Re: [Xen-devel] [PATCH] PL011: fix reverse logic for interrupt mask register

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 08/13/2013 04:12 PM, Andre Przywara wrote:
> The PL011 IMSC register description is somehow fuzzy in the
> documentation; by comparing it with the Linux implementation one can
> see that the logic is actually reversed to Xen's implementation:
> A "0" in field means interrupt disabled, a "1" enables it.
> Therefore we enabled all interrupts instead of disabling them in the
> beginning and later on masked the wrong interrupts.
> Unclear how this worked on the Versatile Express, but this fix is
> needed to get Calxeda Midway running (and works on VExpress, too).

On my Versatile Express, the keyboard is unusable with this patch.
Xen receives random keys and sometimes nothing is printed on the serial
port.

By reverting this patch on my tree, I'm able to use correctly the serial
port.

> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> ---
>  xen/drivers/char/pl011.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/drivers/char/pl011.c b/xen/drivers/char/pl011.c
> index 05d034f..8e90520 100644
> --- a/xen/drivers/char/pl011.c
> +++ b/xen/drivers/char/pl011.c
> @@ -87,7 +87,7 @@ static void __init pl011_init_preirq(struct serial_port 
> *port)
>      unsigned int divisor;
>  
>      /* No interrupts, please. */
> -    pl011_write(uart, IMSC, ALLI);
> +    pl011_write(uart, IMSC, 0);
>  
>      /* Definitely no DMA */
>      pl011_write(uart, DMACR, 0x0);
> @@ -115,7 +115,7 @@ static void __init pl011_init_preirq(struct serial_port 
> *port)
>      pl011_write(uart, RSR, 0);
>  
>      /* Mask and clear the interrupts */
> -    pl011_write(uart, IMSC, ALLI);
> +    pl011_write(uart, IMSC, 0);
>      pl011_write(uart, ICR, ALLI);
>  
>      /* Enable the UART for RX and TX; no flow ctrl */
> @@ -140,7 +140,7 @@ static void __init pl011_init_postirq(struct serial_port 
> *port)
>      pl011_write(uart, ICR, OEI|BEI|PEI|FEI);
>  
>      /* Unmask interrupts */
> -    pl011_write(uart, IMSC, RTI|DSRMI|DCDMI|CTSMI|RIMI);
> +    pl011_write(uart, IMSC, OEI|BEI|PEI|FEI|TXI|RXI);
>  }
>  
>  static void pl011_suspend(struct serial_port *port)
> 


-- 
Julien Grall

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