linux-kernel - RE: [RFC PATCH 0/4] Add ACPI support for HiSilicon PCIe Host Controllers

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Date:	Mon, 8 Feb 2016 13:17:58 +0000
From:	Gabriele Paoloni <gabriele.paoloni@...wei.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	"Guohanjun (Hanjun Guo)" <guohanjun@...wei.com>,
	"Wangzhou (B)" <wangzhou1@...ilicon.com>,
	"liudongdong (C)" <liudongdong3@...wei.com>,
	Linuxarm <linuxarm@...wei.com>, qiujiang <qiujiang@...wei.com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"Lorenzo.Pieralisi@....com" <Lorenzo.Pieralisi@....com>,
	"tn@...ihalf.com" <tn@...ihalf.com>,
	zhangjukuo <zhangjukuo@...wei.com>,
	"xuwei (O)" <xuwei5@...ilicon.com>,
	"Liguozhu (Kenneth)" <liguozhu@...ilicon.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jcm@...hat.com" <jcm@...hat.com>
Subject: RE: [RFC PATCH 0/4] Add ACPI support for HiSilicon PCIe Host
 Controllers

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@...db.de]
> Sent: 04 February 2016 17:02
> To: Gabriele Paoloni
> Cc: Guohanjun (Hanjun Guo); Wangzhou (B); liudongdong (C); Linuxarm;
> qiujiang; bhelgaas@...gle.com; Lorenzo.Pieralisi@....com;
> tn@...ihalf.com; zhangjukuo; xuwei (O); Liguozhu (Kenneth); linux-
> pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
> acpi@...r.kernel.org; linux-kernel@...r.kernel.org; jcm@...hat.com
> Subject: Re: [RFC PATCH 0/4] Add ACPI support for HiSilicon PCIe Host
> Controllers
> 
> On Thursday 04 February 2016 16:44:12 Gabriele Paoloni wrote:
> > Effectively the ACPI version of the HiSilicon driver does not rely on
> > Designware as much as the DT version (that calls
> dw_pcie_host_init());
> > however in order to do what you suggest I'd need to copy and paste
> and
> > modify dw_pcie_rd_conf and dw_pcie_wr_conf.
> > Also I'd need to declare duplicate version of the functions in
> > pcie-hisi-common.c (if I do not want to split the object across
> > different paths "drivers/pci/host" and "drivers/acpi/")
> >
> > Now I can do it but I thought it was more correct to pass
> &dw_pcie_ops
> > as input pointer in DECLARE_ACPI_MCFG_FIXUP(); this is also because
> maybe in
> > future other Designware based controllers may need to support ACPI
> and it
> > would be easier for them to reuse their DT based driver functions
> >
> > Honestly I am a bit confused...
> >
> 
> I don't think you can use the dw_pcie_ops as-is anyway, as they in
> turn rely on the device driver structure, and you also don't need
> those as they seem to be written for the generic case of a 32-bit
> architecture that does not have enough space to map the entire
> config space into MMIO. Just set up all those mapping registers from
> the firmware and pass the config space base address as you'd normally
> do on ACPI.

Hi Arnd

I have now sent out patchset v2.

Now I have removed the dependency from designware but I still think
the best location for the code is in "drivers/pci/host/":
the ACPI quirks share the config read/write functions with the DT
driver, moreover for other hosts in future I think it makes sense
to stay in "drivers/pci/host/" as they could even share more init
code with their respective DT versions...

Cheers

Gab

> 
> 	Arnd