[PATCH 6.18 568/752] media: iris: Fix fps calculation

Sasha Levin
2026-02-28T17:56:19Z

From: Ricardo Ribalda <ribalda@chromium.org>

[ Upstream commit 71fe80364a6584f404556ac9a6a4aca4ab80fb5b ]

iris_venc_s_param() uses do_div to divide two 64 bits operators, this is
wrong. Luckily for us, both of the operators fit in 32 bits, so we can use
a normal division.

Now that we are at it, mark the fps smaller than 1 as invalid, the code
does not seem to handle them properly.

The following cocci warning is fixed with this patch:
./platform/qcom/iris/iris_venc.c:378:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead

Fixes: 4ff586ff28e3 ("media: iris: Add support for G/S_PARM for encoder video device")
Reviewed-by: Dikshita Agarwal <dikshita.agarwal@oss.qualcomm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/platform/qcom/iris/iris_venc.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_venc.c b/drivers/media/platform/qcom/iris/iris_venc.c
index 099bd5ed4ae02..c11ed778cc9e9 100644
--- a/drivers/media/platform/qcom/iris/iris_venc.c
+++ b/drivers/media/platform/qcom/iris/iris_venc.c
@@ -345,8 +345,7 @@ int iris_venc_s_param(struct iris_inst *inst, struct v4l2_streamparm *s_parm)
struct v4l2_fract *timeperframe = NULL;
u32 default_rate = DEFAULT_FPS;
bool is_frame_rate = false;
- u64 us_per_frame, fps;
- u32 max_rate;
+ u32 fps, max_rate;

int ret = 0;

@@ -368,23 +367,19 @@ int iris_venc_s_param(struct iris_inst *inst, struct v4l2_streamparm *s_parm)
timeperframe->denominator = default_rate;
}

- us_per_frame = timeperframe->numerator * (u64)USEC_PER_SEC;
- do_div(us_per_frame, timeperframe->denominator);
-
- if (!us_per_frame)
+ fps = timeperframe->denominator / timeperframe->numerator;
+ if (!fps)
return -EINVAL;

- fps = (u64)USEC_PER_SEC;
- do_div(fps, us_per_frame);
if (fps > max_rate) {
ret = -ENOMEM;
goto reset_rate;
}

if (is_frame_rate)
- inst->frame_rate = (u32)fps;
+ inst->frame_rate = fps;
else
- inst->operating_rate = (u32)fps;
+ inst->operating_rate = fps;

if ((s_parm->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE && vb2_is_streaming(src_q)) ||
(s_parm->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE && vb2_is_streaming(dst_q))) {
--
2.51.0