On Mon, 2017-05-08 at 17:18 +0530, Mahesh Kumar wrote:
> DDB minimum requirement may exceed the allocated DDB for CRTC/Pipe. This
> patch make changes to fail the flip if minimum requirement for pipe
> exceeds the total ddb allocated to the pipe.
> Previously it succeeded but making alloc_size a negative value. Which
> will make later calculations for plane ddb allocation bogus & may lead
> to screen corruption or system hang.
When sending a new version of a patch, please list the changes from the previous
version here. For example:
v2: Improve commit message.
v3: ...
> Signed-off-by: Mahesh Kumar <mahesh1.kumar@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_pm.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 2a4e9d89cd6f..0ace94d67432 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3591,6 +3591,7 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> int num_active;
> unsigned plane_data_rate[I915_MAX_PLANES] = {};
> unsigned plane_y_data_rate[I915_MAX_PLANES] = {};
> + uint16_t total_min_blocks = 0;
>
> /* Clear the partitioning for disabled planes. */
> memset(ddb->plane[pipe], 0, sizeof(ddb->plane[pipe]));
> @@ -3618,10 +3619,18 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> */
>
> for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> - alloc_size -= minimum[plane_id];
> - alloc_size -= y_minimum[plane_id];
> + total_min_blocks += minimum[plane_id];
> + total_min_blocks += y_minimum[plane_id];
> }
>
> + if ((total_min_blocks > alloc_size)) {
> + DRM_DEBUG_KMS("Requested display configuration exceeds system DDB limitations");
> + DRM_DEBUG_KMS("minimum required %d/%d\n", total_min_blocks,
> + alloc_size);
> + return-EINVAL;
> + }
The comments I made earlier [1] are still valid. With those fixed and a
changelog in the commit message,
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@xxxxxxxxx>
[1] https://lists.freedesktop.org/archives/intel-gfx/2017-April/125764.html
> +
> + alloc_size -= total_min_blocks;
> ddb->plane[pipe][PLANE_CURSOR].start = alloc->end - minimum[PLANE_CURSOR];
> ddb->plane[pipe][PLANE_CURSOR].end = alloc->end;
>
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