Re: [PATCH v2 01/38] drm/msm/dp: split msm_dp_panel_read_sink_caps() into two parts and drop panel drm_edid

[Yongxing Mou <quic_yongmou@xxxxxxxxxxx>]

On 2025/6/9 20:41, Dmitry Baryshkov wrote:
> On Mon, Jun 09, 2025 at 08:21:20PM +0800, Yongxing Mou wrote:
> > From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> >
> > In preparation of DP MST where link caps are read for the
> > immediate downstream device and the edid is read through
>
> EDID, not edid. Please review all your patches for up/down case.
Got it. Thanks~
> > sideband messaging, split the msm_dp_panel_read_sink_caps() into
> > two parts which read the link parameters and the edid parts
> > respectively. Also drop the panel drm_edid cached as we actually
> > don't need it.
>
> Also => separate change.
Got it.
> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > Signed-off-by: Yongxing Mou <quic_yongmou@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/dp/dp_display.c | 13 +++++----
> >   drivers/gpu/drm/msm/dp/dp_panel.c   | 55 ++++++++++++++++++++-----------------
> >   drivers/gpu/drm/msm/dp/dp_panel.h   |  6 ++--
> >   3 files changed, 40 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> > index 6f05a939ce9e648e9601597155999b6f85adfcff..4a9b65647cdef1ed6c3bb851f93df0db8be977af 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -389,7 +389,11 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
> >   
> >   	dp->link->lttpr_count = msm_dp_display_lttpr_init(dp, dpcd);
> >   
> > -	rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
> > +	rc = msm_dp_panel_read_link_caps(dp->panel);
> > +	if (rc)
> > +		goto end;
> > +
> > +	rc = msm_dp_panel_read_edid(dp->panel, connector);
> >   	if (rc)
> >   		goto end;
> >   
> > @@ -720,7 +724,6 @@ static int msm_dp_irq_hpd_handle(struct msm_dp_display_private *dp, u32 data)
> >   static void msm_dp_display_deinit_sub_modules(struct msm_dp_display_private *dp)
> >   {
> >   	msm_dp_audio_put(dp->audio);
> > -	msm_dp_panel_put(dp->panel);
> >   	msm_dp_aux_put(dp->aux);
> >   }
> >   
> > @@ -783,7 +786,7 @@ static int msm_dp_init_sub_modules(struct msm_dp_display_private *dp)
> >   		rc = PTR_ERR(dp->ctrl);
> >   		DRM_ERROR("failed to initialize ctrl, rc = %d\n", rc);
> >   		dp->ctrl = NULL;
> > -		goto error_ctrl;
> > +		goto error_link;
> >   	}
> >   
> >   	dp->audio = msm_dp_audio_get(dp->msm_dp_display.pdev, dp->catalog);
> > @@ -791,13 +794,11 @@ static int msm_dp_init_sub_modules(struct msm_dp_display_private *dp)
> >   		rc = PTR_ERR(dp->audio);
> >   		pr_err("failed to initialize audio, rc = %d\n", rc);
> >   		dp->audio = NULL;
> > -		goto error_ctrl;
> > +		goto error_link;
> >   	}
> >   
> >   	return rc;
> >   
> > -error_ctrl:
> > -	msm_dp_panel_put(dp->panel);
> >   error_link:
> >   	msm_dp_aux_put(dp->aux);
> >   error:
> > diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
> > index 4e8ab75c771b1e3a2d62f75e9993e1062118482b..d9041e235104a74b3cc50ff2e307eae0c4301ef3 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_panel.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
> > @@ -118,14 +118,13 @@ static u32 msm_dp_panel_get_supported_bpp(struct msm_dp_panel *msm_dp_panel,
> >   	return min_supported_bpp;
> >   }
> >   
> > -int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> > -	struct drm_connector *connector)
> > +int msm_dp_panel_read_link_caps(struct msm_dp_panel *msm_dp_panel)
