Re: [PATCHv2 1/3] dt-bindings: spi: cadence-quadspi: document "cdns,qspi-nor-ver-00-10"

[Pratyush Yadav <p.yadav@ti.com>]

On 15/12/21 09:36AM, Dinh Nguyen wrote:
> 
> 
> On 12/14/21 2:05 PM, Pratyush Yadav wrote:
> > On 08/12/21 05:45PM, Dinh Nguyen wrote:
> > > On Mon, Dec 6, 2021 at 9:51 PM Pratyush Yadav <p.yadav@ti.com> wrote:
> > > > 
> > > > On 03/12/21 12:17PM, Dinh Nguyen wrote:
> > > > > The QSPI controller on Intel's SoCFPGA platform does not implement the
> > > > > CQSPI_REG_WR_COMPLETION_CTRL register, thus a write to this register
> > > > > results in a crash.
> > > > > 
> > > > > The module/revision ID is written in the MODULE_ID register. For this
> > > > > variance, bits 23-8 is 0x0010.
> > > > 
> > > > When I looked at your original patches I was under the impression that
> > > > this was a SoCFPGA specific thing and did not apply to other
> > > > implementation of the IP in general.
> > > > 
> > > > If this is indeed a generic thing and we can detect it via the MODULE_ID
> > > > register [0], then why not just read that register at probe time and
> > > > apply this quirk based on the ID? Why then do we need a separate
> > > > compatible at all?
> > > > 
> > > > [0] I would like to see it stated explicitly somewhere that version
> > > > 0x0010 does not support the WR_COMPLETION_CTRL register.
> > > > 
> > > 
> > > I cannot for sure confirm that this condition applies to only 0x0010
> > > version of the
> > > IP. I can verify that the IP that is in all 3 generations of SoCFPGA
> > > devices, all have
> > > MODULE_ID value of 0x0010 and all do not have the WR_COMPLETION_CTRL
> > > register implemented.
> > 
> > I agree with Rob here. If you are not sure that this is a generic IP
> > thing then you should not use a generic compatible.
> > 
> 
> 
> I think using the binding of "intel,socfpga-qspi" should be fine? If we go
> by the MODULE_ID value as a indicator of versions, then the version hasn't
> changed for all revisions of the SoCFPGA, dating back to the original
> Cyclone5, which was introduced in 2012.

Yes, I think you should keep using the SoC specific binding unless you 
can find some documentation from Cadence that says all parts with this 
MODULE_ID value don't have the WR_COMPLETION_CTRL register.

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.