Hi Hans, On Wed, 2016-05-04 at 10:25 +0200, Hans Verkuil wrote: > > On 05/04/2016 10:19 AM, tiffany lin wrote: > > Hi Hans, > > > > On Wed, 2016-05-04 at 09:32 +0200, Hans Verkuil wrote: > >> Hi Tiffany, > >> > >> On 05/03/2016 12:11 PM, Tiffany Lin wrote: > >>> ============== > >>> Introduction > >>> ============== > >>> > >>> The purpose of this series is to add the driver for video codec hw > >>> embedded in the Mediatek's MT8173 SoCs. > >>> Mediatek Video Codec is able to handle video encoding of in a range of > >>> formats. > >>> > >>> This patch series also include VPU driver. Mediatek Video Codec driver > >>> rely on VPU driver to load, > >>> communicate with VPU. > >>> > >>> Internally the driver uses videobuf2 framework and MTK IOMMU and MTK SMI > >>> both have been merged in v4.6-rc1. > >>> This patch series need [PATCH v15 8/8] memory: mtk-smi: export > >>> mtk_smi_larb_get/put[1] to build as module > >>> > >>> [1]http://lists.infradead.org/pipermail/linux-mediatek/2016-April/005173.html > >>> > >>> ================== > >>> Device interface > >>> ================== > >>> > >>> In principle the driver bases on v4l2 memory-to-memory framework: > >>> it provides a single video node and each opened file handle gets its own > >>> private context with separate > >>> buffer queues. Each context consist of 2 buffer queues: OUTPUT (for > >>> source buffers, i.e. raw video > >>> frames) and CAPTURE (for destination buffers, i.e. encoded video frames). > >>> > >>> ============================== > >>> VPU (Video Processor Unit) > >>> ============================== > >>> The VPU driver for hw video codec embedded in Mediatek's MT8173 SOCs. > >>> It is able to handle video decoding/encoding in a range of formats. > >>> The driver provides with VPU firmware download, memory management and the > >>> communication interface between CPU and VPU. > >>> For VPU initialization, it will create virtual memory for CPU access and > >>> physical address for VPU hw device access. > >>> When a decode/encode instance opens a device node, vpu driver will > >>> download vpu firmware to the device. > >>> A decode/encode instant will decode/encode a frame using VPU interface to > >>> interrupt vpu to handle decoding/encoding jobs. > >>> > >>> Please have a look at the code and comments will be very much appreciated. > >>> > >>> Change in v10: > >>> 1. Fix smatch/sparse error message > >>> 2. Add depends on ARM || ARM64 and MTK_IOMMU in Kconfig > >> > >> I don't like the ARM or ARM64 dependency since that makes COMPILE_TEST > >> harder. > >> > >> I removed it here and for the VPU and everything still compiles fine with > >> sparse and smatch. So I'll drop those dependencies. > >> > >> Why is the MTK_IOMMU dependency needed? Just curious. > >> > > This is because we need MTK_IOMMU module to get dma continuous memory > > for HW. > > > >> Note that sparse still complains about this: > >> > >> media-git/drivers/media/platform/mtk-vcodec/venc/venc_vp8_if.c:261:24: > >> warning: incorrect type in assignment (different base types) > >> > >> I think this code should be rewritten. Something like this would work > >> (if I understand the code correctly): > >> > >> u32 tag = (bs_hdr_len << 5) | 0x10 | not_key; > >> > >> ac_tag[0] = tag & 0xff; > >> ac_tag[1] = (tag >> 8) & 0xff; > >> ac_tag[2] = (tag >> 16) & 0xff; > >> > >> It's perhaps a bit more verbose, but a lot easier to understand. > >> > > > >> I'm accepting this driver but I'll remove the ARM || ARM64 dependency. Can > >> you post a follow-up patch for this sparse warning? > >> > > > > Got it. We will provide a patch to fix this. > > I was curious why my sparse do not show this warning. > > Is there any parameter I need to set except C=1? > > I'm running it with these parameters: C=2 CF="-D__CHECK_ENDIAN__" > > I suspect it is the CHECK_ENDIAN flag that does it. > Got it, thanks for the information.
best regards, Tiffany > Regards, > > Hans
