On Thu, Feb 25, 2021 at 7:01 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> clang points out that the new logic uses an always-uninitialized
> array index:
>
> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9810:38: 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:9720:7: note: initialize the variable 'i' to silence this warning
>
> My best guess is that the index should have been returned by the
> parse_hdmi_amd_vsdb() function that walks an array here, so do that.
>
> Fixes: f9b4f20c4777 ("drm/amd/display: Add Freesync HDMI support to DM")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> 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 b19b93c74bae..667c0d52dbfa 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -9736,7 +9736,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector,
> return false;
> }
>
> -static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> +static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
> {
> uint8_t *edid_ext = NULL;
> @@ -9746,7 +9746,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> /*----- drm_find_cea_extension() -----*/
> /* No EDID or EDID extensions */
> if (edid == NULL || edid->extensions == 0)
> - return false;
> + return -ENODEV;
>
> /* Find CEA extension */
> for (i = 0; i < edid->extensions; i++) {
> @@ -9756,14 +9756,15 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
> }
>
> if (i == edid->extensions)
> - return false;
> + return -ENODEV;
>
> /*----- cea_db_offsets() -----*/
> if (edid_ext[0] != CEA_EXT)
> - return false;
> + return -ENODEV;
>
> valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info);
> - return valid_vsdb_found;
> +
> + return valid_vsdb_found ? i : -ENODEV;
Thanks for the patch!
I don't think we need a local variable to store the return value from
one function call that's immediately returned, ie.
return parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info) ?
i : -ENODEV;
would suffice, but the patch is still fine as is.
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> }
>
> void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> @@ -9781,7 +9782,6 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> struct amdgpu_device *adev = drm_to_adev(dev);
> bool freesync_capable = false;
> struct amdgpu_hdmi_vsdb_info vsdb_info = {0};
> - bool hdmi_valid_vsdb_found = false;
>
> if (!connector->state) {
> DRM_ERROR("%s - Connector has no state", __func__);
> @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
> }
> }
> } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
> - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
> - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) {
> + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
> + if (i >= 0 && vsdb_info.freesync_supported) {
reusing `i` here is safe, for now, but reuse of variables like this in
separate branches like this might not get noticed if the function is
amended in the future.
> timing = &edid->detailed_timings[i];
> data = &timing->data.other_data;
>
> --
> 2.29.2
>
--
Thanks,
~Nick Desaulniers
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
