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

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(+)

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);
>   };
>   
>   /**

On Fri 22 Apr 16:07 PDT 2022, Dmitry Baryshkov wrote:
> On 23/04/2022 01:32, Bjorn Andersson wrote:
[..]
> > 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().
> 

Are you saying that you have code ready and being merged into linux-next
that I should redesign this on top of, or that you're planning to write
some code in the future and DisplayPort support have to wait until then?

> >   };
> >   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.
> 

There's a slight mishmash here, because the device used to initialize
the connector is the drm_dev, but we need the actual fwnode of the DP
device associated with the connector.

So I think this is how it needs to be done.

Regards,
Bjorn