[PATCH v1] x86: acpi: Refactor XSDT handling in acpi_add_table()

[Simon Glass]

Hi Andy,

On Tue, 3 Mar 2020 at 02:23, Andy Shevchenko <andy.shevchenko at gmail.com> wrote:
>
> On Tue, Mar 3, 2020 at 1:36 AM Simon Glass <sjg at chromium.org> wrote:
> > On Mon, 2 Mar 2020 at 13:47, Andy Shevchenko <andy.shevchenko at gmail.com> wrote:
> > > On Mon, Mar 2, 2020 at 9:47 PM Simon Glass <sjg at chromium.org> wrote:
> > > > On Fri, 28 Feb 2020 at 01:47, Andy Shevchenko <andy.shevchenko at gmail.com> wrote:
> > > > > On Fri, Feb 28, 2020 at 1:41 AM Simon Glass <sjg at chromium.org> wrote:
> > > > > > On Thu, 27 Feb 2020 at 06:00, Andy Shevchenko
> > > > > > <andriy.shevchenko at linux.intel.com> wrote:
> > > > >
> > > > > > Could you take a look at the ACPI series?
> > > > > >
> > > > > > It was sent out about a month ago and has a refactor to this function.
> > > > > >
> > > > > > u-boot-dm/coral-working
> > > > >
> > > > > There are tons of changes. Care to point what changes are more
> > > > > important (generic to all x86)?
> > > >
> > > > I'm not quite sure about that...but x86 patches have an x86: tag, so
> > > > perhaps that helps?
> > >
> > > Okay, some like 50 of them or even more? I really don't want to spend
> > > time on the board related patches like "x86: apl:".
> >
> > Well that's why I add the tags, so you can see what they relate to.
> > This is probably a good one to review:
> >
> >  dm: core: Add basic ACPI support
>
> Okay, I will try to find a time to look at it first.
>
> > > > > P.S. Briefly looking at the last ~30 patches I can say that the idea
> > > > > looks good, implementation needs more work. For example, there is
> > > > > 'linux,name' property. Shouldn't be referred at all. Linux names and
> > > > > other type of enumerations is utterly opaque to the outside world.
> > > >
> > > > How do we add the required linux,name ACPI property into the ACPI
> > > > tables for a device?
> > >
> > > There must not be Linux device names or anything Linux related (like
> > > hardcoded GPIO numbers) in the ACPI table.
> >
> > Apparently the Intel GPIO driver requires that name. See for example here:
> >
> > https://elixir.bootlin.com/linux/latest/source/drivers/pinctrl/intel/pinctrl-broxton.c#L999
> >
> > static const struct acpi_device_id bxt_pinctrl_acpi_match[] = {
> > { "INT3452", (kernel_ulong_t)apl_pinctrl_soc_data },
> > { "INT34D1", (kernel_ulong_t)bxt_pinctrl_soc_data },
> > { }
> > };
> >
> > So we have to put INT3452 in the ACPI table.
>
> Wait, this is not a *name*, this is ACPI _HID. ACPI _HID, of course,
> should be somewhere in board code.
>
> I was thinking myself about some U-Boot framework that actually takes
> ACPI _HID from the driver. So, when you define in U-Boot device tree a
> compatible string (for U-Boot use), in the driver it will have in the
> class structure the callback / field / stubstructure to use when ACPI
> generate tables is enabled. It will drop duplication of compatible
> with ACPI _HID in each DTS.

Why are you so opposed to using device tree for this? The GPIO and
pinctrl drivers are intended to be generic....what a pain to add all
this stuff into the tables in the driver!

When other platforms use APL we can move some .dts nodes over into a
intel-apl.dtsi file (or similar) to deal with any duplication. Of
course we don't want duplication.

Re the thread that Wolfgang references, I'm going to have a close look
at that and hopefully simplify things. We still need quite a bit more
patches to be reviewed before it is worth sending again, I think.

>
> But to the current topic, you put *instance* (not even _HID) to the DT
> with property called "linux,name". It's inappropriate. NAK for that
> for sure.

OK, so are you saying the property name (linux-name) should change? We
have acpi,name elsewhere but I don't think that is the _HID.

Or are you saying that the "INT3452:" should be factored out and it
should know the 00/01/0203 by its position in the device tree?

>
> > > > > On top of that, I think we rather need to have a conversion layer than
> > > > > putting some names inside DT, like \_SB_.GPO0 should be generated
> > > > > automatically from DT node. That said, I don't like DT being polluted
> > > > > with non-DT stuff.
> > > >
> > > > Well DT is the configuration mechanism for U-Boot.
> > > >
> > > > \_SB_.GPO0 is a special case since it actually refers to pinctrl (ACPI
> > > > seems to make no distinction between pinctrl and GPIO) and this node
> > > > is inside p2sb:
> > > >
> > > > pci {
> > > >    p2sb at d,0 {
> > > >       n {
> > > >          gpio-n {
> > > >
> > > > So the automatically generated path would have p2sb in it. The same
> > > > work-around is in coreboot.
> > >
> > > It's not a coreboot, we may do better, right?
> > > So, generation can strip p2sb (special case) from all p2sb devices.
> > > However, I'm not sure I understand how p2sb is involved in GPIO
> > > enumeration,
> >
> > Well the only other way to create a path is to work up to the root and
> > build it node by node. I wonder if we could make p2sb be transparent?
> > I tried that but hit a problem.
> >
> > Coreboot has these really awful (IMO) functions that are repeated for every SoC:
> >
> > https://github.com/coreboot/coreboot/blob/master/src/soc/amd/stoneyridge/chip.c
> >
> > so I want to avoid that.
> >
> > >
> > > > > Also, I'm not sure how your rework helps ARM (or any other
> > > > > architecture) people with their approach to ACPI enabling (most of the
> > > > > files are under x86).
> > > >
> > > > I kept x86-specific tables in the x86 directories. Of course I might
> > > > be wrong about this. But then, people who use ACPI on ARM (ick!)
> > >
> > > Haven't you seen the series to introduce ACPI for ARM in U-Boot recently?
> >
> > Yes, and that author is awaiting us getting this series in so that he
> > can build on it.
>
> Good that we aware.

Yes.

>
> > > > probably have a better idea on what is needed. The core DM support and
> > > > tests are there.
> > >
> > > I think with a such big rework it's not big deal to simple move it
> > > outside of arch/x86 to the lib/acpi or so.
> >
> > My intention was to put generic ACPI things in there though, not
> > x86-specific stuff. I assume that ARM would have its own stuff in
> > arch.arm
>
> Yes, that what I'm talking about. So we are on the same page here.

OK good.

Regards,
Simpon