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

[Phil Edworthy]

Hi Jagan,

On 06 December 2016 17:24 Jagan Teki wrote:
> On Tue, Dec 6, 2016 at 6:00 PM, Phil Edworthy <phil.edworthy at renesas.com>
> wrote:
> > 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?
> 
> I can drop 10 and 11 from the series, is that OK?
Yes please!

Thanks
Phil