diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.15/950-0477-drm-vc4-Correct-DSI-divider-calculations.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.15/950-0477-drm-vc4-Correct-DSI-divider-calculations.patch | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.15/950-0477-drm-vc4-Correct-DSI-divider-calculations.patch b/target/linux/bcm27xx/patches-5.15/950-0477-drm-vc4-Correct-DSI-divider-calculations.patch new file mode 100644 index 0000000000..af258f20d1 --- /dev/null +++ b/target/linux/bcm27xx/patches-5.15/950-0477-drm-vc4-Correct-DSI-divider-calculations.patch @@ -0,0 +1,35 @@ +From 06c340cc854b1c8c275968c2830fbe8a5c3b0e4e Mon Sep 17 00:00:00 2001 +From: Dave Stevenson <dave.stevenson@raspberrypi.com> +Date: Fri, 18 Jun 2021 21:52:28 +0100 +Subject: [PATCH] drm/vc4: Correct DSI divider calculations + +The divider calculations tried to find the divider +just faster than the clock requested. However if +it required a divider of 7 then the for loop +aborted without handling the "error" case, and could +end up with a clock lower than requested. + +Correct the loop so that we always have a clock greater +than requested. + +Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com> +--- + drivers/gpu/drm/vc4/vc4_dsi.c | 6 ++---- + 1 file changed, 2 insertions(+), 4 deletions(-) + +--- a/drivers/gpu/drm/vc4/vc4_dsi.c ++++ b/drivers/gpu/drm/vc4/vc4_dsi.c +@@ -850,11 +850,9 @@ static bool vc4_dsi_encoder_mode_fixup(s + /* Find what divider gets us a faster clock than the requested + * pixel clock. + */ +- for (divider = 1; divider < 8; divider++) { +- if (parent_rate / divider < pll_clock) { +- divider--; ++ for (divider = 1; divider < 7; divider++) { ++ if (parent_rate / (divider + 1) < pll_clock) + break; +- } + } + + /* Now that we've picked a PLL divider, calculate back to its |