Re: [PATCH v3 3/5] spi: dw: Add support for master mode selection for DWC SSI controller

[Mark Brown]

On Thu, Nov 11, 2021 at 05:52:46PM +0300, Serge Semin wrote:
> On Thu, Nov 11, 2021 at 02:16:05PM +0000, Mark Brown wrote:
> > On Thu, Nov 11, 2021 at 02:51:59PM +0800, nandhini.srikandan@xxxxxxxxx wrote:

> > > Add support to select the controller mode as master mode by setting
> > > Bit 31 of CTRLR0 register. This feature is supported for controller
> > > versions above v1.02.

> > Clearly older versions of the controller can also run in this mode...

> Yes, but the driver doesn't support the slave mode at the moment.
> So always enabling the master mode seems natural. (see my next comment
> also concerning this matter)

The commit message makes it sound like master mode is only supported for
the newer versions.

> > This makes the configuration unconditional, it's not gated by controller
> > version checks or any kind of quirk any more meaning that if anything

> We have already discussed this feature in v2:
> https://patchwork.kernel.org/project/spi-devel-general/patch/20210824085856.12714-3-nandhini.srikandan@xxxxxxxxx/
> Since that bit has been reserved before 1.02a but is no available for
> any DWC SSI controller and the driver doesn't support the SPI-slave mode
> at the moment I suggested to just always set that flag for the DWC SSI
> code. Please see my reply to Nandhini here:

Given that people seem to frequently customise these IPs when
integrating them I wouldn't trust people not to have added some other
control into that reserved bit doing some magic stuff that's useful in
their system.

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