drm: bridge: dw_hdmi: fix connector access for scdc

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.

Fixes: 5d844091f237 ("drm/scdc-helper: Pimp SCDC debugs")
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reported-by: Lukas F. Hartmann <lukas@mntre.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
[narmstrong: moved Fixes tag before first S-o-b and added Reported-by tag]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230601123153.196867-1-adrian.larumbe@collabora.com

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 603bb3c..3b40e0f 100644 (file)
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -1426,9 +1426,9 @@ 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);
@@ -2116,7 +2116,7 @@ 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
@@ -2132,7 +2132,7 @@ 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);
                }
        }
 
@@ -3553,6 +3553,7 @@ 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