[PATCH v2 1/4] spi: imx: GPIO based chip selects should not be required

[Mark Brown]

On Tue, Oct 31, 2017 at 04:57:42PM +0000, Trent Piepho wrote:
> On Tue, 2017-10-31 at 11:19 +0000, Mark Brown wrote:

> > Do the native chip selects actually work usefully on this hardware?
> > There used to be problems with it wanting to do things like bounce the
> > chip select on every word which made it extremely difficult to use with
> > Linux.

> Still are annoying, but on the device we have connected to it, it ends
> up working as desired.

> I've not thoroughly investigated this hardware to find the details. 
> IIRC, the designware SPI on Altera SoCFPGA had the same issue, but it
> was a flaw in the driver and I was able to fix it.  I've come to expect
> it, as every new SPI master I use doesn't work properly in some
> different way.

It's one of the reasons why I'm suspicous of making the GPIO optional,
lots of chips use GPIO chipselects because a lot of the breakage is
confined to chip select handling and I remember the i.MX as being
especially far from useful.
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