> On Sat, Feb 09, 2019 at 09:29:05PM +0100, Stefan Wahren wrote: > > > could you please test the following series: > > > https://patchwork.kernel.org/cover/10764453/ > > > > yeah this fixed the probing timeout and the driver will probe successful. AFAIK the dwc2 host mode doesn't support scatter-gather yet. > > So this is either dwc2 scatter-gather problem which should be addressed in > this driver or mt76x0u does something wrong when configuring SG. > > Disabling SG is just workaround, which do not address actual problem. > > I think I found mt76x0u issue that could cause this USB probe error > (and possibly also address AMD IOMMU issue). We seems do not correctly > set URB transfer length smaller than sg buffer length. Attached patch > should correct that. Hi Stanislaw, I think 'sg[0].length' is already set in mt76u_fill_rx_sg(). Moreover applying this patch I got the following crash (rpi-5.0.y): [ 38.856623] mt76x0u 1-1.2:1.0: ASIC revision: 76100002 MAC revision: 76502000 [ 38.865999] ------------[ cut here ]------------ [ 38.871817] WARNING: CPU: 3 PID: 751 at lib/refcount.c:187 refcount_sub_and_test_checked+0xa4/0xb8 [ 38.883277] refcount_t: underflow; use-after-free. [ 38.889358] Modules linked in: mt76x0u(+) mt76x0_common mt76x02_usb mt76_usb mt76x02_lib mt76 mac80211 bnep hci_uart btbcm serdev bluetooth ecdh_generic spidev brcmfmac brcmutil sha256_generic cfg80211 rfkill raspberrypi_hwmon hwmon b cm2835_v4l2(C) i2c_bcm2835 v4l2_common videobuf2_vmalloc videobuf2_memops snd_bcm2835(C) spi_bcm2835 videobuf2_v4l2 videobuf2_common snd_pcm videodev snd_timer media snd uio_pdrv_genirq uio fixed i2c_dev ip_tables x_tables ipv6 [ 38.938953] CPU: 3 PID: 751 Comm: systemd-udevd Tainted: G C 5.0.0-rc5-v7+ #1 [ 38.950574] Hardware name: BCM2835 [ 38.955503] Backtrace: [ 38.959410] [<8010c91c>] (dump_backtrace) from [<8010cc00>] (show_stack+0x20/0x24) [ 38.969952] r6:60000013 r5:ffffffff r4:00000000 r3:a50bade6 [ 38.977198] [<8010cbe0>] (show_stack) from [<807ca5f4>] (dump_stack+0xc8/0x114) [ 38.986183] [<807ca52c>] (dump_stack) from [<8011e65c>] (__warn+0xf4/0x120) [ 38.994804] r9:000000bb r8:804d0138 r7:00000009 r6:8099dc84 r5:00000000 r4:b9631b58 [ 39.005708] [<8011e568>] (__warn) from [<8011e6d0>] (warn_slowpath_fmt+0x48/0x50) [ 39.016372] r9:7f652128 r8:80d1419c r7:80c0bac4 r6:b34a2044 r5:b6096780 r4:00000000 [ 39.027368] [<8011e68c>] (warn_slowpath_fmt) from [<804d0138>] (refcount_sub_and_test_checked+0xa4/0xb8) [ 39.040150] r3:80c91c25 r2:8099dc94 [ 39.045296] r4:00000000 [ 39.049320] [<804d0094>] (refcount_sub_and_test_checked) from [<804d0164>] (refcount_dec_and_test_checked+0x18/0x1c) [ 39.062966] r4:b6096780 r3:00000001 [ 39.068043] [<804d014c>] (refcount_dec_and_test_checked) from [<805db49c>] (usb_free_urb+0x20/0x4c) [ 39.080279] [<805db47c>] (usb_free_urb) from [<7f62d804>] (mt76u_buf_free+0x98/0xac [mt76_usb]) [ 