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

[Vladimir Zapolskiy]

Hi Ville,

On 3/2/20 10:34 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at 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 at mleia.com>
> Cc: Rob Herring <robh at kernel.org>
> Cc: Thierry Reding <treding at nvidia.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at 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'.

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.

--
Best wishes,
Vladimir