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

[Akhil P Oommen]

On 8/13/2025 11:18 AM, Dan Carpenter wrote:
> 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.

Would that make Smatch ignore usage of "dev_pm_opp_find_freq_exact()" in
other code/drivers? If yes, we may not want that.

-Akhil

> 
> regards,
> dan carpenter
> 
>