[PATCH] drm: bridge: dw_hdmi: fix connector access for scdc

[PATCH] drm: bridge: dw_hdmi: fix connector access for scdc

[Adrián Larumbe]

Commit 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs") changed the scdc
interface to pick up an i2c adapter from a connector instead. However, in
the case of dw-hdmi, the wrong connector was being used to pass i2c adapter
information, since dw-hdmi's embedded connector structure is only populated
when the bridge attachment callback explicitly asks for it.

drm-meson is handling connector creation, so this won't happen, leading to
a NULL pointer dereference.

Fix it by having scdc functions access dw-hdmi's current connector pointer
instead, which is assigned during the bridge enablement stage.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Fixes: 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs")
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 0accfb51509c..69c0e80b8525 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -1412,9 +1412,9 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi,
 	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
 	if (dw_hdmi_support_scdc(hdmi, display)) {
 		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
-			drm_scdc_set_high_tmds_clock_ratio(&hdmi->connector, 1);
+			drm_scdc_set_high_tmds_clock_ratio(hdmi->curr_conn, 1);
 		else
-			drm_scdc_set_high_tmds_clock_ratio(&hdmi->connector, 0);
+			drm_scdc_set_high_tmds_clock_ratio(hdmi->curr_conn, 0);
 	}
 }
 EXPORT_SYMBOL_GPL(dw_hdmi_set_high_tmds_clock_ratio);
@@ -2102,7 +2102,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 				min_t(u8, bytes, SCDC_MIN_SOURCE_VERSION));
 
 			/* Enabled Scrambling in the Sink */
-			drm_scdc_set_scrambling(&hdmi->connector, 1);
+			drm_scdc_set_scrambling(hdmi->curr_conn, 1);
 
 			/*
 			 * To activate the scrambler feature, you must ensure
@@ -2118,7 +2118,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 			hdmi_writeb(hdmi, 0, HDMI_FC_SCRAMBLER_CTRL);
 			hdmi_writeb(hdmi, (u8)~HDMI_MC_SWRSTZ_TMDSSWRST_REQ,
 				    HDMI_MC_SWRSTZ);
-			drm_scdc_set_scrambling(&hdmi->connector, 0);
+			drm_scdc_set_scrambling(hdmi->curr_conn, 0);
 		}
 	}
 
@@ -3546,6 +3546,7 @@ struct dw_hdmi *dw_hdmi_probe(struct platform_device *pdev,
 	hdmi->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID
 			 | DRM_BRIDGE_OP_HPD;
 	hdmi->bridge.interlace_allowed = true;
+	hdmi->bridge.ddc = hdmi->ddc;
 #ifdef CONFIG_OF
 	hdmi->bridge.of_node = pdev->dev.of_node;
 #endif
-- 
2.40.0

Re: [PATCH] drm: bridge: dw_hdmi: fix connector access for scdc

[Neil Armstrong]

Hi !

On 01/06/2023 14:31, Adrián Larumbe wrote:
> Commit 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs") changed the scdc
> interface to pick up an i2c adapter from a connector instead. However, in
> the case of dw-hdmi, the wrong connector was being used to pass i2c adapter
> information, since dw-hdmi's embedded connector structure is only populated
> when the bridge attachment callback explicitly asks for it.
> 
> drm-meson is handling connector creation, so this won't happen, leading to
> a NULL pointer dereference.
> 
> Fix it by having scdc functions access dw-hdmi's current connector pointer
> instead, which is assigned during the bridge enablement stage.
> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
> Fixes: 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs")

Fixes should go first.

I missed again this change because you again used my old baylibre address,
but git-send-email should not use it anymore since a .mailmap entry exists
upstream since september 2022.

Anyway, please use get_maintainers on the current working tree or use b4 to
get the most recent maintainers, reviewers & list emails.

> ---
>   drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index 0accfb51509c..69c0e80b8525 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -1412,9 +1412,9 @@ void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi,
>   	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
>   	if (dw_hdmi_support_scdc(hdmi, display)) {
>   		if (mtmdsclock > HDMI14_MAX_TMDSCLK)
> -			drm_scdc_set_high_tmds_clock_ratio(&hdmi->connector, 1);
> +			drm_scdc_set_high_tmds_clock_ratio(hdmi->curr_conn, 1);
>   		else
> -			drm_scdc_set_high_tmds_clock_ratio(&hdmi->connector, 0);
> +			drm_scdc_set_high_tmds_clock_ratio(hdmi->curr_conn, 0);
>   	}
>   }
>   EXPORT_SYMBOL_GPL(dw_hdmi_set_high_tmds_clock_ratio);
> @@ -2102,7 +2102,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>   				min_t(u8, bytes, SCDC_MIN_SOURCE_VERSION));
>   
>   			/* Enabled Scrambling in the Sink */
> -			drm_scdc_set_scrambling(&hdmi->connector, 1);
> +			drm_scdc_set_scrambling(hdmi->curr_conn, 1);
>   
>   			/*
>   			 * To activate the scrambler feature, you must ensure
> @@ -2118,7 +2118,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>   			hdmi_writeb(hdmi, 0, HDMI_FC_SCRAMBLER_CTRL);
>   			hdmi_writeb(hdmi, (u8)~HDMI_MC_SWRSTZ_TMDSSWRST_REQ,
>   				    HDMI_MC_SWRSTZ);
> -			drm_scdc_set_scrambling(&hdmi->connector, 0);
> +			drm_scdc_set_scrambling(hdmi->curr_conn, 0);
>   		}
>   	}
>   
> @@ -3546,6 +3546,7 @@ struct dw_hdmi *dw_hdmi_probe(struct platform_device *pdev,
>   	hdmi->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID
>   			 | DRM_BRIDGE_OP_HPD;
>   	hdmi->bridge.interlace_allowed = true;
> +	hdmi->bridge.ddc = hdmi->ddc;

I missed this one on my change...

>   #ifdef CONFIG_OF
>   	hdmi->bridge.of_node = pdev->dev.of_node;
>   #endif

I'll add:
Reported-by: Lukas F. Hartmann <lukas@mntre.com>

while applying and:

Acked-by: Neil Armstrong <neil.armstrong@linaro.org>

Thanks,
Neil

Re: [PATCH] drm: bridge: dw_hdmi: fix connector access for scdc

[Neil Armstrong]

Hi,

On Thu, 01 Jun 2023 13:31:53 +0100, Adrián Larumbe wrote:
> Commit 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs") changed the scdc
> interface to pick up an i2c adapter from a connector instead. However, in
> the case of dw-hdmi, the wrong connector was being used to pass i2c adapter
> information, since dw-hdmi's embedded connector structure is only populated
> when the bridge attachment callback explicitly asks for it.
> 
> drm-meson is handling connector creation, so this won't happen, leading to
> a NULL pointer dereference.
> 
> [...]

Thanks, Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-fixes)

[1/1] drm: bridge: dw_hdmi: fix connector access for scdc
      https://cgit.freedesktop.org/drm/drm-misc/commit/?id=98703e4e061fb8715c7613cd227e32cdfd136b23

-- 
Neil