Re: [PATCH v4 0/8] serial: qcom-geni: Overhaul TX handling to fix crashes/hangs

[neil.armstrong@linaro.org]

On 11/06/2024 00:24, Douglas Anderson wrote:
> 
> While trying to reproduce -EBUSY errors that our lab was getting in
> suspend/resume testing, I ended up finding a whole pile of problems
> with the Qualcomm GENI serial driver. I've posted a fix for the -EBUSY
> issue separately [1]. This series is fixing all of the Qualcomm GENI
> problems that I found.
> 
> As far as I can tell most of the problems have been in the Qualcomm
> GENI serial driver since inception, but it can be noted that the
> behavior got worse with the new kfifo changes. Previously when the OS
> took data out of the circular queue we'd just spit stale data onto the
> serial port. Now we'll hard lockup. :-P
> 
> I've tried to break this series up as much as possible to make it
> easier to understand but the final patch is still a lot of change at
> once. Hopefully it's OK.
> 
> [1] https://lore.kernel.org/r/20240530084841.v2.1.I2395e66cf70c6e67d774c56943825c289b9c13e4@changeid
> 
> Changes in v4:
> - Add GP_LENGTH field definition.
> - Fix indentation.
> - GENMASK(31, 0) -> GP_LENGTH.
> - Use uart_fifo_timeout_ms() for timeout.
> - tty: serial: Add uart_fifo_timeout_ms()
> 
> Changes in v3:
> - 0xffffffff => GENMASK(31, 0)
> - Reword commit message.
> - Use uart_fifo_timeout() for timeout.
> 
> Changes in v2:
> - Totally rework / rename patch to handle suspend while active xfer
> - serial: qcom-geni: Fix arg types for qcom_geni_serial_poll_bit()
> - serial: qcom-geni: Fix the timeout in qcom_geni_serial_poll_bit()
> - serial: qcom-geni: Introduce qcom_geni_serial_poll_bitfield()
> - serial: qcom-geni: Just set the watermark level once
> - serial: qcom-geni: Rework TX in FIFO mode to fix hangs/lockups
> - soc: qcom: geni-se: Add GP_LENGTH/IRQ_EN_SET/IRQ_EN_CLEAR registers
> 
> Douglas Anderson (8):
>    soc: qcom: geni-se: Add GP_LENGTH/IRQ_EN_SET/IRQ_EN_CLEAR registers
>    tty: serial: Add uart_fifo_timeout_ms()
>    serial: qcom-geni: Fix the timeout in qcom_geni_serial_poll_bit()
>    serial: qcom-geni: Fix arg types for qcom_geni_serial_poll_bit()
>    serial: qcom-geni: Introduce qcom_geni_serial_poll_bitfield()
>    serial: qcom-geni: Just set the watermark level once
>    serial: qcom-geni: Fix suspend while active UART xfer
>    serial: qcom-geni: Rework TX in FIFO mode to fix hangs/lockups
> 
>   drivers/tty/serial/qcom_geni_serial.c | 322 +++++++++++++++-----------
>   include/linux/serial_core.h           |  15 +-
>   include/linux/soc/qcom/geni-se.h      |   9 +
>   3 files changed, 206 insertions(+), 140 deletions(-)
> 

Indeed no more lockup when killing a process on the serial debug console

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK

Thanks !
Neil