Re: [PATCH] spi: dt-bindings: clarify CS behavior for spi-cs-high and gpio descriptors

[Andreas Kemnade <andreas@xxxxxxxxxxxx>]

On Wed, 9 Dec 2020 14:04:26 -0500
Sven Van Asbroeck <thesven73@xxxxxxxxx> wrote:

> On Wed, Dec 9, 2020 at 1:16 PM H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> wrote:
> >
> > This is also what made me wonder if that is really intended because then
> > the whole discussion about the cs-gpio-flags and inversion and the fixes
> > would not have been needed. The current code and fixes are all about
> > not ignoring the flags...  
> 
> The inversion you witnessed was a bug caused by spi client drivers that
> simply "plow over" the SPI_CS_HIGH mode flag. This includes the panel driver
> you're using, see:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c?h=v5.10-rc6#n337
> 
ah, it would be set in spi->mode and is cleared by

spi->mode = SPI_MODE_3;


Hmm, but we have
                      spi-cpol;
                        spi-cpha;
in devicetree. Why do we need that spi->mode line at all?

Regards,
Andreas