp_display_validate_mode(dp_disp, mode->clock);
>   }
>   
> +static void dp_oob_hotplug_event(struct drm_connector *connector,
> +				 enum drm_connector_hpd_state hpd_state)
> +{
> +	struct msm_dp *dp_disp = to_dp_connector(connector)->dp_display;
> +
> +	dp_display_oob_hotplug_event(dp_disp, hpd_state);
> +}
> +
>   static const struct drm_connector_funcs dp_connector_funcs = {
>   	.detect = dp_connector_detect,
>   	.fill_modes = drm_helper_probe_single_connector_modes,
> @@ -130,6 +138,7 @@ static const struct drm_connector_funcs dp_connector_funcs = {
>   	.reset = drm_atomic_helper_connector_reset,
>   	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>   	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +	.oob_hotplug_event = dp_oob_hotplug_event,

We were (are) going to switch dp driver to use drm_bridge_connector (to 
fix support for bridge chains, eDP panels, etc.

So these changes must be ported to drm_bridge_connector (or we must 
abandon/defer the idea of using the bridge_connector).

For the oob_hotplug_event() callback proper support might be as simple 
as calling drm_bridge_connector_hpd_cb().

>   };
>   
>   static const struct drm_connector_helper_funcs dp_connector_helper_funcs = {
> @@ -160,6 +169,8 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
>   	if (ret)
>   		return ERR_PTR(ret);
>   
> +	connector->fwnode = fwnode_handle_get(dev_fwnode(dp_display->dev));
> +

This would be much more interesting. Supporting this in a generic way 
might be tricky. But we can still set the fwnode manually from the dp code.

>   	drm_connector_helper_add(connector, &dp_connector_helper_funcs);
>   
>   	/*
> diff --git a/drivers/gpu/drm/msm/dp/dp_hpd.c b/drivers/gpu/drm/msm/dp/dp_hpd.c
> index db98a1d431eb..cdb1feea5ebf 100644
> --- a/drivers/gpu/drm/msm/dp/dp_hpd.c
> +++ b/drivers/gpu/drm/msm/dp/dp_hpd.c
> @@ -7,6 +7,8 @@
>   
>   #include <linux/slab.h>
>   #include <linux/device.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_print.h>
>   
>   #include "dp_hpd.h"
>   
> @@ -45,6 +47,24 @@ int dp_hpd_connect(struct dp_usbpd *dp_usbpd, bool hpd)
>   	return rc;
>   }
>   
> +static void dp_hpd_oob_event(struct dp_usbpd *dp_usbpd,
> +			     enum drm_connector_hpd_state hpd_state)
> +{
> +	struct dp_hpd_private *hpd_priv = container_of(dp_usbpd, struct dp_hpd_private, dp_usbpd);
> +
> +	DRM_DEBUG_DP("hpd_state: %d connected: %d\n", hpd_state, dp_usbpd->connected);
> +
> +	if (!dp_usbpd->connected && hpd_state == DRM_CONNECTOR_HPD_HIGH) {
> +		dp_usbpd->connected = true;
> +		hpd_priv->dp_cb->configure(hpd_priv->dev);
> +	} else if (hpd_state == DRM_CONNECTOR_HPD_LOW) {
> +		dp_usbpd->connected = false;
> +		hpd_priv->dp_cb->disconnect(hpd_priv->dev);
> +	} else {
> +		hpd_priv->dp_cb->attention(hpd_priv->dev);
> +	}
> +}
> +
>   struct dp_usbpd *dp_hpd_get(struct device *dev, struct dp_usbpd_cb *cb)
>   {
>   	struct dp_hpd_private *dp_hpd;
> @@ -62,6 +82,7 @@ struct dp_usbpd *dp_hpd_get(struct device *dev, struct dp_usbpd_cb *cb)
>   	dp_hpd->dp_cb = cb;
>   
>   	dp_hpd->dp_usbpd.connect = dp_hpd_connect;
> +	dp_hpd->dp_usbpd.oob_event = dp_hpd_oob_event;
>   
>   	return &dp_hpd->dp_usbpd;
>   }
> diff --git a/drivers/gpu/drm/msm/dp/dp_hpd.h b/drivers/gpu/drm/msm/dp/dp_hpd.h
> index 8feec5aa5027..4166e5fd3156 100644
> --- a/drivers/gpu/drm/msm/dp/dp_hpd.h
> +++ b/drivers/gpu/drm/msm/dp/dp_hpd.h
> @@ -29,7 +29,9 @@ enum plug_orientation {
>    * @hpd_irq: Change in the status since last message
>    * @alt_mode_cfg_done: bool to specify alt mode status
>    * @debug_en: bool to specify debug mode
> + * @connected: cable currently connected
>    * @connect: simulate disconnect or connect for debug mode
> + * @oob_event: deliver oob event to the usbpd code
>    */
>   struct dp_usbpd {
>   	enum plug_orientation orientation;
> @@ -41,8 +43,11 @@ struct dp_usbpd {
>   	bool hpd_irq;
>   	bool alt_mode_cfg_done;
>   	bool debug_en;
> +	bool connected;
>   
>   	int (*connect)(struct dp_usbpd *dp_usbpd, bool hpd);
> +	void (*oob_event)(struct dp_usbpd *dp_usbpd,
> +			  enum drm_connector_hpd_state hpd_state);
>   };
>   
>   /**


-- 
With best wishes
Dmitry