Messages in this thread | | | From | Adam Ford <> | Date | Mon, 22 Apr 2024 07:09:13 -0500 | Subject | Re: [PATCH V2 2/2] drm/bridge: samsung-dsim: Fix porch calcalcuation rounding |
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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
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