On Fri, Oct 4, 2019 at 10:45 PM Adam Ford <aford173@xxxxxxxxx> wrote: > > On Fri, Oct 4, 2019 at 11:51 AM Adam Ford <aford173@xxxxxxxxx> wrote: > > > > On Fri, Oct 4, 2019 at 9:08 AM Adam Ford <aford173@xxxxxxxxx> wrote: > > > > > > On Fri, Oct 4, 2019 at 7:27 AM Yegor Yefremov > > > <yegorslists@xxxxxxxxxxxxxx> wrote: > > > > > > > > Hi Adam, > > > > > > > > On Fri, Oct 4, 2019 at 12:39 PM Adam Ford <aford173@xxxxxxxxx> wrote: > > > > > > > > > > On Fri, Oct 4, 2019 at 5:02 AM Adam Ford <aford173@xxxxxxxxx> 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 > In the latest 'master' branch of 5.4-RC1 (43b815c6a8e7), I have confirmed that by removing the DMA and forcing the checks for !up->gpios to be true to keep the hardware flow control working, I can repeatably make Bluetooth work. I am not sure what's broken in the DMA, but the check for !up->gpios is never false, so it never actually does the code inside to address handshaking index c68e2b3a1634..884fcba61303 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -141,7 +141,7 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) serial8250_do_set_mctrl(port, mctrl); - if (!up->gpios) { + if (1 /* !up->gpios */) { /* * Turn off autoRTS if RTS is lowered and restore autoRTS * setting if RTS is raised @@ -455,8 +455,7 @@ static void omap_8250_set_termios(struct uart_port *port, priv->efr = 0; up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF); - if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW && - !up->gpios) { + if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) { /* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */ up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS; priv->efr |= UART_EFR_CTS; I know this is wrong to do what I did, but whatever is setting gpios is clearly not setting it to NULL, so I am guessing these checks here to be something else or something needs to be able to set these to NULL when there are no manually configured gpio pints for cts/rts. adam > adam > > > > > > > adam > > > > > > > > Cheers, > > > > Yegor
