Re: [PATCH] spi: pl022: Remove timeout in polling mode operation

[Lars-Peter Clausen <lars@xxxxxxxxxx>]

On 07/15/2018 12:01 PM, Linus Walleij wrote:
> On Fri, Jul 13, 2018 at 5:27 PM Alexander Sverdlin
> <alexander.sverdlin@xxxxxxxxx> wrote:
> 
>> Some tests show, that bulk SPI accesses (255 bytes, maximum PL022 can) may
>> take seconds, depending on CPU load. In this case vital SPI accesses can
>> fail because of user-space applications. Some other drivers already do not
>> have timeouts in polling mode.
>>
>> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
> 
> Wow what system is this and how does that happen?
> 
> I guess it is fine, but the timeout is there for a reason still. What about
> setting the timeout to a minute or something?

How about resetting the timeout if there is progress? E.g. have
readwriter() return whether it was able to read or write some data and
then reset the timeout. If the timeout is due to CPU contention
readwriter() should always be able to push/pull new data to/from the
hardware.
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