On 5/22/26 8:06 AM, Graham O'Connor wrote: > The RA620 DP-to-HDMI bridge used on the Radxa Dragon Q6A does not > acknowledge DP link training at voltage swing level 3. The bridge > requests maximum voltage swing but never completes link training > when the driver attempts level 3, causing HDMI output to fail. > > Cap DP_TRAIN_LEVEL_MAX at 2 to match the behaviour of the vendor > kernel, where link training completes successfully at level 2. > This allows the RA620 bridge to establish a stable HDMI connection. > > Tested on Radxa Dragon Q6A (QCS6490) with RA620 DP-to-HDMI bridge > > Signed-off-by: Graham O'Connor <[email protected]> > --- > drivers/gpu/drm/msm/dp/dp_link.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/dp/dp_link.h > b/drivers/gpu/drm/msm/dp/dp_link.h > index 76125e9c0..ff0d8e99d 100644 > --- a/drivers/gpu/drm/msm/dp/dp_link.h > +++ b/drivers/gpu/drm/msm/dp/dp_link.h > @@ -24,7 +24,7 @@ struct msm_dp_link_info { > unsigned long capabilities; > }; > > -#define DP_TRAIN_LEVEL_MAX 3 > +#define DP_TRAIN_LEVEL_MAX 2
You're limiting this value for *all* devices featuring a Qualcomm SoC with a DP controller. Instead, if this is really an issue that results from the bridge's capabilities (which could potentially only be a symptom, not the cause), this should be somehow limited to the specific bridge itself Konrad
