From d49564a5f7e23f08486697080e0006c606c5ebd2 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Fri, 19 Sep 2025 22:29:58 +0300 Subject: [PATCH] drm/i915: Make wm latencies monotonic MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Some systems (eg. LNL Lenovo Thinkapd X1 Carbon) declare semi-bogus non-monotonic WM latency values: WM0 latency not provided WM1 latency 100 usec WM2 latency 100 usec WM3 latency 100 usec WM4 latency 93 usec WM5 latency 100 usec Apparently Windows just papers over the issue by bumping the latencies for the higher watermark levels to make them monotonic again. Do the same. Cc: Luca Coelho Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20250919193000.17665-12-ville.syrjala@linux.intel.com Reviewed-by: Luca Coelho --- drivers/gpu/drm/i915/display/skl_watermark.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c index d83772c6ea9a3..2a40c135cb96a 100644 --- a/drivers/gpu/drm/i915/display/skl_watermark.c +++ b/drivers/gpu/drm/i915/display/skl_watermark.c @@ -3236,6 +3236,19 @@ static void sanitize_wm_latency(struct intel_display *display) wm[level] = 0; } +static void make_wm_latency_monotonic(struct intel_display *display) +{ + u16 *wm = display->wm.skl_latency; + int level, num_levels = display->wm.num_levels; + + for (level = 1; level < num_levels; level++) { + if (wm[level] == 0) + break; + + wm[level] = max(wm[level], wm[level-1]); + } +} + static void adjust_wm_latency(struct intel_display *display) { @@ -3246,6 +3259,8 @@ adjust_wm_latency(struct intel_display *display) sanitize_wm_latency(display); + make_wm_latency_monotonic(display); + /* * WaWmMemoryReadLatency * -- 2.47.3