Hello again, On 21.01.2015 14:29, Hans Verkuil wrote: > On 01/21/15 14:28, Florian Echtler wrote: >> On 20.01.2015 14:06, Laurent Pinchart wrote: >>> That depends on the platform and whether it can DMA to vmalloc'ed memory :-) >>> To be totally safe I think vb2-dma-sg would be better, but I'm not sure it's >>> worth the trouble. uvcvideo uses vb2-vmalloc as it performs a memcpy anyway. >> The SUR40 sends raw video data without any headers over the bulk >> endpoint in blocks of 16k, so I'm assuming that in this specific case, >> vb2-dma-sg would be the most efficient choice? I'm still having a couple of issues sorting out the correct way to provide DMA access for my driver. I've integrated most of your suggestions, but I still can't switch from dma-contig to dma-sg. As far as I understood it, there is no further initialization required besides using vb2_dma_sg_memops, vb2_dma_sg_init_ctx and vb2_dma_sg_cleanup_ctx instead of the respective -contig- calls, correct? However, as soon as I swap the relevant function calls, the video image stays black and in dmesg, I get the following warning: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 37 at /home/kernel/COD/linux/drivers/usb/core/hcd.c:1504 usb_hcd_map_urb_for_dma+0x4eb/0x500() transfer buffer not dma capable Modules linked in: sur40(OE) videobuf2_dma_contig videobuf2_dma_sg videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common videodev media dm_crypt joydev input_polldev wl(POE) snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi cfg80211 kvm_amd snd_seq kvm edac_core serio_raw snd_seq_device btusb snd_timer edac_mce_amd snd ipmi_si ipmi_msghandler k10temp sp5100_tco i2c_piix4 soundcore bnep 8250_fintek shpchp tpm_infineon rfcomm bluetooth mac_hid parport_pc ppdev lp parport hid_apple usbhid hid pata_acpi uas usb_storage amdkfd amd_iommu_v2 radeon psmouse pata_atiixp i2c_algo_bit ttm drm_kms_helper drm ahci libahci r8169 mii [last unloaded: sur40] CPU: 1 PID: 37 Comm: kworker/1:1 Tainted: P OE 3.19.0-031900rc6-generic #201501261152 Hardware name: Samsung SUR40/SDNE-R78BA2-20, BIOS SDNE-R78BA2-2000 11/04/2011 Workqueue: events_freezable input_polled_device_work [input_polldev] 00000000000005e0 ffff8801320c3aa8 ffffffff817c4584 0000000000000007 ffff8801320c3af8 ffff8801320c3ae8 ffffffff81076df7 0000000000000000 ffff8800a71fa6c0 ffff88013243f800 0000000000000010 0000000000000002 Call Trace: [<ffffffff817c4584>] dump_stack+0x45/0x57 [<ffffffff81076df7>] warn_slowpath_common+0x97/0xe0 [<ffffffff81076ef6>] warn_slowpath_fmt+0x46/0x50 [<ffffffff815aff0b>] usb_hcd_map_urb_for_dma+0x4eb/0x500 [<ffffffff817d03b4>] ? schedule_timeout+0x124/0x210 [<ffffffff815b0bd5>] usb_hcd_submit_urb+0x135/0x1c0 [<ffffffff815b20a6>] usb_submit_urb.part.8+0x1f6/0x580 [<ffffffff811bb542>] ? vmap_pud_range+0x122/0x1c0 [<ffffffff815b2465>] usb_submit_urb+0x35/0x80 [<ffffffff815b339a>] usb_start_wait_urb+0x6a/0x170 [<ffffffff815b1cce>] ? usb_alloc_urb+0x1e/0x50 [<ffffffff815b1cce>] ? usb_alloc_urb+0x1e/0x50 [<ffffffff815b3570>] usb_bulk_msg+0xd0/0x1a0 [<ffffffffc059a841>] sur40_poll+0x561/0x5e0 [sur40] [<ffffffffc016134b>] input_polled_device_work+0x1b/0x30 [input_polldev] [<ffffffff8108f6dd>] process_one_work+0x14d/0x460 [<ffffffff810900bb>] worker_thread+0x11b/0x3f0 [<ffffffff8108ffa0>] ? create_worker+0x1e0/0x1e0 [<ffffffff81095cc9>] kthread+0xc9/0xe0 [<ffffffff81095c00>] ? flush_kthread_worker+0x90/0x90 [<ffffffff817d17fc>] ret_from_fork+0x7c/0xb0 [<ffffffff81095c00>] ? flush_kthread_worker+0x90/0x90 ---[ end trace 30eaf6524fd028d3 ]--- Moreover, I'm getting the following test failure from v4l2-compliance: Streaming ioctls: test read/write: OK test MMAP: OK fail: v4l2-test-buffers.cpp(951): buf.qbuf(node) fail: v4l2-test-buffers.cpp(994): setupUserPtr(node, q) test USERPTR: FAIL test DMABUF: Cannot test, specify --expbuf-device Total: 45, Succeeded: 44, Failed: 1, Warnings: 0 Any suggestions how to deal with this? Best regards, Florian -- SENT FROM MY DEC VT50 TERMINAL
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