Tegra board file deprecation schedule

[Marc Dietrich]

Hi,

On Friday 27 April 2012 14:39:35 Olof Johansson wrote:
> On Fri, Apr 27, 2012 at 2:24 PM, Stephen Warren <swarren at wwwdotorg.org> 
wrote:
> > Eventually, Tegra support will become device tree only in the mainline
> > kernel; arch/arm/mach-tegra/board* will be deleted.
> > 
> > I propose the following policy towards this goal: I'd like to maintain
> > the board files until the relevant device tree file has the same level
> > of functionality. Once that is achieved, and a Linus kernel is release
> > with full support for the board via device tree, the board files can be
> > deleted from the next kernel release.
> > 
> > Does anyone have any issues with this?
> 
> Sounds great, but I think you can be more aggressive than this; no
> need to keep the non-DT board alive for the final release.
> 
> > The device tree conversion status is:
> > 
> > Cardhu/Ventana:
> > 
> > None; already device tree only
> > 
> > Seaboard:
> > 
> > Kaen and Wario board variants are not explicitly supported via device
> > tree. However, the differences are almost entirely minor (at least as
> > far as the current features supported in board-seaboard*), so anyone
> > wishing to use those board variants could easily create their own device
> > tree files. I plan to ignore Kaen/Wario and delete board-seaboard* in
> > 3.6 unless someone objects.
> 
> Wario is no longer an active platform and can be completely removed;
> I'll post patches for this.
> 
> Kaen is somewhat active, but I can send a device tree for it;
> definitely ok to sunset before it's in since we can carry it locally
> in our downstream kernel tree if needed.
> 
> > Harmony:
> > 
> > Missing support for TPS6586x regulator, and PCI-Express controller.
> > Thierry is working on this. I hope this support will be ready to be
> > merged for 3.6, and hence board-harmony* can be deleted in 3.7.
> > 
> > TrimSlice:
> > 
> > Missing RTC and Micro-SD slot support. I've sent patches for this, which
> > will be merged today.
> > 
> > Missing audio support. I sent patches for this today. I hope they'll be
> > merged for 3.5.
> > 
> > Missing PCI-Express support; status above.
> > 
> > I hope board-trimslice* can be deleted in 3.7.
> > 
> > Paz00/Toshiba AC100:
> > 
> > Missing rfkill button support. Defining a good binding for this might
> > prove challenging. Marc Dietrich started work on this a while back. I
> > pinged him to see if he intends to continue this work.

I got no response after my last suggestion to add it below the corresponding 
usb controller [1]. It wasn't a clever idea anyway I think. So the best 
solution would be as Olof suggested to add it as a platform_device. See my 
original patch [2]. If this is ok, I can send a rebased version, and hope that 
the DT people accept it.

Some other things regarding board removal also came into my mind. First, is 
the sdhci order problem solved? Maybe I missed it, but it would be nice if we 
could give the internal emmc a device number of zero and the external reader a 
device number one. Currently it is oposite around and AFAIK device tree 
guaranties no special order unless you enforce it somehow.

Another (maybe a bit off-topic) thing that puzzels me is the how to assign the 
clock to the nvec. The device needs the clock (tegra-i2c.2) but there is no 
sane way to get it. I was thinking to add an device name alias (nvec = tegra-
i2c.2) to the board file so I can use clk_get(&pdev->dev, NULL) instead of 
clk_get_sys which seems to be unwanted. Is it possible to add a "clock" 
property to it?

Otherwise I'm fine with board file removal.

Marc

[1] http://permalink.gmane.org/gmane.linux.ports.tegra/3456
[2] http://permalink.gmane.org/gmane.linux.ports.tegra/3415


> > 
> > This is probably the long-pole for completely removing board files,
> > unless we ignore the rfkill feature and delete the board files anyway.
> 
> if this is the only thing holding it up sunsetting all non-DT boards
> on tegra then I suggest just adding a one-time runtime test that adds
> a platform device on that device tree platform. As long as there
> aren't more of them creeping in over time that should be OK.