[PATCH] i2c: mxs: remove broken PIOQUEUE support

On Thu, Nov 01, 2012 at 03:28:17PM +0100, Marek Vasut wrote:

Dear Wolfram Sang,

quoted

This I2C master can do DMA and PIOQUEUE (PIO with FIFO). Originally,
only PIOQEUE

PIOQUEUE ;-)

Yup, right!

quoted

was supported, then DMA support was added. The original
intention was to keep PIOQUEUE since it has less overhead what is nice
for small transfers. However, runtime switching between PIOQEUE and DMA
depending on the transfer size never worked despite a lot of trying.
Since PIOQUEUE mode itself was flaky (polling at places where interrupts
failed to work) and the implementation also imposed a size limit for
transfers, it is best to remove the support altogether which makes the
driver a lot cleaner and more robust. If somebody really wants less
overhead, plain PIO mode could still be implemented with the addidtional
advantage that this mode is also available on MX23, too.

Yes, looks to be the way to go.

Reviewed-by: Marek Vasut <marex@denx.de>

Thanks.

BTW have you tried combining all i2c-messages (msgs[]) of the transfer
into one DMA chain? That would reduce overhead, too, no?

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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