| Message ID | 20170315152948.10978-1-nicolas.ferre@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 15/03/2017 16:29, Nicolas Ferre wrote: > A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA > from transmitting in stop_tx") is that the console can be called with > TX path disabled. Then the system would hang trying to push charecters > out in atmel_console_putchar(). > > Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com> > Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting > in stop_tx") > Cc: stable <stable@vger.kernel.org> # 4.4+ > --- > Hi Richard, > > I found this to fix the problem with system hang in my linux-4.4-at91 branch > (in the atmel_console_putchar() waiting loop actually). I'm open to more > insignt. > As we cannot figure out if this bit is set or not, I didn't preserve the > current status... > > Regards, So, I'm guessing that you may see some lines/characters printed twice on the screen, don't you ? > drivers/tty/serial/atmel_serial.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > index dcebb28ffbc4..7372dbdb7a4c 100644 > --- a/drivers/tty/serial/atmel_serial.c > +++ b/drivers/tty/serial/atmel_serial.c > @@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) > pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN; > atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); > > + /* Make sure that tx path is actually able to send characters */ > + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); > + > uart_console_write(port, s, count, atmel_console_putchar); > > /* > Richard.
Le 15/03/2017 à 17:19, Richard Genoud a écrit : > On 15/03/2017 16:29, Nicolas Ferre wrote: >> A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA >> from transmitting in stop_tx") is that the console can be called with >> TX path disabled. Then the system would hang trying to push charecters >> out in atmel_console_putchar(). >> >> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com> >> Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting >> in stop_tx") >> Cc: stable <stable@vger.kernel.org> # 4.4+ >> --- >> Hi Richard, >> >> I found this to fix the problem with system hang in my linux-4.4-at91 branch >> (in the atmel_console_putchar() waiting loop actually). I'm open to more >> insignt. >> As we cannot figure out if this bit is set or not, I didn't preserve the >> current status... >> >> Regards, > > So, I'm guessing that you may see some lines/characters printed twice on > the screen, don't you ? Well, actually, I don't think so because the repetitions that I see are probably due to open/close/open/close/re-open/... of the serial console itself. Same with the line "random: udevd: uninitialized urandom read (16 bytes read, 21 bits of entropy available)", they happen at different moment in time => the printk log timestamping seem to indicate that they are different. Here is my log: http://code.bulix.org/bok23n-123056 Regards, >> drivers/tty/serial/atmel_serial.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c >> index dcebb28ffbc4..7372dbdb7a4c 100644 >> --- a/drivers/tty/serial/atmel_serial.c >> +++ b/drivers/tty/serial/atmel_serial.c >> @@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) >> pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN; >> atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); >> >> + /* Make sure that tx path is actually able to send characters */ >> + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); >> + >> uart_console_write(port, s, count, atmel_console_putchar); >> >> /* >> > > Richard. >
On 15/03/2017 16:29, Nicolas Ferre wrote: > A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA > from transmitting in stop_tx") is that the console can be called with > TX path disabled. Then the system would hang trying to push charecters > out in atmel_console_putchar(). > > Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com> > Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting > in stop_tx") > Cc: stable <stable@vger.kernel.org> # 4.4+ > --- > Hi Richard, > > I found this to fix the problem with system hang in my linux-4.4-at91 branch > (in the atmel_console_putchar() waiting loop actually). I'm open to more > insignt. > As we cannot figure out if this bit is set or not, I didn't preserve the > current status... > > Regards, > > drivers/tty/serial/atmel_serial.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > index dcebb28ffbc4..7372dbdb7a4c 100644 > --- a/drivers/tty/serial/atmel_serial.c > +++ b/drivers/tty/serial/atmel_serial.c > @@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) > pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN; > atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); > > + /* Make sure that tx path is actually able to send characters */ > + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); > + > uart_console_write(port, s, count, atmel_console_putchar); > > /* > Acked-by: Richard Genoud <richard.genoud@gmail.com>
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index dcebb28ffbc4..7372dbdb7a4c 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN; atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); + /* Make sure that tx path is actually able to send characters */ + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); + uart_console_write(port, s, count, atmel_console_putchar); /*
A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting in stop_tx") is that the console can be called with TX path disabled. Then the system would hang trying to push charecters out in atmel_console_putchar(). Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com> Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting in stop_tx") Cc: stable <stable@vger.kernel.org> # 4.4+ --- Hi Richard, I found this to fix the problem with system hang in my linux-4.4-at91 branch (in the atmel_console_putchar() waiting loop actually). I'm open to more insignt. As we cannot figure out if this bit is set or not, I didn't preserve the current status... Regards, drivers/tty/serial/atmel_serial.c | 3 +++ 1 file changed, 3 insertions(+)