Re: [PATCH v8 02/18] media: iris: Skip UBWC configuration when not supported

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] UBWC system initialization is skipped on unsupported platforms, but UBWC V4L2 pixel formats are still unconditionally exposed and accepted, leading to invalid session configurations.
--

--- Patch [2]: [PATCH v8 02/18] media: iris: Skip UBWC configuration when not supported ---
commit 2c20085257ddd4d7a77928a6e07815a827326525
Author: Dikshita Agarwal <dikshita.agarwal@oss.qualcomm.com>

media: iris: Skip UBWC configuration when not supported

This commit skips Universal Bandwidth Compression (UBWC) configuration
during system initialization on unsupported platforms. It achieves this
by checking if the UBWC encoder version is non-zero before sending UBWC
properties to the firmware.

> diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2_packet.c b/drivers/media/platform/qcom/iris/iris_hfi_gen2_packet.c
> index 0d05dd2afc07d..6e04175eb904b 100644
> --- a/drivers/media/platform/qcom/iris/iris_hfi_gen2_packet.c
> +++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2_packet.c
> @@ -140,6 +140,9 @@ void iris_hfi_gen2_packet_sys_init(struct iris_core *core, struct iris_hfi_heade
>  				    &payload,
>  				    sizeof(u32));
>  
> +	if (!ubwc->ubwc_enc_version)
> +		return;
> +

[Severity: High]
This is a pre-existing issue, but while this patch prevents UBWC system
initialization on unsupported SoCs, are UBWC V4L2 pixel formats still
unconditionally exposed and accepted by the driver?

In drivers/media/platform/qcom/iris/iris_vdec.c:check_format(), the requested
format is validated against a static array without checking for UBWC support:

    case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
        fmt = iris_vdec_formats_cap;
        size = ARRAY_SIZE(iris_vdec_formats_cap);
        break;

If userspace selects a UBWC format (like V4L2_PIX_FMT_QC08C) on an unsupported
SoC, it appears drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c:
iris_hfi_gen2_set_colorformat() will still send UBWC session properties to the
firmware:

        switch (pixelformat) {
        ...
        case V4L2_PIX_FMT_QC08C:
            hfi_colorformat = HFI_COLOR_FMT_NV12_UBWC;
            break;

Since system-level UBWC configuration is now skipped, will sending these UBWC
session properties cause firmware errors or stream failures? Should the driver
also filter out UBWC formats during enumeration and validation on these
platforms?

>  	payload = qcom_ubwc_macrotile_mode(ubwc) ? 8 : 4;
>  	iris_hfi_gen2_create_packet(hdr,
>  				    HFI_PROP_UBWC_MAX_CHANNELS,

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260730-iris-ar50lt-v8-0-6597c08cea6f@oss.qualcomm.com?part=2