media: venus: vdec: Clamp param smaller than 1fps and bigger than 240.

The driver uses "whole" fps in all its calculations (e.g. in
load_per_instance()). Those calculation expect an fps bigger than 1, and
not big enough to overflow.

Clamp the value if the user provides a param that will result in an invalid
fps.

Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Closes: https://lore.kernel.org/linux-media/f11653a7-bc49-48cd-9cdb-1659147453e4@xs4all.nl/T/#m91cd962ac942834654f94c92206e2f85ff7d97f0
Fixes: 7472c1c ("[media] media: venus: vdec: add video decoder files")
Cc: stable@vger.kernel.org
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> # qrb5615-rb5
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
[bod: Change "parm" to "param"]
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

Author: ribalda

drivers/media/platform/qcom/venus/core.h

@@ -28,6 +28,8 @@
 #define VIDC_RESETS_NUM_MAX		2
 #define VIDC_MAX_HIER_CODING_LAYER 6
 
+#define VENUS_MAX_FPS			240
+
 extern int venus_fw_debug;
 
 struct freq_tbl {

drivers/media/platform/qcom/venus/vdec.c

@@ -481,11 +481,10 @@ static int vdec_s_parm(struct file *file, void *fh, struct v4l2_streamparm *a)
 	us_per_frame = timeperframe->numerator * (u64)USEC_PER_SEC;
 	do_div(us_per_frame, timeperframe->denominator);
 
-	if (!us_per_frame)
-		return -EINVAL;
-
+	us_per_frame = clamp(us_per_frame, 1, USEC_PER_SEC);
 	fps = (u64)USEC_PER_SEC;
 	do_div(fps, us_per_frame);
+	fps = min(VENUS_MAX_FPS, fps);
 
 	inst->fps = fps;
 	inst->timeperframe = *timeperframe;