> >   {
> >   	int rc, bw_code;
> >   	int count;
> >   	struct msm_dp_panel_private *panel;
> >   
> > -	if (!msm_dp_panel || !connector) {
> > +	if (!msm_dp_panel) {
> >   		DRM_ERROR("invalid input\n");
> >   		return -EINVAL;
> >   	}
> > @@ -160,26 +159,29 @@ int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> >   
> >   	rc = drm_dp_read_downstream_info(panel->aux, msm_dp_panel->dpcd,
> >   					 msm_dp_panel->downstream_ports);
> > -	if (rc)
> > -		return rc;
> > +	return rc;
> > +}
> >   
> > -	drm_edid_free(msm_dp_panel->drm_edid);
> > +int msm_dp_panel_read_edid(struct msm_dp_panel *msm_dp_panel, struct drm_connector *connector)
> > +{
> > +	struct msm_dp_panel_private *panel;
> > +	const struct drm_edid *drm_edid;
> > +
> > +	panel = container_of(msm_dp_panel, struct msm_dp_panel_private, msm_dp_panel);
> >   
> > -	msm_dp_panel->drm_edid = drm_edid_read_ddc(connector, &panel->aux->ddc);
> > +	drm_edid = drm_edid_read_ddc(connector, &panel->aux->ddc);
> >   
> > -	drm_edid_connector_update(connector, msm_dp_panel->drm_edid);
> > +	drm_edid_connector_update(connector, drm_edid);
> >   
> > -	if (!msm_dp_panel->drm_edid) {
> > +	if (!drm_edid) {
> >   		DRM_ERROR("panel edid read failed\n");
> >   		/* check edid read fail is due to unplug */
> >   		if (!msm_dp_catalog_link_is_connected(panel->catalog)) {
> > -			rc = -ETIMEDOUT;
> > -			goto end;
> > +			return -ETIMEDOUT;
> >   		}
> >   	}
> >   
> > -end:
> > -	return rc;
> > +	return 0;
> >   }
> >   
> >   u32 msm_dp_panel_get_mode_bpp(struct msm_dp_panel *msm_dp_panel,
> > @@ -208,15 +210,20 @@ u32 msm_dp_panel_get_mode_bpp(struct msm_dp_panel *msm_dp_panel,
> >   int msm_dp_panel_get_modes(struct msm_dp_panel *msm_dp_panel,
> >   	struct drm_connector *connector)
> >   {
> > +	struct msm_dp_panel_private *panel;
> > +	const struct drm_edid *drm_edid;
> > +
> >   	if (!msm_dp_panel) {
> >   		DRM_ERROR("invalid input\n");
> >   		return -EINVAL;
> >   	}
> >   
> > -	if (msm_dp_panel->drm_edid)
> > -		return drm_edid_connector_add_modes(connector);
> > +	panel = container_of(msm_dp_panel, struct msm_dp_panel_private, msm_dp_panel);
> > +
> > +	drm_edid = drm_edid_read_ddc(connector, &panel->aux->ddc);
> > +	drm_edid_connector_update(connector, drm_edid);
>
> If EDID has been read and processed after HPD high event, why do we need
> to re-read it again? Are we expecting that EDID will change?
Here we indeed don't need to read the EDID again, so we can directly 
call drm_edid_connector_add_modes. Thanks.
> >   
> > -	return 0;
> > +	return drm_edid_connector_add_modes(connector);
> >   }
> >   
> >   static u8 msm_dp_panel_get_edid_checksum(const struct edid *edid)
> > @@ -229,6 +236,7 @@ static u8 msm_dp_panel_get_edid_checksum(const struct edid *edid)
> >   void msm_dp_panel_handle_sink_request(struct msm_dp_panel *msm_dp_panel)
> >   {
> >   	struct msm_dp_panel_private *panel;
> > +	const struct drm_edid *drm_edid;
> >   
> >   	if (!msm_dp_panel) {
> >   		DRM_ERROR("invalid input\n");
> > @@ -238,8 +246,13 @@ void msm_dp_panel_handle_sink_request(struct msm_dp_panel *msm_dp_panel)
> >   	panel = container_of(msm_dp_panel, struct msm_dp_panel_private, msm_dp_panel);
> >   
> >   	if (panel->link->sink_request & DP_TEST_LINK_EDID_READ) {
> > +		drm_edid = drm_edid_read_ddc(msm_dp_panel->connector, &panel->aux->ddc);
>
> And again....
