On 24/09/2019 16:17, Tomi Valkeinen wrote: > max_tu_symbol was programmed to TU_SIZE_RECOMMENDED - 1, which is not > what the spec says. The spec says: > > roundup ((input active video bandwidth in bytes/output active video > bandwidth in bytes) * tu_size) > > It is not quite clear what the above means, but calculating > max_tu_symbol = (input Bps / output Bps) * tu_size seems to work and > fixes the issues seen. > > This fixes artifacts in some videomodes (e.g. 1024x768@60 on 2-lanes & > 1.62Gbps was pretty bad for me). > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx> I could reproduce the problem and see that the patch fixes it, so: Tested-by: Jyri Sarha <jsarha@xxxxxx> > --- > drivers/gpu/drm/bridge/tc358767.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c > index 13ade28a36a8..b6aa1bd47e1d 100644 > --- a/drivers/gpu/drm/bridge/tc358767.c > +++ b/drivers/gpu/drm/bridge/tc358767.c > @@ -677,6 +677,8 @@ static int tc_set_video_mode(struct tc_data *tc, > int upper_margin = mode->vtotal - mode->vsync_end; > int lower_margin = mode->vsync_start - mode->vdisplay; > int vsync_len = mode->vsync_end - mode->vsync_start; > + u32 bits_per_pixel = 24; > + u32 in_bw, out_bw; > > /* > * Recommended maximum number of symbols transferred in a transfer unit: > @@ -684,7 +686,10 @@ static int tc_set_video_mode(struct tc_data *tc, > * (output active video bandwidth in bytes)) > * Must be less than tu_size. > */ > - max_tu_symbol = TU_SIZE_RECOMMENDED - 1; > + > + in_bw = mode->clock * bits_per_pixel / 8; > + out_bw = tc->link.base.num_lanes * tc->link.base.rate; > + max_tu_symbol = DIV_ROUND_UP(in_bw * TU_SIZE_RECOMMENDED, out_bw); > > dev_dbg(tc->dev, "set mode %dx%d\n", > mode->hdisplay, mode->vdisplay); > -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
