linux-kernel - Re: [PATCH v2] PCI: designware: move remaining rc setup code to dw_pcie_setup

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Message-ID: <CAHM4w1kKmbkWoeMzKXgu+wMW+O2e5=wFe=WrKn_HLcFv4s_Qcg@mail.gmail.com>
Date:	Thu, 14 Apr 2016 18:38:09 +0530
From:	Pratyush Anand <pratyush.anand@...il.com>
To:	Jingoo Han <jingoohan1@...il.com>,
	Gabriele Paoloni <gabriele.paoloni@...wei.com>
Cc:	Bjorn Helgaas <helgaas@...nel.org>,
	Jisheng Zhang <jszhang@...vell.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	linux-kernel@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2] PCI: designware: move remaining rc setup code to dw_pcie_setup_rc()

Hi Gabriele,

On Thu, Apr 14, 2016 at 5:22 PM, Jingoo Han <jingoohan1@...il.com> wrote:
> On Wednesday, April 13, 2016 4:58 PM, Gabriele Paoloni wrote:
>>
>> Hi Jingoo
>>
>> On 13 April 2016 06:52, Jingoo Han wrote:
>> > On Tuesday, April 12, 2016 6:44 PM, Gabriele Paoloni wrote:

[...]

>> > > So I will update the driver to call dw_pcie_setup_rc() from
>> > > .host_init and ask the BIOS team to update the firmware for next
>> > > releases (the driver will be backward compatible anyway).
>> > >
>> > > Also during my investigation I have noticed that in
>> > dw_pcie_setup_rc()
>> > > http://lxr.free-electrons.com/source/drivers/pci/host/pcie-
>> > designware.c#L762
>> > >
>> > > we use pp->mem_base rather than pp->mem_bus_addr to setup
>> > > memory base and memory limit in the Type1 header...I think this
>> > > is wrong right?

Yes. RC's "memory base" and "memory limit" should be governed by PCI
addresses and not CPU addresses. So, it should use pp->mem_bus_addr.

>> > > Also I do not see why this code is needed at all since we overwrite
>> > > this register when we call pci_bus_assign_resources(bus) that
>> > > will end up in calling pci_setup_bridge() and then
>> > > pci_setup_bridge_mmio()...?
>>
>> Do you have any comment on this issue above?

Probably thats why things are working.
Thanks for finding it. I think, /* setup memory base, memory limit */
hunk can be removed from dw_pcie_setup_rc.

~Pratyush