Re: [PATCH] media: iris: fix 64-bit division in iris_set_slice_count()

[Bryan O'Donoghue <bod@kernel.org>]

On 02/10/2026 08:44, Sachin Kumar Garg wrote:
> inst->fw_caps[BITRATE].value is an s64, so dividing it by the frame
> rate is a 64-bit division. On 32-bit architectures the compiler turns
> this into a call to the libgcc helper __divdi3, which the kernel does
> not provide, so the module fails to link.
> 
> The bitrate always fits in a u32, so copy it into a u32 local before
> dividing, as iris_set_peak_bitrate() already does.
> 
> Fixes: 9abcab03dbf8 ("media: iris: add support for multi_slice in iris encoder")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202610020426.oUzBZ3mH-lkp@intel.com/
> 
> Signed-off-by: Sachin Kumar Garg <sachin.garg@oss.qualcomm.com>
> ---
> The original commit is 5f21cd9a4ae4 in next-20261001 and is
> 9abcab03dbf8 in the current venus-iris-next branch.
> ---
>   drivers/media/platform/qcom/iris/iris_ctrls.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/qcom/iris/iris_ctrls.c b/drivers/media/platform/qcom/iris/iris_ctrls.c
> index 8c4c47944f22..06d99b18310b 100644
> --- a/drivers/media/platform/qcom/iris/iris_ctrls.c
> +++ b/drivers/media/platform/qcom/iris/iris_ctrls.c
> @@ -1548,6 +1548,7 @@ int iris_set_slice_count(struct iris_inst *inst, enum platform_inst_fw_cap_type
>   	u32 mbpf = NUM_MBS_PER_FRAME(output_height, output_width);
>   	u32 max_width, max_height, min_width, min_height;
>   	u32 slice_mode = inst->fw_caps[cap_id].value;
> +	u32 bitrate = inst->fw_caps[BITRATE].value;
>   	u32 max_avg_slicesize, hfi_value, hfi_id;
>   	u32 rc_type = inst->hfi_rc_type;
>   	u32 fps = inst->frame_rate;
> @@ -1588,7 +1589,7 @@ int iris_set_slice_count(struct iris_inst *inst, enum platform_inst_fw_cap_type
>   	} else if (slice_mode == V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES) {
>   		hfi_value = inst->fw_caps[SLICE_MAX_BYTES].value;
>   		if (rc_type != HFI_RC_OFF) {
> -			max_avg_slicesize = DIV_ROUND_UP((inst->fw_caps[BITRATE].value / fps) / 8,
> +			max_avg_slicesize = DIV_ROUND_UP((bitrate / fps) / 8,
>   							 slice_caps->max_slices_per_frame);
>   		} else {
>   			/*
> 
> ---
> base-commit: 9abcab03dbf81439e18d09f1f3869bc39290ce4d
> change-id: 20261002-iris-fix-divdi3-44b1974118d8
> 
> Best regards,
> --
> Sachin Kumar Garg <sachin.garg@oss.qualcomm.com>
> 

20261001004619.2230849-1-sashal@kernel.org

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bod