[PATCH] omapfb: dss: Fix max fclk divider for omap36xx

[Adam Ford]

On Mon, Jul 6, 2020 at 1:02 AM Tomi Valkeinen <tomi.valkeinen at ti.com> wrote:
>
> Hi,
>
> On 03/07/2020 22:36, Sam Ravnborg wrote:
> > Hi Tomi.
> >
> > On Fri, Jul 03, 2020 at 10:17:29AM +0300, Tomi Valkeinen wrote:
> >> On 30/06/2020 21:26, Adam Ford wrote:
> >>> The drm/omap driver was fixed to correct an issue where using a
> >>> divider of 32 breaks the DSS despite the TRM stating 32 is a valid
> >>> number.  Through experimentation, it appears that 31 works, and
> >>> it is consistent with the value used by the drm/omap driver.
> >>>
> >>> This patch fixes the divider for fbdev driver instead of the drm.
> >>>
> >>> Fixes: f76ee892a99e ("omapfb: copy omapdss & displays for omapfb")
> >>>
> >>> Cc: <stable at vger.kernel.org> #4.9+
> >>> Signed-off-by: Adam Ford <aford173 at gmail.com>
> >>> ---
> >>> Linux 4.4 will need a similar patch, but it doesn't apply cleanly.
> >>>
> >>> The DRM version of this same fix is:
> >>> e2c4ed148cf3 ("drm/omap: fix max fclk divider for omap36xx")
> >>>
> >>>
> >>> diff --git a/drivers/video/fbdev/omap2/omapfb/dss/dss.c b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> >>> index 7252d22dd117..bfc5c4c5a26a 100644
> >>> --- a/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> >>> +++ b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> >>> @@ -833,7 +833,7 @@ static const struct dss_features omap34xx_dss_feats = {
> >>>    };
> >>>    static const struct dss_features omap3630_dss_feats = {
> >>> -   .fck_div_max            =       32,
> >>> +   .fck_div_max            =       31,
> >>>     .dss_fck_multiplier     =       1,
> >>>     .parent_clk_name        =       "dpll4_ck",
> >>>     .dpi_select_source      =       &dss_dpi_select_source_omap2_omap3,
> >>>
> >>
> >> Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
> > Will you apply to drm-misc?
>
> This is for fbdev, so I presume Bartlomiej will pick this one.
>
> > Note  following output from "dim fixes":
> > $ dim fixes f76ee892a99e
> > Fixes: f76ee892a99e ("omapfb: copy omapdss & displays for omapfb")
> > Cc: Tomi Valkeinen <tomi.valkeinen at ti.com>
> > Cc: Dave Airlie <airlied at gmail.com>
> > Cc: Rob Clark <robdclark at gmail.com>
> > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Cc: Sam Ravnborg <sam at ravnborg.org>
> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie at samsung.com>
> > Cc: Jason Yan <yanaijie at huawei.com>
> > Cc: "Andrew F. Davis" <afd at ti.com>
> > Cc: YueHaibing <yuehaibing at huawei.com>
> > Cc: <stable at vger.kernel.org> # v4.5+
> >
> > Here it says the fix is valid from v4.5 onwards.
>
> Hmm... Adam, you marked the fix to apply to v4.9+, and then you said
> v4.4 needs a new patch (that's before the big copy/rename). Did you
> check the versions between 4.4 and 4.9? I would guess this one applies
> to v4.5+.

I only tried 4.9 because it's listed as an LTS kernel.  The stuff
between 4.4 and 4.9 were EOL, so I didn't go back further.    The 4.5+
is probably more accurate.  I would like to do the same thing for the
4.4 kernel, but I am not sure the proper way to do that.

adam
>
>   Tomi
>
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