Hi Tom, Heiko,
On 3/16/23 15:05, Heiko Stuebner wrote:
> Am Donnerstag, 16. März 2023, 14:23:02 CET schrieb Tom Rix:
>> clang reportes this error
>> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2322:8: error:
>> variable 'possible_crtcs' is used uninitialized whenever 'if'
>> condition is false [-Werror,-Wsometimes-uninitialized]
>> if (vp) {
>> ^~
>> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2336:36: note:
>> uninitialized use occurs here
>> ret = vop2_plane_init(vop2, win, possible_crtcs);
>> ^~~~~~~~~~~~~~
>> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2322:4:
>> note: remove the 'if' if its condition is always true
>> if (vp) {
>> ^~~~~~~~
>>
>> The else-statement changes the win->type to OVERLAY without setting the
>> possible_crtcs variable. Rework the block, initialize possible_crtcs to
>> 0 to remove the else-statement. Split the else-if-statement out to its
>> own if-statement so the OVERLAY check will catch when the win-type has
>> been changed.
>>
>> Fixes: 368419a2d429 ("drm/rockchip: vop2: initialize possible_crtcs properly")
>> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
>> ---
>> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 9 ++++-----
>> 1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>> index 03ca32cd2050..fce992c3506f 100644
>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>> @@ -2301,7 +2301,7 @@ static int vop2_create_crtcs(struct vop2 *vop2)
>> nvp = 0;
>> for (i = 0; i < vop2->registered_num_wins; i++) {
>> struct vop2_win *win = &vop2->win[i];
>> - u32 possible_crtcs;
>> + u32 possible_crtcs = 0;
>>
>> if (vop2->data->soc_id == 3566) {
>> /*
>> @@ -2327,12 +2327,11 @@ static int vop2_create_crtcs(struct vop2 *vop2)
>> /* change the unused primary window to overlay window */
>> win->type = DRM_PLANE_TYPE_OVERLAY;
>> }
>> - } else if (win->type == DRM_PLANE_TYPE_OVERLAY) {
>> - possible_crtcs = (1 << nvps) - 1;
>> - } else {
>> - possible_crtcs = 0;
>> }
>>
>> + if (win->type == DRM_PLANE_TYPE_OVERLAY)
>> + possible_crtcs = (1 << nvps) - 1;
>> +
>
> After a long hard stare at the code in question, I think doing it this
> way looks like the correct one, as as you mention in the commit message
> the first "if" will change the win->type to OVERLAY in one case, but this
> then will never be added.
>
> Michael, do you agree/disagree?
Shoot, this bit of code is more complicated than I believed it would be.
Yes, Tom's patch makes sense to me. But having overlooked the win->type
change in the if-clause makes me think I shouldn't be the judge of that
:-) Still,
Acked-by: Michael Riesch <michael.riesch@xxxxxxxxxxxxxx>
Thanks for fixing it and best regards,
Michael
>
>
> Thanks
> Heiko
>
> https://lore.kernel.org/r/20230315090158.2442771-1-michael.riesch@xxxxxxxxxxxxxx
>
>> ret = vop2_plane_init(vop2, win, possible_crtcs);
>> if (ret) {
>> drm_err(vop2->drm, "failed to init plane %s: %d\n",
>>
>
>
>
>
