On 1/7/25 11:35 AM, Hans Verkuil wrote: > On 06/01/2025 14:40, Ricardo Ribalda wrote: >> Fps bigger than 0.000232829 fps, this fits in a 32 bit us_per_frame. >> There is no need to do a 64 bit division here. >> Also, the driver only works with whole fps. >> >> Found by cocci: >> drivers/media/platform/qcom/venus/vdec.c:488:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead. >> >> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx> >> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> >> --- >> drivers/media/platform/qcom/venus/vdec.c | 7 ++----- >> 1 file changed, 2 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c >> index 6b8906ced6bc..88f6b5a3a4fe 100644 >> --- a/drivers/media/platform/qcom/venus/vdec.c >> +++ b/drivers/media/platform/qcom/venus/vdec.c >> @@ -464,7 +464,7 @@ static int vdec_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a) >> struct venus_inst *inst = to_inst(file); >> struct v4l2_captureparm *cap = &a->parm.capture; >> struct v4l2_fract *timeperframe = &cap->timeperframe; >> - u64 us_per_frame, fps; >> + u64 us_per_frame; >> >> if (a->type != V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE && >> a->type != V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) >> @@ -486,10 +486,7 @@ static int vdec_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a) >> if (!us_per_frame || us_per_frame > USEC_PER_SEC) >> return -EINVAL; >> >> - fps = (u64)USEC_PER_SEC; >> - do_div(fps, us_per_frame); >> - >> - inst->fps = fps; >> + inst->fps = USEC_PER_SEC / (u32)us_per_frame; > > This still allows for an fps value of USEC_PER_SEC if us_per_frame is 1. > > Looking at where inst->fps is used I see: > > drivers/media/platform/qcom/venus/pm_helpers.c: return mbs * inst->fps; > drivers/media/platform/qcom/venus/venc.c: frate.framerate = inst->fps * (1 << 16); > > (mbs is at most 512x512) > > So if fps is USEC_PER_SEC those calculations will wrap around. > > What is the real maximum fps that the HW can handle? > > Stan? Bryan? It would be nice if there is a proper sanity check here. It depends on the resolution but I think we could limit the maximum to 240 FPS per instance. ~Stan
