Le 11/11/2024 à 14:46, Murad Masimov a écrit :
If the value of the clock variable is higher than 800000, the value of the
variable m, which is used as a divisor, will remain zero, because
(clock * testp) will be higher than vcomax in every loop iteration, which
leads to skipping every iteration and leaving variable m unmodified.

Clamp value of the clock variable to the upper limit, the same way it's done
with the lower limit.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 877507bb954e ("drm/mgag200: Provide per-device callbacks for PIXPLLC")
Signed-off-by: Murad Masimov <m.masi...@maxima.ru>
---
  drivers/gpu/drm/mgag200/mgag200_g200se.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_g200se.c 
b/drivers/gpu/drm/mgag200/mgag200_g200se.c
index 7a32d3b1d226..69402a591f59 100644
--- a/drivers/gpu/drm/mgag200/mgag200_g200se.c
+++ b/drivers/gpu/drm/mgag200/mgag200_g200se.c
@@ -218,6 +218,8 @@ static int mgag200_g200se_04_pixpllc_atomic_check(struct 
drm_crtc *crtc,

        if (clock < 25000)
                clock = 25000;
+       else if (clock > 800000)
+               clock = 800000;

Maybe:
        clock = clamp(clock, 25000, 800000);

to be less verbose?

CJ

        clock = clock * 2;

        /* Permited delta is 0.5% as VESA Specification */
--
2.39.2




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