On Fri, May 31, 2019 at 3:46 AM Brian Masney <masneyb@xxxxxxxxxxxxx> wrote:
>
> The mdp5 drm/kms driver currently does not work on command-mode DSI
> panels due to 'vblank wait timed out' errors. This causes a latency
> of seconds, or tens of seconds in some cases, before content is shown
> on the panel. This hardware does not have the something that we can use
> as a frame counter available when running in command mode, so we need to
> fall back to using timestamps by setting the max_vblank_count to zero.
> This can be done on a per-CRTC basis, so the convert mdp5 to use
> drm_crtc_set_max_vblank_count().
>
> This change was tested on a LG Nexus 5 (hammerhead) phone.
>
> Signed-off-by: Brian Masney <masneyb@xxxxxxxxxxxxx>
> Suggested-by: Jeffrey Hugo <jeffrey.l.hugo@xxxxxxxxx>
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@xxxxxxxxx>
> ---
> drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c | 16 +++++++++++++++-
> drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 2 +-
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c
> index c3751c95b452..6fde1097844f 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c
> @@ -450,6 +450,18 @@ static void mdp5_crtc_atomic_disable(struct drm_crtc *crtc,
> mdp5_crtc->enabled = false;
> }
>
> +static void mdp5_crtc_vblank_on(struct drm_crtc *crtc)
> +{
> + struct mdp5_crtc_state *mdp5_cstate = to_mdp5_crtc_state(crtc->state);
> + struct mdp5_interface *intf = mdp5_cstate->pipeline.intf;
> + u32 count;
> +
> + count = intf->mode == MDP5_INTF_DSI_MODE_COMMAND ? 0 : 0xffffffff;
> + drm_crtc_set_max_vblank_count(crtc, count);
> +
> + drm_crtc_vblank_on(crtc);
> +}
> +
> static void mdp5_crtc_atomic_enable(struct drm_crtc *crtc,
> struct drm_crtc_state *old_state)
> {
> @@ -486,7 +498,7 @@ static void mdp5_crtc_atomic_enable(struct drm_crtc *crtc,
> }
>
> /* Restore vblank irq handling after power is enabled */
> - drm_crtc_vblank_on(crtc);
> + mdp5_crtc_vblank_on(crtc);
>
> mdp5_crtc_mode_set_nofb(crtc);
>
> @@ -1039,6 +1051,8 @@ static void mdp5_crtc_reset(struct drm_crtc *crtc)
> mdp5_crtc_destroy_state(crtc, crtc->state);
>
> __drm_atomic_helper_crtc_reset(crtc, &mdp5_cstate->base);
> +
> + drm_crtc_vblank_reset(crtc);
> }
>
> static const struct drm_crtc_funcs mdp5_crtc_funcs = {
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> index 97179bec8902..fcb0b0455abe 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> @@ -750,7 +750,7 @@ struct msm_kms *mdp5_kms_init(struct drm_device *dev)
> dev->driver->get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos;
> dev->driver->get_scanout_position = mdp5_get_scanoutpos;
> dev->driver->get_vblank_counter = mdp5_get_vblank_counter;
> - dev->max_vblank_count = 0xffffffff;
> + dev->max_vblank_count = 0; /* max_vblank_count is set on each CRTC */
> dev->vblank_disable_immediate = true;
>
> return kms;
> --
> 2.20.1
>
