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. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
