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.
Tomi
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