On Wed, Dec 27, 2023 at 10:10 AM bumyong.lee <bumyong.lee@xxxxxxxxxxx> wrote: > > Hello. > > > On Thu, Dec 21, 2023 at 10:00:26PM +0530, Vinod Koul wrote: > > > > This seems to cause a stall on my Quartz 64 model B (RK3566) once > > Bluetooth over UART is initialized, when combined with a patch of mine > > that enables DMA on UARTs [1]. Reverting this patch gets everything > > running again. > > > > The following are RCU stalls detected, followed by stack traces produced > > with pseudo-NMI. Without pseudo-NMIs no stack traces are produced. > > > > rcu: INFO: rcu_sched detected stalls on CPUs/tasks: > > rcu: 0-...0: (0 ticks this GP) idle=80fc/1/0x4000000000000000 > > softirq=693/693 fqs=31498 > > rcu: 3-...0: (3 ticks this GP) idle=2b44/1/0x4000000000000000 > > softirq=553/556 fqs=31498 > > rcu: (detected by 1, t=162830 jiffies, g=-307, q=32 ncpus=4) > > Sending NMI from CPU 1 to CPUs 0: > > NMI backtrace for cpu 0 > > CPU: 0 PID: 1200 Comm: (udev-worker) Not tainted 6.7.0-rc6-next- > > 20231222-10300-g8b07e3811bc7 #17 > > Hardware name: Pine64 RK3566 Quartz64-B Board (DT) > > pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > pc : queued_spin_lock_slowpath+0x50/0x330 > > lr : pl330_irq_handler+0x2f8/0x5a0 > > sp : ffffffc080003ec0 > > pmr_save: 00000060 > > x29: ffffffc080003ec0 x28: ffffff80017c7000 x27: ffffff8001a58d80 > > x26: 0000000000000060 x25: ffffff80017d0338 x24: ffffff800161ae38 > > x23: ffffff8001597c00 x22: ffffffc081960000 x21: 0000000000000000 > > x20: ffffff800161ac80 x19: ffffff80010c5180 x18: 0000000000000000 > > x17: ffffffc06e724000 x16: ffffffc080000000 x15: 0000000000000000 > > x14: 0000000000000000 x13: ffffff80042f102f x12: ffffffc083ad3cc4 > > x11: 0000000000000040 x10: ffffff800022a0a8 x9 : ffffff800022a0a0 > > x8 : ffffff8000400270 x7 : 0000000000000000 x6 : 0000000000000000 > > x5 : ffffff8000400248 x4 : ffffffc06e724000 x3 : ffffffc080003fa0 > > x2 : 0000000000000000 x1 : 0000000000000001 x0 : ffffff800161ae38 > > Call trace: > > queued_spin_lock_slowpath+0x50/0x330 > > __handle_irq_event_percpu+0x38/0x16c > > handle_irq_event+0x44/0xf8 > > handle_fasteoi_irq+0xb0/0x28c > > generic_handle_domain_irq+0x2c/0x44 > > gic_handle_irq+0x10c/0x240 > > call_on_irq_stack+0x24/0x4c > > do_interrupt_handler+0x80/0x8c > > el1_interrupt+0x44/0x98 > > el1h_64_irq_handler+0x18/0x24 > > el1h_64_irq+0x78/0x7c > > __d_rehash+0x0/0x94 > > d_add+0x40/0x80 > > simple_lookup+0x4c/0x78 > > path_openat+0x5ec/0xed0 > > do_filp_open+0x80/0x12c > > do_sys_openat2+0xb4/0xe8 > > __arm64_sys_openat+0x64/0xa4 > > invoke_syscall+0x48/0x114 > > el0_svc_common.constprop.0+0x40/0xe0 > > do_el0_svc+0x1c/0x28 > > el0_svc+0x34/0xd4 > > el0t_64_sync_handler+0x100/0x12c > > el0t_64_sync+0x1a4/0x1a8 > > Sending NMI from CPU 1 to CPUs 3: > > NMI backtrace for cpu 3 > > CPU: 3 PID: 31 Comm: kworker/3:0 Not tainted 6.7.0-rc6-next-20231222- > > 10300-g8b07e3811bc7 #17 > > Hardware name: Pine64 RK3566 Quartz64-B Board (DT) > > Workqueue: events hci_uart_write_work [hci_uart] > > pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > pc : _state+0x2c/0x138 > > lr : pl330_start_thread.isra.0+0x2e0/0x32c > > sp : ffffffc08157bb20 > > pmr_save: 00000060 > > x29: ffffffc08157bb20 x28: 0000000000000000 x27: 0000000000000060 > > x26: ffffffc080c4e658 x25: 0000000000000060 x24: 0000000001a20000 > > x23: ffffff8001555000 x22: ffffffc081960020 x21: ffffff800161b068 > > x20: 0000000000000000 x19: ffffff800161b050 x18: ffffffffffffffff > > x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001 > > x14: 0000000000000004 x13: 0000000000000009 x12: 0000000000000005 > > x11: 0000000000000027 x10: 000000000000002b x9 : 0000000000000032 > > x8 : ffffffc08154521d x7 : 0000000000000005 x6 : 0000000000000010 > > x5 : 0000000000000001 x4 : ffffffc081960d04 x3 : ffffff800161b280 > > x2 : ffffff800161b050 x1 : 0000000000204000 x0 : 0000000000000108 > > Call trace: > > _state+0x2c/0x138 > > pl330_tasklet+0x1f8/0x818 > > pl330_issue_pending+0x150/0x178 > > serial8250_tx_dma+0x150/0x21c > > serial8250_start_tx+0x9c/0x1c0 > > __uart_start+0x74/0xfc > > uart_write+0xfc/0x2f0 > > ttyport_write_buf+0x4c/0x90 > > serdev_device_write_buf+0x24/0x38 > > hci_uart_write_work+0x54/0x164 [hci_uart] > > process_one_work+0x13c/0x2bc > > worker_thread+0x2a0/0x52c > > kthread+0xe0/0xe4 > > ret_from_fork+0x10/0x20 > I think the dma channel already passed WFP state. > > The errata[1] says that > 4. The driver polls the status of channel 0 until it observes that > it has entered the "Waiting for peripheral" state > 5. The driver enables the peripheral to allow it to issue DMA requests > > When I review 8250_dma.c, I think serial8250_do_prepare_tx_dma() of > serial8250_tx_dma() would enable peripheral to allow issue DMA requests. > serial8250_do_prepare_tx_dma(p) performs before dma_async_issue_pending() > It means that serial8250_tx_dma() has reversed sequence step 4 and 5 for > pl330. serial8250_prepare_tx_dma() on Rockchip doesn't do anything. The callback called in serial8250_prepare_tx_dma() simply isn't set. For this hardware the DMA request will be asserted when the TX FIFO is empty, or when the RX FIFO has data, depending on the direction. >From the DesignWare UART release notes: In mode 0 (single shot DMA), the dma_tx_req_n signal goes active low under the following conditions: - When the Transmitter Holding Register is empty in non-FIFO mode - When the transmitter FIFO is empty in FIFO mode with Programmable THRE interrupt mode disabled - When the transmitter FIFO is at or below the programmed threshold with Programmable THRE interrupt mode enabled Mode 1 (continuous DMA) is the same, minus the first condition. > But I'm not sure if the errata suggests normal slave driver dma usage > sequence or not. I'm not sure what you mean by this. > If it is abnormal sequence, I think it should be handled by quirk A quirk on which device? The DMA controller? ChenYu > [1]: https://developer.arm.com/documentation/genc008428/latest >
