Hi Maxime, Chen-Yu,
When I connect my cubieboard running 4.15-rc1 to my 4k display I get no picture. Some
digging found that there is no check against the upper pixelclock limit of the HDMI
output, so X selects a 4kp60 format at 594 MHz, which obviously won't work.
I whipped up the quick patch below, but this information about the max support HDMI
frequency should probably come from the device tree. Although for the A10 and A20 I
guess it could also be hardcoded in the source since this code is only used for sun4i.
Anyway, when I use this patch I get a proper 1080p60 picture.
Regards,
Hans
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index dda904ec0534..dc2f550f54ff 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
@@ -208,8 +208,17 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector)
return ret;
}
+static int sun4i_hdmi_mode_valid(struct drm_connector *connector,
+ struct drm_display_mode *mode)
+{
+ if (mode->clock > 170000)
+ return MODE_CLOCK_HIGH;
+ return MODE_OK;
+}
+
static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = {
.get_modes = sun4i_hdmi_get_modes,
+ .mode_valid = sun4i_hdmi_mode_valid,
};
static enum drm_connector_status
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