[bug report] drm/msm/adreno: Add support for ACD

[Dan Carpenter]

On Fri, Aug 08, 2025 at 10:28:38PM +0530, Akhil P Oommen wrote:
> On 8/7/2025 9:23 PM, Dan Carpenter wrote:
> > Hello Akhil P Oommen,
> > 
> > Commit b733fe7bff8b ("drm/msm/adreno: Add support for ACD") from Apr
> > 19, 2025 (linux-next), leads to the following Smatch static checker
> > warning:
> > 
> > 	drivers/gpu/drm/msm/adreno/a6xx_gmu.c:1700 a6xx_gmu_acd_probe()
> > 	error: 'opp' dereferencing possible ERR_PTR()
> > 
> > drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> >     1668 static int a6xx_gmu_acd_probe(struct a6xx_gmu *gmu)
> >     1669 {
> >     1670         struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu);
> >     1671         struct a6xx_hfi_acd_table *cmd = &gmu->acd_table;
> >     1672         struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
> >     1673         struct msm_gpu *gpu = &adreno_gpu->base;
> >     1674         int ret, i, cmd_idx = 0;
> >     1675         extern bool disable_acd;
> >     1676 
> >     1677         /* Skip ACD probe if requested via module param */
> >     1678         if (disable_acd) {
> >     1679                 DRM_DEV_ERROR(gmu->dev, "Skipping GPU ACD probe\n");
> >     1680                 return 0;
> >     1681         }
> >     1682 
> >     1683         cmd->version = 1;
> >     1684         cmd->stride = 1;
> >     1685         cmd->enable_by_level = 0;
> >     1686 
> >     1687         /* Skip freq = 0 and parse acd-level for rest of the OPPs */
> >     1688         for (i = 1; i < gmu->nr_gpu_freqs; i++) {
> >     1689                 struct dev_pm_opp *opp;
> >     1690                 struct device_node *np;
> >     1691                 unsigned long freq;
> >     1692                 u32 val;
> >     1693 
> >     1694                 freq = gmu->gpu_freqs[i];
> >     1695                 opp = dev_pm_opp_find_freq_exact(&gpu->pdev->dev, freq, true);
> >                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > No error checking.
> 
> We are passing back a freq which we pulled out from the opp_table a few
> lines before this. So it is unlikely that this call would fail.
> 
> But it is okay to add a check here if that would make Smatch checker happy.
> 

No, no, just ignore it, if it can't fail.

Or I can add dev_pm_opp_find_freq_exact() to the "no need to check" list.
That's easy to do.

regards,
dan carpenter