Hi Tomi,
On Fri, Dec 01, 2017 at 02:10:42PM +0200, Tomi Valkeinen wrote:
>
> On 24/07/17 20:33, Sebastian Reichel wrote:
> > This is a workaround for a hardware bug occuring on OMAP3
> > with manually updated panels. Details about the HW bug are
> > unknown to me, but without this fix the panel refresh does
> > not work at all on Nokia N950.
> >
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/omapdrm/dss/dispc.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/omapdrm/dss/dispc.c b/drivers/gpu/drm/omapdrm/dss/dispc.c
> > index fd7504b37e3b..b6dca5ee34d4 100644
> > --- a/drivers/gpu/drm/omapdrm/dss/dispc.c
> > +++ b/drivers/gpu/drm/omapdrm/dss/dispc.c
> > @@ -1398,6 +1398,18 @@ void dispc_ovl_compute_fifo_thresholds(enum omap_plane_id plane,
> > }
> > }
> >
> > +void dispc_ovl_set_manual_fifo_threshold(enum omap_plane_id plane)
> > +{
> > + u32 fifo_low, fifo_high;
> > + bool use_fifo_merge = false;
> > + bool use_manual_update = true;
> > +
> > + dispc_ovl_compute_fifo_thresholds(plane, &fifo_low, &fifo_high,
> > + use_fifo_merge, use_manual_update);
> > +
> > + dispc_ovl_set_fifo_threshold(plane, fifo_low, fifo_high);
> > +}
> > +
> > static void dispc_ovl_set_mflag(enum omap_plane_id plane, bool enable)
> > {
> > int bit;
> > @@ -2566,6 +2578,10 @@ static int dispc_ovl_setup(enum omap_plane_id plane,
> > oi->zorder, oi->pre_mult_alpha, oi->global_alpha,
> > oi->rotation_type, replication, vm, mem_to_mem);
> >
> > + /* manual mode needs other fifo thresholds */
> > + if (mgr_fld_read(channel, DISPC_MGR_FLD_STALLMODE))
> > + dispc_ovl_set_manual_fifo_threshold(plane);
> > +
> > return r;
> > }
>
> We don't have the stallmode for all channels. And on OMAP2 it's for
> RFBI, and I don't know if that needs different thresholds or not. Also,
> I'm not sure if OMAP4-5 DSI needs this. And I think it's good to mention
> the unknown bug in the comment too. And yes, it's unknown to me too, I
> never figured it out. These thresholds just seemed to work, while the
> default did not.
>
> So I think we need to check that the platform is OMAP3 and channel is
> LCD. We can later extend that to cover OMAP4-5 if needed.
Ok. I will have a look at this later today. FWIW I test this
patchset with OMAP3 (N950) and OMAP4 (Droid 4). OMAP4 works
without this patch, but also with the changed thresholds.
-- Sebastian
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