Re: [PATCH] drm/amdgpu/display: initialize the variable 'i'

Nathan Chancellor
2021-02-22T23:46:01Z

On Mon, Feb 22, 2021 at 11:05:17PM +0000, Simon Ser wrote:
> On Monday, February 22nd, 2021 at 8:25 PM, Souptick Joarder <jrdr.linux@gmail.com> wrote:
>
> > >> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9804:38:
> > >> warning: variable 'i' is uninitialized when used here
> > >> [-Wuninitialized]
> > timing = &edid->detailed_timings[i];
> > ^
> > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9714:7:
> > note: initialize the variable 'i' to silence this warning
> > int i;
> > ^
> > = 0
> > 1 warning generated.
> >
> > Initialize the variable 'i'.
>
> Hm, I see this variable already initialized in the loop:
>
> for (i = 0; i < 4; i++) {
>
> This is the branch agd5f/drm-next.

That is in the

if (amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_DISPLAY_PORT
|| amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_EDP) {

branch not the

} else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {

branch, where i is indeed used uninitialized like clang complains about.

I am not at all familiar with the code so I cannot say if this fix is
the proper one but it is definitely a legitimate issue.

Cheers,
Nathan

> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > ---
> > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index a22a53d..e96d3d9 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -9717,7 +9717,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> > void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> > struct edid *edid)
> > {
> > - int i;
> > + int i = 0;
> > struct detailed_timing *timing;
> > struct detailed_non_pixel *data;
> > struct detailed_data_monitor_range *range;
> > --
> > 1.9.1