de2563bce7
Turning on CONFIG_DMA_API_DEBUG_SG results in the following error: [ 460.308650] ------------[ cut here ]------------ [ 460.313490] qcom-venus aa00000.video-codec: DMA-API: mapping sg segment longer than device claims to support [len=4194304] [max=65536] [ 460.326017] WARNING: CPU: 3 PID: 3555 at src/kernel/dma/debug.c:1301 debug_dma_map_sg+0x174/0x254 [ 460.338888] Modules linked in: venus_dec venus_enc videobuf2_dma_sg videobuf2_memops hci_uart btqca bluetooth venus_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common ath10k_snoc ath10k_core ath lzo lzo_compress zramjoydev [ 460.375811] CPU: 3 PID: 3555 Comm: V4L2DecoderThre Tainted: G W 4.19.1 #82 [ 460.384223] Hardware name: Google Cheza (rev1) (DT) [ 460.389251] pstate: 60400009 (nZCv daif +PAN -UAO) [ 460.394191] pc : debug_dma_map_sg+0x174/0x254 [ 460.398680] lr : debug_dma_map_sg+0x174/0x254 [ 460.403162] sp : ffffff80200c37d0 [ 460.406583] x29: ffffff80200c3830 x28: 0000000000010000 [ 460.412056] x27: 00000000ffffffff x26: ffffffc0f785ea80 [ 460.417532] x25: 0000000000000000 x24: ffffffc0f4ea1290 [ 460.423001] x23: ffffffc09e700300 x22: ffffffc0f4ea1290 [ 460.428470] x21: ffffff8009037000 x20: 0000000000000001 [ 460.433936] x19: ffffff80091b0000 x18: 0000000000000000 [ 460.439411] x17: 0000000000000000 x16: 000000000000f251 [ 460.444885] x15: 0000000000000006 x14: 0720072007200720 [ 460.450354] x13: ffffff800af536e0 x12: 0000000000000000 [ 460.455822] x11: 0000000000000000 x10: 0000000000000000 [ 460.461288] x9 : 537944d9c6c48d00 x8 : 537944d9c6c48d00 [ 460.466758] x7 : 0000000000000000 x6 : ffffffc0f8d98f80 [ 460.472230] x5 : 0000000000000000 x4 : 0000000000000000 [ 460.477703] x3 : 000000000000008a x2 : ffffffc0fdb13948 [ 460.483170] x1 : ffffffc0fdb0b0b0 x0 : 000000000000007a [ 460.488640] Call trace: [ 460.491165] debug_dma_map_sg+0x174/0x254 [ 460.495307] vb2_dma_sg_alloc+0x260/0x2dc [videobuf2_dma_sg] [ 460.501150] __vb2_queue_alloc+0x164/0x374 [videobuf2_common] [ 460.507076] vb2_core_reqbufs+0xfc/0x23c [videobuf2_common] [ 460.512815] vb2_reqbufs+0x44/0x5c [videobuf2_v4l2] [ 460.517853] v4l2_m2m_reqbufs+0x44/0x78 [v4l2_mem2mem] [ 460.523144] v4l2_m2m_ioctl_reqbufs+0x1c/0x28 [v4l2_mem2mem] [ 460.528976] v4l_reqbufs+0x30/0x40 [ 460.532480] __video_do_ioctl+0x36c/0x454 [ 460.536610] video_usercopy+0x25c/0x51c [ 460.540572] video_ioctl2+0x38/0x48 [ 460.544176] v4l2_ioctl+0x60/0x74 [ 460.547602] do_video_ioctl+0x948/0x3520 [ 460.551648] v4l2_compat_ioctl32+0x60/0x98 [ 460.555872] __arm64_compat_sys_ioctl+0x134/0x20c [ 460.560718] el0_svc_common+0x9c/0xe4 [ 460.564498] el0_svc_compat_handler+0x2c/0x38 [ 460.568982] el0_svc_compat+0x8/0x18 [ 460.572672] ---[ end trace ce209b87b2f3af88 ]--- >From above warning one would deduce that the sg segment will overflow the device's capacity. In reality, the hardware can accommodate larger sg segments. So, initialize the max segment size properly to weed out this warning. Based on a similar patch sent by Sean Paul for mdss: https://patchwork.kernel.org/patch/10671457/ Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org> Acked-by: Stanimir Varbanov <stanimir.varbanov@linaro.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> |
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README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.