On 2019-10-21 3:54 a.m., Louis Li wrote: > [Why] > External monitor cannot be displayed consistently, if connecting > via this Apple dongle (A1621, USB Type-C to HDMI). > By experiments, it is confirmed that the dongle needs 200ms at least > to be ready for communication, after it sets HPD signal high. > > [How] > When receiving HPD IRQ, delay 500ms at the beginning of handle_hpd_irq(). > Then run the original procedure. > With this patch applied, the problem cannot be reproduced. > With other dongles, test results are PASS. > Test result is PASS after system resumes from suspend. > > Signed-off-by: Louis Li <Ching-shih.Li@xxxxxxx> > --- > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index 0aef92b7c037..043ddac73862 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -1025,6 +1025,11 @@ static void handle_hpd_irq(void *param) > struct drm_device *dev = connector->dev; > enum dc_connection_type new_connection_type = dc_connection_none; > > + /* Some monitors/dongles need around 200ms to be ready for communication > + * after they drive HPD signal high. > + */ > + mdelay(500); > + This sounds more like a quirk than behavior we want for all monitors, but regardless this sleep isn't the correct place for this - since this is an high priority interrupt handler this is really just blocking everything for half a second. I think it'd make more sense to queue off the work to occur half a second later. Nicholas Kazlauskas > /* In case of failure or MST no need to update connector status or notify the OS > * since (for MST case) MST does this in it's own context. > */ > _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
