[U-Boot] [PATCH v3 11/11] spi: cadence_qspi: Support specifying the sample edge used

[Phil Edworthy]

Hi Jagan, Marek,

On 06 December 2016 12:39 Marek Vasut wrote:
> On 12/06/2016 11:25 AM, Phil Edworthy wrote:
> > On 05 December 2016 13:31, Marek Vasut wrote:
> >> On 12/05/2016 11:46 AM, Phil Edworthy wrote:
> >>> On 05 December 2016 10:42, Jagan Teki wrote:
> >>>> On Mon, Dec 5, 2016 at 11:31 AM, Phil Edworthy
> >>>> <phil.edworthy at renesas.com> wrote:
> >>>>> On 05 December 2016 10:26, Jagan Teki wrote:
> >>>>>> On Mon, Dec 5, 2016 at 11:09 AM, Phil Edworthy
> >>>>>> <phil.edworthy at renesas.com> wrote:
> >>>>>>> On 02 December 2016 14:23, Jagan Teki wrote:
> >>>>>>>> On Tue, Nov 29, 2016 at 6:28 PM, Phil Edworthy
> >>>>>>>> <phil.edworthy at renesas.com> wrote:
> >>>>>>>>> Introduce a new DT property to specify whether the QSPI Controller
> >>>>>>>>> samples the data on a rising edge. The default is falling edge.
> >>>>>>>>> Some versions of the QSPI Controller do not implement this bit, in
> >>>>>>>>> which case the property should be omitted.
<snip>

> >>>>>>>> Code look reasonable, but how Linux handling this with the same dt
> >>>>>>>> property, any idea? I couldn't find it either.
> >>>>>>> The Linux driver does not yet have this property. Is there a policy to add
> >> new
> >>>>>>> props to Linux first?
> >>>>>>
> >>>>>> If the same/equal code used in Linux better to have the same property
> >>>>>> instead of another name used in U-boot?
> >>>>> Of course, but I cannot see this in Linux:
> >>>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-
> >>>> next.git/tree/Documentation/devicetree/bindings/spi/spi-cadence.txt
> >>>>
> >>>> Yeah, I saw this. Do you have any idea how Linux handling this sample
> edge?
> >>> The same way U-Boot currently handles it, i.e. it does nothing with this.
> >> Intel/Altera
> >>> (Chin Liang) said that they do not have this bit in their version of the Cadence
> >> QSPI
> >>> Controller.
> >>>
> >>> We are using a later version that has had this bit added.
> >>
> >> You were looking at the wrong bindings:
> >> https://git.kernel.org/cgit/linux/kernel/git/next/linux-
> >> next.git/tree/Documentation/devicetree/bindings/mtd/cadence-quadspi.txt
> > Thanks for pointing that out!
> >
> >> but yes, Linux does not do support the data edge toggling. I think there
> >> was another QSPI patch in Linux which tried adding such property, so
> >> check linux-mtd for it. Generic one would be great.
> > I had a search around, but couldn't find anything.
> 
> Look for negative_edge here:
> http://www.spinics.net/lists/devicetree/msg153582.html
> 
> >> And no, there is no policy for pushing new props to linux first. New DT
> >> props should ideally get approved via devicetree at vger though, but that's
> >> about it. Also, while I tried backporting the Linux CQSPI driver to
> >> U-Boot, but unfortunately, it turned out to be extremely difficult due
> >> significant differences between the Linux and U-Boot SPI NOR  framework.
> > OK, thanks for the information.

Since it will take a bit more time to get a generic prop for the sample edge to
be ack'd by devicetree at vger, would it make sense to drop it from this series,
so we can get the rest in?

Thanks
Phil