linux-kernel - Re: [PATCH v11 1/6] PCI: designware: move calculation of bus addresses to DRA7xx

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Message-ID: <562DD5D2.9000705@hisilicon.com>
Date:	Mon, 26 Oct 2015 15:27:14 +0800
From:	Zhou Wang <wangzhou1@...ilicon.com>
To:	Bjorn Helgaas <helgaas@...nel.org>
CC:	Gabriele Paoloni <gabriele.paoloni@...wei.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"jingoohan1@...il.com" <jingoohan1@...il.com>,
	"pratyush.anand@...il.com" <pratyush.anand@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"thomas.petazzoni@...e-electrons.com" 
	<thomas.petazzoni@...e-electrons.com>,
	"lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
	"james.morse@....com" <james.morse@....com>,
	"Liviu.Dudau@....com" <Liviu.Dudau@....com>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"robh@...nel.org" <robh@...nel.org>,
	"gabriel.fernandez@...aro.org" <gabriel.fernandez@...aro.org>,
	"Minghuan.Lian@...escale.com" <Minghuan.Lian@...escale.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	zhangjukuo <zhangjukuo@...wei.com>,
	qiuzhenfa <qiuzhenfa@...ilicon.com>,
	"liudongdong (C)" <liudongdong3@...wei.com>,
	qiujiang <qiujiang@...wei.com>,
	"xuwei (O)" <xuwei5@...ilicon.com>,
	"Liguozhu (Kenneth)" <liguozhu@...ilicon.com>
Subject: Re: [PATCH v11 1/6] PCI: designware: move calculation of bus addresses
 to DRA7xx

On 2015/10/23 0:35, Bjorn Helgaas wrote:
> Hi Gabriele,
> 
> On Thu, Oct 22, 2015 at 07:21:41AM +0000, Gabriele Paoloni wrote:
>>> -----Original Message-----
>>> From: Bjorn Helgaas [mailto:helgaas@...nel.org]
> 
>>>>  #define	PCIECTRL_DRA7XX_CONF_PHY_CS			0x010C
>>>>  #define	LINK_UP						BIT(16)
>>>> +#define	CPU_TO_BUS_ADDR					0x0FFFFFFF
>>>
>>> "CPU_TO_BUS_ADDR" is a very generic name.  Since you do have DRA7XX in
>>> other #defines and static symbols in this file, maybe it could be DRA7XX to
>>> make it obvious that it only applies here?
>>
>> Ok will change to DRA7XX_CPU_TO_BUS_ADRR in v12
>> ..
> 
>>>> +	if (pp->io_mod_base)
>>>> +		pp->io_mod_base &= CPU_TO_BUS_ADDR;
>>>
>>> These are equivalent to
>>>
>>>   pp->io_mod_base &= CPU_TO_BUS_ADDR;
>>>
>>> (You don't need to test whether they're zero first.)
>>
>> Yes agreed, will change in v12
>> ...
> 
>>>>  	cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");
>>>> @@ -415,8 +411,7 @@ int dw_pcie_host_init(struct pcie_port *pp)
>>>>  			pp->io_base = range.cpu_addr;
>>>>
>>>>  			/* Find the untranslated IO space address */
>>>> -			pp->io_mod_base = of_read_number(parser.range -
>>>> -							 parser.np + na, ns);
>>>> +			pp->io_mod_base = range.cpu_addr;
>>>
>>> So apparently
>>>
>>>   "of_read_number() == range.cpu_addr & CPU_TO_BUS_ADDR" on DRA7xx
>>>   "of_read_number() == range.cpu_addr" everywhere else?
>>
>> Yes correct
>>
>>> Is that right?  Is that a valid assumption, i.e., are we assuming
>>> anything about DTs in the field that we shouldn't?
>>
>> Before I wrote a patch that was generic to accommodate intermediate level
>> of translation between PCI_addr -> BUS_addr -> CPU_addr
>>
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/360922.html
>>
>> After discussion we agreed to solve it with a bitmask rather than adding
>> a field to of_pci_range to make it generic.
>> The bitmask only applies to DRA7xx
> 
> I haven't gotten all the way through this series yet, but don't bother with
> a v12 just for these minor changes.  I can easily fix them up when applying
> it.
> 
> Bjorn
>

Hi Gabriele and Bjorn,

Sorry for late, I am preparing v12 patchset and I will fix above problems together
with other patches.

Many thanks,
Zhou

> .
> 


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