Hi Brian, I've been working on a vhost-user frontend for virtio-media in libkrun[1] and tested this series with vhost-device-media[2]. A few things I noticed:
1. Wrong constant in vfl_dir detection in virtio_media_driver.c: > > + if (vd->device_caps & (V4L2_CAP_VIDEO_M2M | V4L2_CAP_VIDEO_M2M_MPLANE)) > + vd->vfl_dir = VFL_DIR_M2M; > + else if (vd->device_caps & > + (V4L2_CAP_VIDEO_OUTPUT | V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)) > + vd->vfl_dir = VFL_DIR_TX; V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE is a buffer type enum, not a capability flag. So it should be V4L2_CAP_VIDEO_OUTPUT_MPLANE. 2. Kconfig architecture support > + depends on VIRTIO && VIDEO_DEV && 64BIT && (X86 || (ARM && > CPU_LITTLE_ENDIAN)) ARM64 is missing here, so the driver cannot be selected on aarch64. Also, CONFIG_ARM is 32-bit only, so 64BIT && ARM can never be true; that branch is dead code. Since the driver has no platform specific code, this could just be: + depends on VIRTIO && VIDEO_DEV && 64BIT as it already covers x86_64, ARM64, and any other 64 bit architecture without listing them individually. 3. Error sign convention: > + resp_header = sg_virt(sgs[out_sgs]); > + if (resp_header->status) > + /* Host returns a positive error code. */ > + return -resp_header->status; The comment in the driver and the protocol spec contradict each other. The protocol.h describes the status field as "one of the standard Linux error codes" without specifying a sign. It's probably worth making the protocol spec explicit that the host returns positive error codes to match the driver's assumption. [1] https://github.com/libkrun/libkrun/pull/811 [2] https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-media BR, Dorinda.
