Hi

Am 17.08.21 um 21:50 schrieb Daniel Vetter:

On Tue, Aug 17, 2021 at 8:16 PM Thomas Zimmermann tzimmermann@suse.de wrote:

...

Initialize delta variable in PLL compute function for G200SE, rev 00 to the maximum value. Fixes uninitialized usage.

smatch warnings: drivers/gpu/drm/mgag200/mgag200_pll.c:142 mgag200_pixpll_compute_g200se_00() \ error: uninitialized symbol 'delta'.

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: 2545ac960364 ("drm/mgag200: Abstract pixel PLL via struct mgag200_pll") Reported-by: kernel test robot lkp@intel.com Reported-by: Dan Carpenter dan.carpenter@oracle.com Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Sam Ravnborg sam@ravnborg.org Cc: Dave Airlie airlied@redhat.com Cc: dri-devel@lists.freedesktop.org

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

I checked a bit your integer types, and there's a fair bit of inconsistency for what you're using for clock. unsigned int, long, int can all be found somewhere. But that's different story.

Better not look at the PLL code if you value your eyesight. I untangled the computation of the values from the register setup, but I don't dare to change the algorithms.

In principle, most devices should be able to share a single algorithm for computing the values and writing them out. But somehow they all differ. Maybe some minimal cleanup can be done. Without actual HW for testing, I'd rather not touch the logic.

Best regards Thomas

-Daniel

...

---

drivers/gpu/drm/mgag200/mgag200_pll.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_pll.c b/drivers/gpu/drm/mgag200/mgag200_pll.c index 7c903cf19c0d..e9ae22b4f813 100644 --- a/drivers/gpu/drm/mgag200/mgag200_pll.c +++ b/drivers/gpu/drm/mgag200/mgag200_pll.c @@ -124,6 +124,7 @@ static int mgag200_pixpll_compute_g200se_00(struct mgag200_pll *pixpll, long clo unsigned int computed;

     m = n = p = s = 0;

•   delta = 0xffffffff;
     permitteddelta = clock * 5 / 1000;
  
     for (testp = 8; testp > 0; testp /= 2) {
  

-- 2.32.0