Hi Nikolaus,
Le mer., févr. 2 2022 at 17:31:20 +0100, H. Nikolaus Schaller
<hns@xxxxxxxxxxxxx> a écrit :
Commit 7cd70656d1285b ("drm/bridge: display-connector: implement bus
fmts callbacks")
introduced a new mechanism to negotiate bus formats between hdmi
connector
and the synopsys hdmi driver inside the jz4780.
By this, the dw-hdmi is no longer the only bridge and sets up a list
of formats in dw_hdmi_bridge_atomic_get_output_bus_fmts().
This includes MEDIA_BUS_FMT_UYVY8_1X16 which is chosen for the jz4780
but only
produces a black screen.
This fix is based on the observation that max_bpc = 0 when running
this
function while info->bpc = 8. Since the formats checks before this
always test
for max_bpc >= info->pbc indirectly my assumption is that we must
check it
here as well.
This fix looks really strange to me, so I'll let the DRM experts
comment.
It would still be better to move the patch before the introduction of
dw-ingenic-hdmi.c, so that once this one is introduced, everything
works. This also enables bisectability.
Cheers,
-Paul
Adding the proposed patch makes the CI20/jz4780 panel work again in
MEDIA_BUS_FMT_RGB888_1X24 mode.
Fixes: 7cd70656d1285b ("drm/bridge: display-connector: implement bus
fmts callbacks")
Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
---
drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 52e7cd2e020d3..34703a15ee4ff 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2620,10 +2620,10 @@ static u32
*dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
output_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
}
- if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
+ if (max_bpc >= info->bpc && info->color_formats &
DRM_COLOR_FORMAT_YCRCB422)
output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
- if (info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
+ if (max_bpc >= info->bpc && info->color_formats &
DRM_COLOR_FORMAT_YCRCB444)
output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
/* Default 8bit RGB fallback */
--
2.33.0
