Re: [PATCH 27/33] drm/panel-simple: Fix dotclock for Sharp LQ035Q7DB03

Ville Syrjälä
2020-03-03T14:50:02Z

On Mon, Mar 02, 2020 at 11:40:07PM +0200, Vladimir Zapolskiy wrote:
> Hi Ville,
>
> On 3/2/20 10:34 PM, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > The currently listed dotclock disagrees with the currently
> > listed vrefresh rate. Change the dotclock to match the vrefresh.
> >
> > Someone tell me which (if either) of the dotclock or vreresh is
> > correct?
>
> yes, I will tell you, see my answer below.
>
> Adding Linus as a person who may be interested in PL111 specifics.
>
> > Cc: Vladimir Zapolskiy <vz@mleia.com>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Thierry Reding <treding@nvidia.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> > drivers/gpu/drm/panel/panel-simple.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> > index 3012b47c1e4e..7526af2d6d95 100644
> > --- a/drivers/gpu/drm/panel/panel-simple.c
> > +++ b/drivers/gpu/drm/panel/panel-simple.c
> > @@ -2949,7 +2949,7 @@ static const struct panel_desc sharp_lq070y3dg3b = {
> > };
> >
> > static const struct drm_display_mode sharp_lq035q7db03_mode = {
> > - .clock = 5500,
> > + .clock = 5419,
> > .hdisplay = 240,
> > .hsync_start = 240 + 16,
> > .hsync_end = 240 + 16 + 7,
> >
>
> Here .clock is correct, you may find the usage of the panel in
> lpc3250-phy3250.dts example, and the PL111 controller on the SoC
> won't be able to provide the exactly computed `.clock = 5419'.

OK, I'll drop this one.

>
> So, I have to NAK this change, in this example the difference
> between the declared and the computed .vreresh is one Hz, which
> I hope can be accepted as negligible and ignorable, otherwise,
> if you insist, please correct the .vrefresh from 60 to 61.

I'm going to nuke .vrefresh entirely.

--
Ville Syrjälä
Intel