39.092224] r4:00000001 r3:00000001 [ 39.097386] [<7f62d76c>] (mt76u_buf_free [mt76_usb]) from [<7f62def8>] (mt76u_queues_deinit+0x44/0x100 [mt76_usb]) [ 39.111016] r8:b791f600 r7:b3628480 r6:b3628e20 r5:00000001 r4:00000000 r3:00000080 [ 39.122039] [<7f62deb4>] (mt76u_queues_deinit [mt76_usb]) from [<7f650040>] (mt76x0u_cleanup+0x40/0x4c [mt76x0u]) [ 39.135636] r7:b3628480 r6:b791f600 r5:ffffffea r4:b3628e20 [ 39.142968] [<7f650000>] (mt76x0u_cleanup [mt76x0u]) from [<7f650564>] (mt76x0u_probe+0x1f0/0x354 [mt76x0u]) [ 39.156063] r4:b3628e20 r3:00000000 [ 39.161202] [<7f650374>] (mt76x0u_probe [mt76x0u]) from [<805e0b6c>] (usb_probe_interface+0x104/0x240) [ 39.173805] r7:00000000 r6:7f652034 r5:b6299000 r4:b791f620 [ 39.181165] [<805e0a68>] (usb_probe_interface) from [<8056a8bc>] (really_probe+0x224/0x2f8) [ 39.192856] r10:b626d800 r9:00000019 r8:7f652034 r7:80d3e124 r6:00000000 r5:80d3e120 [ 39.204057] r4:b791f620 r3:805e0a68 [ 39.209269] [<8056a698>] (really_probe) from [<8056ab60>] (driver_probe_device+0x6c/0x180) [ 39.220854] r10:b626d800 r9:7f6522c0 r8:b791f620 r7:00000000 r6:7f652034 r5:7f652034 [ 39.232057] r4:b791f620 r3:00000000 [ 39.237265] [<8056aaf4>] (driver_probe_device) from [<8056ad54>] (__driver_attach+0xe0/0xe4) [ 39.248982] r9:7f6522c0 r8:7f65122c r7:00000000 r6:b791f654 r5:7f652034 r4:b791f620 [ 39.260002] [<8056ac74>] (__driver_attach) from [<8056880c>] (bus_for_each_dev+0x68/0xa0) [ 39.271498] r6:8056ac74 r5:7f652034 r4:00000000 r3:00000027 [ 39.278885] [<805687a4>] (bus_for_each_dev) from [<8056a1cc>] (driver_attach+0x28/0x30) [ 39.290252] r6:80c6ddc8 r5:b6096a00 r4:7f652034 [ 39.296557] [<8056a1a4>] (driver_attach) from [<80569c24>] (bus_add_driver+0x194/0x21c) [ 39.307899] [<80569a90>] (bus_add_driver) from [<8056b504>] (driver_register+0x8c/0x124) [ 39.319328] r7:80c6ddc8 r6:7f652034 r5:00000000 r4:7f652034 [ 39.326730] [<8056b478>] (driver_register) from [<805df510>] (usb_register_driver+0x74/0x140) [ 39.338655] r5:00000000 r4:7f652000 [ 39.343880] [<805df49c>] (usb_register_driver) from [<7f655024>] (mt76x0_driver_init+0x24/0x1000 [mt76x0u]) [ 39.357002] r9:00000001 r8:7f652308 r7:00000000 r6:80c08d48 r5:7f655000 r4:7f6522c0 [ 39.368143] [<7f655000>] (mt76x0_driver_init [mt76x0u]) from [<80102f6c>] (do_one_initcall+0x4c/0x210) [ 39.380894] [<80102f20>] (do_one_initcall) from [<801ae63c>] (do_init_module+0x6c/0x21c) [ 39.392392] r8:7f652308 r7:80c08d48 r6:b6116880 r5:7f6522c0 r4:7f6522c0 [ 39.400876] [<801ae5d0>] (do_init_module) from [<801ad68c>] (load_module+0x1d10/0x2304) Moreover for mt76x0u SG is 'already' disabled since we use just one buffer so from performance point of view I do not see any difference of using a standard usb buffer. This patch has been tested in multiple scenarios and seems to fix reported issues (for usb2.0). Are you concerned about increasing code complexity? Regards, Lorenzo > > Stanislaw
