On Sun, Oct 13, 2019 at 10:56 AM Adam Ford <aford173@xxxxxxxxx> wrote:
>
> On Wed, Oct 2, 2019 at 7:25 AM Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote:
> >
> > The OMAP36xx and AM/DM37x TRMs say that the maximum divider for DSS fclk
> > (in CM_CLKSEL_DSS) is 32. Experimentation shows that this is not
> > correct, and using divider of 32 breaks DSS with a flood or underflows
> > and sync losts. Dividers up to 31 seem to work fine.
> >
> > There is another patch to the DT files to limit the divider correctly,
> > but as the DSS driver also needs to know the maximum divider to be able
> > to iteratively find good rates, we also need to do the fix in the DSS
> > driver.
> >
>
> Tomi,
>
> Is there any way you can do a patch for the FB version for the older
> 4.9 and 4.14 kernels? I think they are still defaulting to the omapfb
> instead of DRM, so the underflow issue still appears by default and
> the patch only impacts the DRM version of the driver. If not, do you
> have any objections if I submit a patch to stable for those two LTS
> branches?
Gentle nudge on this question. I can do the work, but I just
permission so don't overstep.
adam
>
> thanks,
>
> adam
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> > Cc: Adam Ford <aford173@xxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> > drivers/gpu/drm/omapdrm/dss/dss.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/omapdrm/dss/dss.c b/drivers/gpu/drm/omapdrm/dss/dss.c
> > index e226324adb69..4bdd63b57100 100644
> > --- a/drivers/gpu/drm/omapdrm/dss/dss.c
> > +++ b/drivers/gpu/drm/omapdrm/dss/dss.c
> > @@ -1083,7 +1083,7 @@ static const struct dss_features omap34xx_dss_feats = {
> >
> > static const struct dss_features omap3630_dss_feats = {
> > .model = DSS_MODEL_OMAP3,
> > - .fck_div_max = 32,
> > + .fck_div_max = 31,
> > .fck_freq_max = 173000000,
> > .dss_fck_multiplier = 1,
> > .parent_clk_name = "dpll4_ck",
> > --
> > 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
