Re: [PATCH] serial: 8250_dw: Fix runtime PM handling
From: Guenter Roeck
Date: Fri Sep 28 2018 - 18:41:03 EST
On Thu, May 10, 2018 at 03:13:56PM +0100, Phil Edworthy wrote:
> When using kgdb, you get an abort when accessing the UART registers.
> This is because the driver has already entered runtime PM and so turned
> off the bus clock needed to access the registers.
>
> To fix this, set the capability indicating Runtime PM is active while idle.
>
With this patch applied, I get the already reported traceback [1].
Obviously neither the promised revert [2] nor the presumed fix [3] made it
into the mainline Kernel.
Greg, can you please revert this patch ? If people don't care enough
to fix the problem, we should at least not have to suffer the consequences.
Thanks,
Guenter
> Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_dw.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 0529b5cc094b..aff04f1de3a5 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -576,6 +576,10 @@ static int dw8250_probe(struct platform_device *pdev)
> if (!data->skip_autocfg)
> dw8250_setup_port(p);
>
> +#ifdef CONFIG_PM
> + uart.capabilities |= UART_CAP_RPM;
> +#endif
> +
> /* If we have a valid fifosize, try hooking up DMA */
> if (p->fifosize) {
> data->dma.rxconf.src_maxburst = p->fifosize / 4;
> --
> 2.7.4
---
[1] https://www.spinics.net/lists/linux-serial/msg30379.html
[2] https://www.spinics.net/lists/linux-serial/msg30380.html
[3] https://www.spinics.net/lists/linux-serial/msg30757.html