Re: spi-imx: add support for single burst mode (8,16,32)

[Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

On Wed, Jun 01, 2016 at 09:54:39AM +0800, Chris Ruehl wrote:
> On Tuesday, May 31, 2016 07:06 PM, Sascha Hauer wrote:
> >On Tue, May 31, 2016 at 07:43:37AM -0300, Fabio Estevam wrote:
> >>[Adding Sascha and Anton in Cc]
> >>
> >>On Tue, May 31, 2016 at 6:40 AM, Chris Ruehl <chris.ruehl-CR359r9tUDPXPF5Rlphj1Q@public.gmane.org> wrote:
> >>>Hi,
> >>>
> >>>as imx6 using multiple burst to send data to spi slaves and drop the
> >>>chipselect between the words by default my sensor NXP MPL115A1 wasn't
> >>>working.
> >
> >I generally recommend to use GPIO Chip selects. The SPI controller has
> >its own ideas when to assert the chipselects which is hard to match (if
> >possible at all) with what Linux SPI expects. See the cs-gpios device
> >tree property.
> >
> >Sascha
> 
> Sascha that's a good approach to fight this problem, if you have the
> choice. Sadly my hardware design is finished and I can only switch to
> a gpio by run wires on the finished PCB.. and that's not what I want.

I'm not suggesting to change your hardware. Every chipselect pin can be
configured as GPIO aswell, i.e. exchange
MX6QDL_PAD_DISP0_DAT3__ECSPI3_SS0 with MX6QDL_PAD_DISP0_DAT3__GPIO4_IO24
and be done with it.

Sascha

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