On Mon, Apr 11, 2016 at 12:47:23PM -0600, Stephen Warren wrote:
> On 04/11/2016 12:32 PM, Rob Herring wrote:
> > On Mon, Apr 11, 2016 at 11:05 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> > > On 04/11/2016 08:01 AM, Thierry Reding wrote:
> > > >
> > > > From: Thierry Reding <treding@xxxxxxxxxx>
> > > >
> > > > When Tegra124 support was first merged the unit-addresses of all devices
> > > > were listed with a "0," prefix to encode the reg property's second cell.
> > > > It turns out that this notation is not correct, and the "," separator is
> > > > only used to separate fields in the unit address (such as the device and
> > > > function number in PCI devices), not individual cells for addresses with
> > > > more than one cell.
> > >
> > >
> > > > diff --git a/arch/arm/boot/dts/tegra124-jetson-tk1.dts
> > > > b/arch/arm/boot/dts/tegra124-jetson-tk1.dts
> > >
> > >
> > > > - gpu@0,57000000 {
> > > > + gpu@57000000 {
> > > > /*
> > > > * Node left disabled on purpose - the bootloader will
> > > > enable
> > > > * it after having set the VPR up
> > >
> > >
> > > So the bootloader doesn't actually do that for the new node name at present.
> > > I have written a patch to make it do so, but haven't sent it yet since I
> > > wrote it in the middle of a large cleanup of U-Boot. I expect I can shuffle
> > > it to the front of the series and send it soon though. Without a new
> > > bootloader that contains this change, IIUC all graphics will be
> > > non-operative if this change is applied.
> >
> > Then you should leave this one alone for a while.
> >
> > I also found this looking at u-boot:
> >
> > arch/arm/dts/tegra124.dtsi: gpu@57000000 {
>
> FWIW, that's because the U-Boot DTs use #address-cells=<1> on this chip so
> there was no question of using commas in the unit address or not. That may
> have been because U-Boot imported the DTs (or parts of them) from Linux
> before Linux switched to #address-cells=<2> on this chip.
I thought the reason had been that U-Boot didn't support any more than
32-bits for addresses on 32-bit ARM anyway, hence we never bothered to
sync with the kernel DTS files regarding #address-cells.
Technically it would be possible for someone to write a DTS file with a
GPU node with yet another name (the binding after all doesn't specify
what the node name should be) so I think better matching would be safer
in any case.
Thierry
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