The patch below does not apply to the 6.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.16.y git checkout FETCH_HEAD git cherry-pick -x 3556dac8289456bc8b28670546b969f543967856 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025082118-unbounded-tarnish-ef1e@gregkh' --subject-prefix 'PATCH 6.16.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3556dac8289456bc8b28670546b969f543967856 Mon Sep 17 00:00:00 2001 From: Dillon Varone dillon.varone@amd.com Date: Thu, 10 Jul 2025 20:57:37 -0400 Subject: [PATCH] drm/amd/display: Fix divide by zero when calculating min ODM factor

[WHY&HOW] If the debug option is set to disable_dsc the max slice width and/or dispclk can be zero. This causes a divide by zero when calculating the min ODM combine factor. Add a check to ensure they are valid first.

Reviewed-by: Wenjing Liu wenjing.liu@amd.com Signed-off-by: Dillon Varone dillon.varone@amd.com Signed-off-by: Wayne Lin wayne.lin@amd.com Tested-by: Daniel Wheeler daniel.wheeler@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c index a454d16e6586..1f53a9f0c0ac 100644 --- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c +++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c @@ -152,7 +152,7 @@ uint32_t dc_bandwidth_in_kbps_from_timing( }

/* Forward Declerations */ -static unsigned int get_min_slice_count_for_odm( +static unsigned int get_min_dsc_slice_count_for_odm( const struct display_stream_compressor *dsc, const struct dsc_enc_caps *dsc_enc_caps, const struct dc_crtc_timing *timing); @@ -466,7 +466,7 @@ bool dc_dsc_compute_bandwidth_range( struct dc_dsc_bw_range *range) { bool is_dsc_possible = false; - unsigned int min_slice_count; + unsigned int min_dsc_slice_count; struct dsc_enc_caps dsc_enc_caps; struct dsc_enc_caps dsc_common_caps; struct dc_dsc_config config = {0}; @@ -478,14 +478,14 @@ bool dc_dsc_compute_bandwidth_range(

get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);

- min_slice_count = get_min_slice_count_for_odm(dsc, &dsc_enc_caps, timing); + min_dsc_slice_count = get_min_dsc_slice_count_for_odm(dsc, &dsc_enc_caps, timing);

is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, &dsc_enc_caps, timing->pixel_encoding, &dsc_common_caps);

if (is_dsc_possible) is_dsc_possible = setup_dsc_config(dsc_sink_caps, &dsc_enc_caps, 0, timing, - &options, link_encoding, min_slice_count, &config); + &options, link_encoding, min_dsc_slice_count, &config);

if (is_dsc_possible) is_dsc_possible = decide_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16, @@ -593,14 +593,12 @@ static void build_dsc_enc_caps(

struct dc *dc;

- memset(&single_dsc_enc_caps, 0, sizeof(struct dsc_enc_caps)); - if (!dsc || !dsc->ctx || !dsc->ctx->dc || !dsc->funcs->dsc_get_single_enc_caps) return;

dc = dsc->ctx->dc;

- if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_max_clock_khz || !dc->res_pool) + if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_max_clock_khz || !dc->res_pool || dc->debug.disable_dsc) return;

/* get max DSCCLK from clk_mgr */ @@ -634,7 +632,7 @@ static inline uint32_t dsc_div_by_10_round_up(uint32_t value) return (value + 9) / 10; }

-static unsigned int get_min_slice_count_for_odm( +static unsigned int get_min_dsc_slice_count_for_odm( const struct display_stream_compressor *dsc, const struct dsc_enc_caps *dsc_enc_caps, const struct dc_crtc_timing *timing) @@ -651,6 +649,10 @@ static unsigned int get_min_slice_count_for_odm( } }

+ /* validate parameters */ + if (max_dispclk_khz == 0 || dsc_enc_caps->max_slice_width == 0) + return 1; + /* consider minimum odm slices required due to * 1) display pipe throughput (dispclk) * 2) max image width per slice @@ -669,13 +671,12 @@ static void get_dsc_enc_caps( { memset(dsc_enc_caps, 0, sizeof(struct dsc_enc_caps));

- if (!dsc) + if (!dsc || !dsc->ctx || !dsc->ctx->dc || dsc->ctx->dc->debug.disable_dsc) return;

/* check if reported cap global or only for a single DCN DSC enc */ if (dsc->funcs->dsc_get_enc_caps) { - if (!dsc->ctx->dc->debug.disable_dsc) - dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz); + dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz); } else { build_dsc_enc_caps(dsc, dsc_enc_caps); } @@ -1295,10 +1296,10 @@ bool dc_dsc_compute_config( { bool is_dsc_possible = false; struct dsc_enc_caps dsc_enc_caps; - unsigned int min_slice_count; + unsigned int min_dsc_slice_count; get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);

- min_slice_count = get_min_slice_count_for_odm(dsc, &dsc_enc_caps, timing); + min_dsc_slice_count = get_min_dsc_slice_count_for_odm(dsc, &dsc_enc_caps, timing);

is_dsc_possible = setup_dsc_config(dsc_sink_caps, &dsc_enc_caps, @@ -1306,7 +1307,7 @@ bool dc_dsc_compute_config( timing, options, link_encoding, - min_slice_count, + min_dsc_slice_count, dsc_cfg); return is_dsc_possible; }