Here we need the struct edid,since we drop the cached drm_edid, so we 
need to read it again. Or we can return the drm_edid from 
msm_dp_panel_read_edid and pass it to msm_dp_panel_handle_sink_request, 
then we don't need to read drm_edid here. Emm, I'm still a bit curious 
why we can't cache the drm_edid? It would help us to access it when 
needed. Emm, i see other drivers also cache it.
> > +
> > +		if (!drm_edid)
> > +			return;
> > +
> >   		/* FIXME: get rid of drm_edid_raw() */
> > -		const struct edid *edid = drm_edid_raw(msm_dp_panel->drm_edid);
> > +		const struct edid *edid = drm_edid_raw(drm_edid);
> >   		u8 checksum;
> >   
> >   		if (edid)
> > @@ -515,11 +528,3 @@ struct msm_dp_panel *msm_dp_panel_get(struct device *dev, struct drm_dp_aux *aux
> >   
> >   	return msm_dp_panel;
> >   }
> > -
> > -void msm_dp_panel_put(struct msm_dp_panel *msm_dp_panel)
> > -{
> > -	if (!msm_dp_panel)
> > -		return;
> > -
> > -	drm_edid_free(msm_dp_panel->drm_edid);
> > -}
>
> Too many changes to be stuffed under the hood of "Also perform foo"
Got it, thanks , will split  this patch and refactor the commit msg.
> > diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
> > index 4906f4f09f2451cfed3c1007f38b4db7dfdb1d90..7f139478e1012d5b8f1f745f0de5fc3943745428 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_panel.h
> > +++ b/drivers/gpu/drm/msm/dp/dp_panel.h
> > @@ -32,7 +32,6 @@ struct msm_dp_panel {
> >   	u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
> >   
> >   	struct msm_dp_link_info link_info;
> > -	const struct drm_edid *drm_edid;
> >   	struct drm_connector *connector;
> >   	struct msm_dp_display_mode msm_dp_mode;
> >   	struct msm_dp_panel_psr psr_cap;
> > @@ -51,7 +50,9 @@ int msm_dp_panel_timing_cfg(struct msm_dp_panel *msm_dp_panel);
> >   int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> >   		struct drm_connector *connector);
> >   u32 msm_dp_panel_get_mode_bpp(struct msm_dp_panel *msm_dp_panel, u32 mode_max_bpp,
> > -			u32 mode_pclk_khz);
> > +			      u32 mode_pclk_khz);
> > +int msm_dp_panel_read_link_caps(struct msm_dp_panel *dp_panel);
> > +int msm_dp_panel_read_edid(struct msm_dp_panel *dp_panel, struct drm_connector *connector);
> >   int msm_dp_panel_get_modes(struct msm_dp_panel *msm_dp_panel,
> >   		struct drm_connector *connector);
> >   void msm_dp_panel_handle_sink_request(struct msm_dp_panel *msm_dp_panel);
> > @@ -86,5 +87,4 @@ static inline bool is_lane_count_valid(u32 lane_count)
> >   
> >   struct msm_dp_panel *msm_dp_panel_get(struct device *dev, struct drm_dp_aux *aux,
> >   			      struct msm_dp_link *link, struct msm_dp_catalog *catalog);
> > -void msm_dp_panel_put(struct msm_dp_panel *msm_dp_panel);
> >   #endif /* _DP_PANEL_H_ */
> >
> > --
> > 2.34.1