RE: [PATCH] spi: lpspi: Add cs-gpio support

[Clark Wang]

> -----Original Message-----
> From: Mark Brown <broonie@xxxxxxxxxx>
> Sent: Tuesday, December 11, 2018 22:26
> To: Clark Wang <xiaoning.wang@xxxxxxx>
> Cc: linux-spi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] spi: lpspi: Add cs-gpio support
> 
> On Tue, Dec 04, 2018 at 06:24:59AM +0000, Clark Wang wrote:
> 
> > Add cs-gpio feature for LPSPI. Use fsl_lpspi_prepare_message() and
> > fsl_lpspi_unprepare_message() to enable and control cs line.
> > These two functions will be only called at the beginning and the
> > ending of a message transfer.
> 
> > Still support using the mode without cs-gpio. It depends on if
> > attribute cs-gpio has been configured in dts file.
> 
> Why is this not using the core support for GPIO chip selects?  Note that you
> can't just implement chip select in the prepare and unprepare, drivers can
> toggle chip select within a message so the code should be looking at the
> individual transfers to see if cs_change is set and acting accordingly.

Ok, I will try to use the core support for GPIO chip selects.

Regards,
Clark Wang