Hi Arnd, Sinan

-----Original Message-----
From: Sinan Kaya [mailto:okaya at codeaurora.org]
Sent: 08 February 2016 14:12
To: Arnd Bergmann; linux-arm-kernel at lists.infradead.org
Cc: Gabriele Paoloni; Lorenzo.Pieralisi at arm.com; jcm at redhat.com;
tn at semihalf.com; linux-pci at vger.kernel.org; Linuxarm; xuwei (O); linux-
kernel at vger.kernel.org; linux-acpi at vger.kernel.org; Wangzhou (B);
liudongdong (C); Guohanjun (Hanjun Guo); bhelgaas at google.com;
zhangjukuo; Liguozhu (Kenneth); qiujiang
Subject: Re: [RFC PATCH 0/4] Add ACPI support for HiSilicon PCIe Host
Controllers

On 2/8/2016 8:55 AM, Arnd Bergmann wrote:

quoted

I haven't really followed what is going on with ACPI. Do you expect
to see future machines come out that are not just implementing SBSA
but that still need to run ACPI? I thought this was just a hack
for some early machines that only run with ACPI but are not actually
compliant.

Well from our side (HiSilicon) we're trying to move away from non fully 
ECAM platforms, so from us in the long term I don't expect too many quirks,
but I don't know about the other vendors.

Obviously the reason why Tomasz implemented the quirks is to fit non 
fully ECAM HW and to allow custom HW init; this is why I thought better
to have the ACPI version in the same dir as the DT (maybe we can create 
an ACPI sub-dir in drivers/pci/host ?)

quoted

	Arnd

I agree. We shouldn't be playing with half-baked ACPI solutions. We
have seen
two variants already that claim to be ACPI compliant yet they do not
tie into
anything inside ACPICA.

The correct route is to use Tomasz's ACPI PCI root bridge driver and
use the ACPI
framework.

If a platform has quirks, Tomasz's patches allow vendors add quirks
too.

The combination of PCI host bridge driver + ACPI hack is not right.

If you look at my patchset  you can see that I didn't do any hack,

I just used the framework provided by Tomasz patchset.

The discussion here is more about the code location for the quirks.
Since the configuration read/write and the HW init sequences can be
similar between the ACPI variant and DT variant I thought it make 
sense to have them in "drivers/pci/host"

Thanks

Gab

--
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center,
Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project