| Message ID | 20241111134644.1507-1-m.masimov@maxima.ru (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | drm/mgag200: Apply upper limit for clock variable | expand |
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.masimov@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 > > >
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; clock = clock * 2; /* Permited delta is 0.5% as VESA Specification */
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.masimov@maxima.ru> --- drivers/gpu/drm/mgag200/mgag200_g200se.c | 2 ++ 1 file changed, 2 insertions(+) -- 2.39.2