spi-imx: real time operation

spi-imx: real time operation

[Jakub Kicinski]

Hi Markus!

I've seen your patch from July which added rt parameter to spi-imx [1].
If I understand the code correctly spi-imx is using bitbang, therefore
it uses old SPI API, therefore the message pump does not apply to it,
therefore setting master->rt has no effect.

Is my understanding correct?  If so before I convert spi-imx not to use
bitbang I would like to ask you if you have not already done it? ;)

Without SPI threads running with RT prio I can't even reliably use an
sc16is7xx UART at 115200...

[1] http://www.spinics.net/lists/arm-kernel/msg348713.html


Thanks
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Re: spi-imx: real time operation

[Jakub Kiciński]

On Wed, 15 Apr 2015 17:09:36 +0200, Jakub Kicinski wrote:
> Hi Markus!
> 
> I've seen your patch from July which added rt parameter to spi-imx [1].
> If I understand the code correctly spi-imx is using bitbang, therefore
> it uses old SPI API, therefore the message pump does not apply to it,
> therefore setting master->rt has no effect.
> 
> Is my understanding correct?  If so before I convert spi-imx not to use
> bitbang I would like to ask you if you have not already done it? ;)
> 
> Without SPI threads running with RT prio I can't even reliably use an
> sc16is7xx UART at 115200...
> 
> [1] http://www.spinics.net/lists/arm-kernel/msg348713.html

Ugh.. I missed 2025172e3280 ("spi/bitbang: Use core message pump"),
working with old kernels bit my in the rear end.

Sorry for the noise.
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