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

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Sorry, I've gotten behind while traveling. I cleared a bunch of backlog this 
afternoon but didn't manage to get to this one. I hope I can review it tomorrow.

Ian. (Sorry for top post, on my phone)

Andre Przywara <andre.przywara@xxxxxxxxxx> wrote:

>On 08/13/2013 05:12 PM, Andre Przywara wrote:
>
>Ian,
>
>what about this one?
>This is a real showstopper on Midway.
>
>Thanks,
>Andre.
>
>> 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).
>>
>> 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)
>>
>
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