On Wed, Oct 09, 2024 at 11:10:50AM +0530, Suraj Kandpal wrote:
> Fix the DSC flag assignment based on the dsc_slice_count returned
> to avoid divide by zero error.
>
> Fixes: 4e0837a8d00a ("drm/i915/dp_mst: Account for FEC and DSC overhead
> during BW allocation")
> Signed-off-by: Suraj Kandpal <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 4765bda154c1..bacd294d6bb6 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -105,11 +105,16 @@ static int intel_dp_mst_bw_overhead(const struct
> intel_crtc_state *crtc_state,
> if (dsc) {
> int num_joined_pipes = intel_crtc_num_joined_pipes(crtc_state);
>
> - flags |= DRM_DP_BW_OVERHEAD_DSC;
> dsc_slice_count = intel_dp_dsc_get_slice_count(connector,
>
> adjusted_mode->clock,
>
> adjusted_mode->hdisplay,
>
> num_joined_pipes);
> + /*
> + * Try with dsc only if dsc_slice_count has a sane value i.e
> value is no
> + * 0
> + */
> + if (dsc_slice_count)
> + flags |= DRM_DP_BW_OVERHEAD_DSC;
This would enable DSC, but with the wrong BW alloced. We'd need instead:
https://lore.kernel.org/all/[email protected]
> }
>
> overhead = drm_dp_bw_overhead(crtc_state->lane_count,
> --
> 2.43.2
>
