Re: Fwd: PXA270 + ads7846 (TI TSC2046)

[David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>]

On Friday 04 May 2007, Anton Vorontsov wrote:

> Why Motorola hardcoded in pxa2xx spi driver? Is that means that with
> Motorola bit set we can do all we can with National bit? If not (and
> from my observation it's not) is that means that we can't use pxa2xx
> spi driver for chips requiring National/Microwire?

Modulo the misconception there -- Microwire being a strict subset
of the pure SPI/Motorola mode -- one other issue came up recently.

It seems that the patch making drivers/input/touchscreen/ads7846.c
use SPI_MODE_1 was incorrect.  It should use SPI_MODE_0 ... since
it uses normal clock polarity (CPOL=0) and samples on the leading
edge of that clock (CPHA=0).

When I tested -- with omap_uwire and pxa2xx_spi -- I used SPI_MODE_0;
but it was later changed.  It seems that when it's used with the
omap_uwire driver, SPI_MODE_1 also works.  That might explain some
of the problems observed...

- Dave



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