Re: [Patch v5 08/13] ARM: imx6q: add config-on-boot gpios

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On Wed, Jun 13, 2012 at 11:50:35AM -0500, Rob Herring wrote:
> On 06/13/2012 10:28 AM, Richard Zhao wrote:
> > On Wed, Jun 13, 2012 at 10:09:54AM -0500, Rob Herring wrote:
> >> On 06/13/2012 07:34 AM, Richard Zhao wrote:
> >>> Sometimes, boards have gpios that don't own by any driver or owner
> >>> by a generic driver that don't like hacks. Such gpios is normally
> >>> output and need setup once on boot. So I introduce the config-on-boot
> >>> gpios.
> >>>
> >>> Signed-off-by: Richard Zhao <richard.zhao@xxxxxxxxxxxxx>
> >>> Cc: Shawn Guo <shawn.guo@xxxxxxxxxx>
> >>> Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
> >>> Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
> >>> ---
> >>>  .../devicetree/bindings/arm/config-on-boot.txt     |   12 +++++++
> >>>  arch/arm/boot/dts/imx6q-sabrelite.dts              |    7 ++++
> >>>  arch/arm/mach-imx/mach-imx6q.c                     |   35 ++++++++++++++++++++
> >>>  3 files changed, 54 insertions(+)
> >>>  create mode 100644 Documentation/devicetree/bindings/arm/config-on-boot.txt
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/arm/config-on-boot.txt b/Documentation/devicetree/bindings/arm/config-on-boot.txt
> >>> new file mode 100644
> >>> index 0000000..f98ed74
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/arm/config-on-boot.txt
> >>> @@ -0,0 +1,12 @@
> >>> +* Configure on Boot
> >>> +
> >>> +Node name: config-on-boot
> >>> +  It must be in root node. config-on-boot means to describe settings that needs
> >>> +  to be set one time on boot but aren't owned by any driver, or the owned driver
> >>> +  is too generic to handle such settings. For example, usb hub uses generic
> >>> +  driver in usb core code, a on-board usb may need deassert reset pin.
> >>
> >> NAK. This is not a h/w description
> > It's misc things, but is hw description.
> 
> You are defining something based on whether linux has a driver or not.
> That should not matter to DT. That's backwards.
I just define the board needs some misc settings. If you think
config-on-boot is not good, we can name it like config-misc.
> 
> >> and should be solved within the
> >> kernel or bootloader. Either fix this in u-boot,
> > Kernel might be better not to depend on uboot.
> >> the platform code, or
> > How do I get gpio in platfrom code without dts description?
> >> make the generic driver support this in a generic way.
> > It's called just after populate devices. It's hard for generic driver to
> > decide when it's called.
> 
> You need to describe that you have a hub on the usb bus and add the gpio
> line to that node. Just like PCI is probe-able, you still need DT nodes
> sometimes for cases like this.
PCI has dev id and may add quirks. But for embedded, I don't know how
to connect a of node to a hub device enumerated by usb core code. And
it may also pollute the usb core code.
> A simpler approach would be to just add
> the gpio to the ehci controller node, but that's not exactly correct.
That's exactly why this patch comes out.

Thanks
Richard
> 
> Rob
> 
> 
> > 
> > Thanks
> > Richard
> >>
> >> Rob
> >>

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