On Thu, Nov 17, 2016 at 04:35:10PM +0100, Stefan Wahren wrote:
> Hi John,
>
> Am 17.11.2016 um 00:47 schrieb John Youn:
> > Add the "snps,ahb-burst" binding and read it in.
> >
> > This property controls which burst type to perform on the AHB bus as a
> > master in internal DMA mode. This overrides the legacy param value,
> > which we need to keep around for now since several platforms use it.
> >
> > Some platforms may see better or worse performance based on this
> > value. The HAPS platform is one example where all INCRx have worse
> > performance than INCR.
> >
> > Other platforms (such as the Canyonlands board) report that the default
> > value causes system hangs.
> >
> > Signed-off-by: John Youn <johnyoun@xxxxxxxxxxxx>
> > Cc: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx>
> > ---
> > Documentation/devicetree/bindings/usb/dwc2.txt | 2 +
> > drivers/usb/dwc2/core.h | 9 +++++
> > drivers/usb/dwc2/params.c | 56 ++++++++++++++++++++++++++
> > 3 files changed, 67 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/usb/dwc2.txt b/Documentation/devicetree/bindings/usb/dwc2.txt
> > index 6c7c2bce..9e7b4b4 100644
> > --- a/Documentation/devicetree/bindings/usb/dwc2.txt
> > +++ b/Documentation/devicetree/bindings/usb/dwc2.txt
>
> according to Documentation/devicetree/bindings/submitting-patches.txt
> this change should be a separate patch.
>
> > @@ -26,6 +26,8 @@ Optional properties:
> > Refer to phy/phy-bindings.txt for generic phy consumer properties
> > - dr_mode: shall be one of "host", "peripheral" and "otg"
> > Refer to usb/generic.txt
> > +- snps,ahb-burst: specifies the ahb burst length. Valid arguments are:
> > + "SINGLE", "INCR", "INCR4", "INCR8", "INCR16". Defaults to "INCR4".
>
> This doesn't apply in case of the bcm2835. I would prefer this option is
> ignored in that case with a dev_warn("snps,ahb-burst is not supported on
> this platform").
Also, perhaps you should allow that the compatible string can define the
default.
Rob
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