Boris Brezillon <boris.brezillon@xxxxxxxxxxx> writes:
> We are about to use vc4_plane_mode_set() in the async check path, and
> async updates require that LBM size stay the same since they reuse the
> LBM from the previous state. So we definitely don't want to allocate a
> new LBM region that we know for sure will be free right away.
>
> Move the LBM allocation out of vc4_plane_mode_set() and call the new
> function (vc4_plane_update_lbm()) from vc4_plane_atomic_check().
>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/vc4/vc4_drv.h | 1 +
> drivers/gpu/drm/vc4/vc4_plane.c | 82 ++++++++++++++++++++++-----------
> 2 files changed, 55 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index bd6ef1f31822..9ed05fb61eb6 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -338,6 +338,7 @@ struct vc4_plane_state {
> u32 pos0_offset;
> u32 pos2_offset;
> u32 ptr0_offset;
> + u32 lbm_offset;
>
> /* Offset where the plane's dlist was last stored in the
> * hardware at vc4_crtc_atomic_flush() time.
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index f6e3e8d33115..392a51f2bf8f 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -452,6 +452,43 @@ static void vc4_write_scaling_parameters(struct drm_plane_state *state,
> }
> }
>
> +static int vc4_plane_update_lbm(struct drm_plane_state *state)
> +{
> + struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
> + struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> + unsigned long irqflags;
> + u32 lbm_size;
> +
> + lbm_size = vc4_lbm_size(state);
> + if (!lbm_size)
> + return 0;
> +
> + if (WARN_ON(!vc4_state->lbm_offset))
> + return -EINVAL;
> +
> + /* Allocate the LBM memory that the HVS will use for temporary
> + * storage due to our scaling/format conversion.
> + */
> + if (!vc4_state->lbm.allocated) {
> + int ret;
> +
> + spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> + ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> + &vc4_state->lbm,
> + lbm_size, 32, 0, 0);
> + spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> +
> + if (ret)
> + return ret;
> + } else {
> + WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> + }
> +
> + vc4_state->dlist[vc4_state->lbm_offset] = vc4_state->lbm.start;
> +
> + return 0;
> +}
> +
> /* Writes out a full display list for an active plane to the plane's
> * private dlist state.
> */
> @@ -469,31 +506,12 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> bool mix_plane_alpha;
> bool covers_screen;
> u32 scl0, scl1, pitch0;
> - u32 lbm_size, tiling;
> - unsigned long irqflags;
> + u32 tiling;
> u32 hvs_format = format->hvs;
> int ret, i;
>
> - ret = vc4_plane_setup_clipping_and_scaling(state);
> - if (ret)
> - return ret;
> -
> - /* Allocate the LBM memory that the HVS will use for temporary
> - * storage due to our scaling/format conversion.
> - */
> - lbm_size = vc4_lbm_size(state);
> - if (lbm_size) {
> - if (!vc4_state->lbm.allocated) {
> - spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> - ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> - &vc4_state->lbm,
> - lbm_size, 32, 0, 0);
> - spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> - } else {
> - WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> - }
> - }
>
> + ret = vc4_plane_setup_clipping_and_scaling(state);
> if (ret)
> return ret;
>
> @@ -717,15 +735,18 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
> }
>
> + vc4_state->lbm_offset = 0;
> +
> if (vc4_state->x_scaling[0] != VC4_SCALING_NONE ||
> vc4_state->x_scaling[1] != VC4_SCALING_NONE ||
> vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
> vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> - /* LBM Base Address. */
> + /* Reserve a slot for the LBM Base Address. The real value will
> + * be set when calling vc4_plane_update_lbm().
> + */
> if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
> - vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> - vc4_dlist_write(vc4_state, vc4_state->lbm.start);
> - }
> + vc4_state->y_scaling[1] != VC4_SCALING_NONE)
> + vc4_state->lbm_offset = vc4_state->dlist_count++;
>
> if (num_planes > 1) {
> /* Emit Cb/Cr as channel 0 and Y as channel
> @@ -785,13 +806,18 @@ static int vc4_plane_atomic_check(struct drm_plane *plane,
> struct drm_plane_state *state)
> {
> struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> + int ret;
>
> vc4_state->dlist_count = 0;
>
> - if (plane_enabled(state))
> - return vc4_plane_mode_set(plane, state);
> - else
> + if (!plane_enabled(state))
> return 0;
> +
> + ret = vc4_plane_mode_set(plane, state);
> + if (ret)
> + return ret;
> +
> + return vc4_plane_update_lbm(state);
> }
Couldn't you call update_lbm() (maybe called allocate_lbm()) first, and
then leave the dlist setup as is without needing lbm_offset?
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