RE: [PATCH][RFC] spi: sh-msiof: Configure MSIOF sync signal timing in device tree

[yoshihiro shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>]

Hi Geert-san, Laurent-san,

Thank you very much for your comments!

> On Sun, Nov 30, 2014 at 9:23 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> > On Friday 28 November 2014 12:45:27 Yoshihiro Shimoda wrote:
> >> The MSIOF controller has DTDL and SYNCDL in SITMDR1 and SIRMDR1
> >> registers. So, this patch adds new properties like the following
> >> commit:
> >>   d0fb47a5237d8b9576113568bacfd27892308b62
> >>   (spi: fsl-espi: Configure FSL eSPI CSBEF and CSAFT)
> >>
> >> The DTDL is the chip select (SYNC) setup time.
> >>  b'000: No bit delay
> >>  b'001: 1-clock-cycle delay
> >>  b'010: 2-clock-cycle delay
> >>  b'101: 0.5-clock-cycle delay
> >>  b'110: 1.5-clock-cycle delay
> >>
> >> The SYNCDL is the chip select (SYNC) hold time.
> >>  b'000: No bit delay
> >>  b'001: 1-clock-cycle delay
> >>  b'010: 2-clock-cycle delay
> >>  b'011: 3-clock-cycle delay
> >>  b'101: 0.5-clock-cycle delay
> >>  b'110: 1.5-clock-cycle delay
> 
> You forgot to quote the last line from the DTDL and SYNCDL paragraphs:
> 
> | In case of SPI mode, only 000 is allowed to set to this field.

Thank you for the point!
I asked HW team about the paragraphs. And then, the paragraphs are correct.

> And the spi-sh-msiof driver is using the MSIOF in SPI mode???

Yes, the driver is using the MSIOF in SPI mode.
So, we have no chance to set the DTDL and SYNCDL to 0 in SPI mode.

I should have looked into the datasheet more before I sent this RFC.

< snip >
> > Was it really the intent of this patch to add DT properties without
> > providing an implementation in the sh-msiof driver ?
> 
> Given the sentence "If this patch is reasonable, I will modify the sh-msiof driver." in the introduction, I think so.

Yes, I meant that.

Best regards,
Yoshihiro Shimoda

> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> 
> In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say
> "programmer" or something like that.
>                                 -- Linus Torvalds
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