Hi Laurent,
On 14/09/18 10:10, Laurent Pinchart wrote:
> DSYSR is a DU channel register that also contains group fields. It is
> thus written to by both the group and CRTC code, using read-update-write
> sequences. As the register isn't initialized explicitly at startup time,
> this can lead to invalid or otherwise unexpected values being written to
> some of the fields if they have been modified by the firmware or just
> not reset properly.
>
> To fix this we can write a fully known value to the DSYSR register when
> turning a channel's functional clock on. However, the mix of group and
> channel fields complicate this. A simpler solution is to cache the
> register and initialize the cached value to the desired hardware
> defaults.
Great, this looks good to me, and is less overhead than pulling in a
full reg-cache when we only need a single register handled.
> Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
> Tested-by: Jacopo Mondi <jacopo+rene...@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com>
> ---
> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 16 ++++++++--------
> drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 5 +++++
> drivers/gpu/drm/rcar-du/rcar_du_group.c | 7 ++++---
> 3 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index 2f8776c1ec8f..f827fccf6416 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -57,13 +57,12 @@ static void rcar_du_crtc_set(struct rcar_du_crtc *rcrtc,
> u32 reg, u32 set)
> rcar_du_read(rcdu, rcrtc->mmio_offset + reg) | set);
> }
>
> -static void rcar_du_crtc_clr_set(struct rcar_du_crtc *rcrtc, u32 reg,
> - u32 clr, u32 set)
> +void rcar_du_crtc_dsysr_clr_set(struct rcar_du_crtc *rcrtc, u32 clr, u32 set)
> {
> struct rcar_du_device *rcdu = rcrtc->group->dev;
> - u32 value = rcar_du_read(rcdu, rcrtc->mmio_offset + reg);
>
> - rcar_du_write(rcdu, rcrtc->mmio_offset + reg, (value & ~clr) | set);
> + rcrtc->dsysr = (rcrtc->dsysr & ~clr) | set;
> + rcar_du_write(rcdu, rcrtc->mmio_offset + DSYSR, rcrtc->dsysr);
> }
>
> /*
> -----------------------------------------------------------------------------
> @@ -576,9 +575,9 @@ static void rcar_du_crtc_start(struct rcar_du_crtc *rcrtc)
> * actively driven).
> */
> interlaced = rcrtc->crtc.mode.flags & DRM_MODE_FLAG_INTERLACE;
> - rcar_du_crtc_clr_set(rcrtc, DSYSR, DSYSR_TVM_MASK | DSYSR_SCM_MASK,
> - (interlaced ? DSYSR_SCM_INT_VIDEO : 0) |
> - DSYSR_TVM_MASTER);
> + rcar_du_crtc_dsysr_clr_set(rcrtc, DSYSR_TVM_MASK | DSYSR_SCM_MASK,
> + (interlaced ? DSYSR_SCM_INT_VIDEO : 0) |
> + DSYSR_TVM_MASTER);
>
> rcar_du_group_start_stop(rcrtc->group, true);
> }
> @@ -645,7 +644,7 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc)
> * Select switch sync mode. This stops display operation and configures
> * the HSYNC and VSYNC signals as inputs.
> */
> - rcar_du_crtc_clr_set(rcrtc, DSYSR, DSYSR_TVM_MASK, DSYSR_TVM_SWITCH);
> + rcar_du_crtc_dsysr_clr_set(rcrtc, DSYSR_TVM_MASK, DSYSR_TVM_SWITCH);
>
> rcar_du_group_start_stop(rcrtc->group, false);
> }
> @@ -1121,6 +1120,7 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int swindex,
> rcrtc->group = rgrp;
> rcrtc->mmio_offset = mmio_offsets[hwindex];
> rcrtc->index = hwindex;
> + rcrtc->dsysr = (rcrtc->index % 2 ? 0 : DSYSR_DRES) | DSYSR_TVM_TVSYNC;
>
> if (rcar_du_has(rcdu, RCAR_DU_FEATURE_VSP1_SOURCE))
> primary = &rcrtc->vsp->planes[rcrtc->vsp_pipe].plane;
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> index 4990bbe9ba26..59ac6e7d22c9 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> @@ -30,6 +30,7 @@ struct rcar_du_vsp;
> * @mmio_offset: offset of the CRTC registers in the DU MMIO block
> * @index: CRTC software and hardware index
> * @initialized: whether the CRTC has been initialized and clocks enabled
> + * @dsysr: cached value of the DSYSR register
> * @vblank_enable: whether vblank events are enabled on this CRTC
> * @event: event to post when the pending page flip completes
> * @flip_wait: wait queue used to signal page flip completion
> @@ -50,6 +51,8 @@ struct rcar_du_crtc {
> unsigned int index;
> bool initialized;
>
> + u32 dsysr;
> +
> bool vblank_enable;
> struct drm_pending_vblank_event *event;
> wait_queue_head_t flip_wait;
> @@ -103,4 +106,6 @@ void rcar_du_crtc_route_output(struct drm_crtc *crtc,
> enum rcar_du_output output);
> void rcar_du_crtc_finish_page_flip(struct rcar_du_crtc *rcrtc);
>
> +void rcar_du_crtc_dsysr_clr_set(struct rcar_du_crtc *rcrtc, u32 clr, u32
> set);
> +
> #endif /* __RCAR_DU_CRTC_H__ */
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_group.c
> b/drivers/gpu/drm/rcar-du/rcar_du_group.c
> index f38703e7a10d..d85f0a1c1581 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_group.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_group.c
> @@ -202,9 +202,10 @@ void rcar_du_group_put(struct rcar_du_group *rgrp)
>
> static void __rcar_du_group_start_stop(struct rcar_du_group *rgrp, bool
> start)
> {
> - rcar_du_group_write(rgrp, DSYSR,
> - (rcar_du_group_read(rgrp, DSYSR) & ~(DSYSR_DRES | DSYSR_DEN)) |
> - (start ? DSYSR_DEN : DSYSR_DRES));
> + struct rcar_du_crtc *rcrtc = &rgrp->dev->crtcs[rgrp->index * 2];
> +
> + rcar_du_crtc_dsysr_clr_set(rcrtc, DSYSR_DRES | DSYSR_DEN,
> + start ? DSYSR_DEN : DSYSR_DRES);
> }
>
> void rcar_du_group_start_stop(struct rcar_du_group *rgrp, bool start)
>
--
Regards
--
Kieran
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