On Fri, Oct 4, 2019 at 11:51 AM Adam Ford <aford...@gmail.com> wrote: > > On Fri, Oct 4, 2019 at 9:08 AM Adam Ford <aford...@gmail.com> wrote: > > > > On Fri, Oct 4, 2019 at 7:27 AM Yegor Yefremov > > <yegorsli...@googlemail.com> wrote: > > > > > > Hi Adam, > > > > > > On Fri, Oct 4, 2019 at 12:39 PM Adam Ford <aford...@gmail.com> wrote: > > > > > > > > On Fri, Oct 4, 2019 at 5:02 AM Adam Ford <aford...@gmail.com> wrote: > > > > > > > > > > I am running Kernel 5.3.2 trying to troubleshoot some intermittent > > > > > Bluetooth issues, and I think I have narrowed it down to the serial > > > > > driver in use. > > > > > > > > I should have also noted that it's using UART2 with CTS and RTS on the > > > > DM3730 (omap3630) and its configured with a baud rate of 3M. > > > > I tried slowing it to 115200, but that didn't help. I tried disabling > > > > the DMA hooks from the device tree, and that didn't help. > > > > > > > > > By default, omap2plus_defconfig enables both SERIAL_8250_OMAP and > > > > > SERIAL_OMAP. I have my console device configured as ttyS0, and all > > > > > appears fine. When I enable Bluetooth, however, I get intermittent > > > > > errors on an DM3730 / OMAP3630. > > > > > > > > > > Using the 8250 driver for Blueotooth I get intermittent frame errors > > > > > and data loss. > > > > > > > > > > Scanning ... > > > > > [ 28.482452] Bluetooth: hci0: Frame reassembly failed (-84) > > > > > [ 36.162170] Bluetooth: hci0: Frame reassembly failed (-84) > > > > > F4:4E:FC:C9:2F:57 BluJax > > > > > # l2ping F4:4E:FC:C9:2F:57 > > > > > Ping: F4:4E:FC:C9:2F:57 from 00:18:30:49:7D:63 (data size 44) ... > > > > > 44 bytes from F4:4E:FC:C9:2F:57 id 0 time 8.27ms > > > > > no response from F4:4E:FC:C9:2F:57: id 1 > > > > > ^C2 sent, 1 received, 50% loss > > > > > > > > > > (after a fairly long hang, I hit control-c) > > > > > > > > > > However, disabling the 8250 driver and using the only SERIAL_OMAP and > > > > > the console routed to ttyO0, the Bluetooth works well, so I believe it > > > > > to be a serial driver issue and not a Bluetooth error. > > > > > > > > > > # hcitool scan > > > > > Scanning ... > > > > > F4:4E:FC:C9:2F:57 BluJax > > > > > ^C > > > > > # l2ping F4:4E:FC:C9:2F:57 > > > > > Ping: F4:4E:FC:C9:2F:57 from 00:18:30:49:7D:63 (data size 44) ... > > > > > 44 bytes from F4:4E:FC:C9:2F:57 id 0 time 6.90ms > > > > > ... > > > > > 44 bytes from F4:4E:FC:C9:2F:57 id 14 time 28.29ms > > > > > ^C15 sent, 15 received, 0% loss > > > > > # > > > > > > > > > > 0% loss and regular, repeatable communication without any Frame > > > > > reassembly errors. > > > > > > > > > > > > > I tried disabling SERIAL_OMAP and using only SERIAL_8250_OMAP, but > > > > that didn't help. Because the issue goes away when I disable > > > > SERIAL_8250_OMAP, I am wondering if something is either being > > > > misconfigured or some IRQ or DMA integration is missing that may be > > > > present with the older SERIAL_OMAP driver. > > > > > > > > > Any suggestions on how to troubleshoot or what might cause the > > > > > difference between the two drivers? > > > > > > Can it be related to this issue [1]? Can you confirm that 5.2 is > > > working as expected with the 8250 driver? > > > > > > [1] https://marc.info/?l=linux-serial&m=156965039008649&w=2 > > > > I reverted the whole 8250 directory to d99482673f95 ("serial: > > mctrl_gpio: Check if GPIO property exisits before requesting it") and > > it is somewhat better, but it's not as good as the stock OMAP serial > > driver. I get some frame errors and eventually, I get some timeouts, > > but it's not as bad. I'll try to implement the RTS and CTS as gpio > > pins and change the device tree accordingly. It might shed some light > > on the situation. > > I tried to manually setup RTS and CTS pins as GPIO, but that didn't > work, so I changed it back. > > It looks like the clocking is correct. I don't know enough about the > DMA or the IRQ to know if it's working correctly. > > I was wondering if the problem is in the handshaking or not. > I added " uart-has-rtscts;" to by uart node thinking it might help, > but it did not. > > > > 8250_omap.c has some checks to see if we can enable autoRTS: > > if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW && > !up->gpios) { > /* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */ > ... > } > > Based on this, I would expect up->gpios to always be zero if we want > auto RTS CTS. > > I threw some debug code into the serial driver to look at the status > of the various flags that go into setting up auto RTS/CTS. > > [ 13.837005] termios->c_cflag & CRTSCTS = 80000000 > [ 13.841888] up->port.flags & UPF_HARD_FLOW = 300000 > [ 13.846801] up->gpios = ce3f3cc0 > [ 17.166595] termios->c_cflag & CRTSCTS = 0 > [ 17.170745] up->port.flags & UPF_HARD_FLOW = 300000 > [ 17.175781] up->gpios = ce3f3d40 > > I don't know which port is which, but I only have two active uarts > (console and Bluetooth) > The Bluetooth port should use handshaking and the console should not. > > From the look of the dump, up->gpios is never 0, so the last > evaluation would always be false unless I am misinterpreting > something. > > I tried to modify the check to remove !up->gpios check, but that > didn't help either, but it made it a little better.
I have it working now on the 5.3.y branch, but I had to do 4 things. 1) Disable the older OMAP serial driver 2) Apply [1] patch 3) Disable 8250 DMA support 4) Remove checks for !up->gpios in the 8250-omap.c code. With all those changes, I am able to successfully and repeatedly scan and l2ping Bluetooth devices. Without any one of those, I get frame errors or lost packets. I wonder if we can dump the legacy omap serial driver once the 8250 driver is working better. That would eliminate at least one of the 4. I am not sure what's up with the DMA, and I've already stated some thoughts on item 4 in a previous e-mail. I think the [1] patch is probably going to help fix some other issues and should probably be backported, but by itself it isn't enough to fix the Bluetooth problem on the OMAP3630. [1] - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/tty/serial/8250/8250_omap.c?h=v5.4-rc1&id=627a545c6bb0c7de09208e6546f5111290477261 adam > > > > adam > > > > > > Cheers, > > > Yegor
