lkml.org 
[lkml]   [2024]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH V2 2/2] drm/bridge: samsung-dsim: Fix porch calcalcuation rounding
On Sun, Apr 21, 2024 at 9:36 AM Marek Vasut <marex@denx.de> wrote:
>
> On 2/12/24 12:09 AM, Adam Ford wrote:
> > When using video sync pulses, the HFP, HBP, and HSA are divided between
> > the available lanes if there is more than one lane. For certain
> > timings and lane configurations, the HFP may not be evenly divisible.
> > If the HFP is rounded down, it ends up being too small which can cause
> > some monitors to not sync properly. In these instances, adjust htotal
> > and hsync to round the HFP up, and recalculate the htotal.
> >
> > Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de> # Kontron BL i.MX8MM with HDMI monitor
> > Signed-off-by: Adam Ford <aford173@gmail.com>
> > ---
> > V2: No changes
> >
> > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> > index 8476650c477c..52939211fe93 100644
> > --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> > @@ -1606,6 +1606,27 @@ static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
> > adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > }
> >
> > + /*
> > + * When using video sync pulses, the HFP, HBP, and HSA are divided between
> > + * the available lanes if there is more than one lane. For certain
> > + * timings and lane configurations, the HFP may not be evenly divisible.
> > + * If the HFP is rounded down, it ends up being too small which can cause
> > + * some monitors to not sync properly. In these instances, adjust htotal
> > + * and hsync to round the HFP up, and recalculate the htotal. Through trial
> > + * and error, it appears that the HBP and HSA do not appearto need the same
> > + * correction that HFP does.
> > + */
> > + if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE && dsi->lanes > 1) {
>
> Does this also apply to mode with sync events (I suspect it does), so
> the condition here should likely be if (!...burst mode) , right ?

Thanks for the review!

I was only able to test it with the DSI->ADV6535 bridge, and I'll
admit I don't know a lot about DSI interface since I don't have a copy
of the spec to read.

Are you proposing this should be:

if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) && dsi->lanes > 1) {

I just want to make sure I understand what you're requesting.

thanks

adam

\
 
 \ /
  Last update: 2024-04-22 14:09    [W:0.121 / U:0.540 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site