RE: [PATCH v11 1/6] PCI: designware: move calculation of bus addresses to DRA7xx

[Gabriele Paoloni]

> -----Original Message-----
> From: linux-pci-owner@xxxxxxxxxxxxxxx [mailto:linux-pci-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Bjorn Helgaas
> Sent: Thursday, October 22, 2015 5:36 PM
> To: Gabriele Paoloni
> Cc: Wangzhou (B); Bjorn Helgaas; jingoohan1@xxxxxxxxx;
> pratyush.anand@xxxxxxxxx; Arnd Bergmann; linux@xxxxxxxxxxxxxxxx;
> thomas.petazzoni@xxxxxxxxxxxxxxxxxx; lorenzo.pieralisi@xxxxxxx;
> james.morse@xxxxxxx; Liviu.Dudau@xxxxxxx; jason@xxxxxxxxxxxxxx;
> robh@xxxxxxxxxx; gabriel.fernandez@xxxxxxxxxx;
> Minghuan.Lian@xxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; zhangjukuo; qiuzhenfa; liudongdong (C);
> qiujiang; xuwei (O); Liguozhu (Kenneth)
> Subject: Re: [PATCH v11 1/6] PCI: designware: move calculation of bus
> addresses to DRA7xx
> 
> Hi Gabriele,
> 
> On Thu, Oct 22, 2015 at 07:21:41AM +0000, Gabriele Paoloni wrote:
> > > -----Original Message-----
> > > From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx]
> 
> > > >  #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.

Great Many Thanks for this!

Gab

> 
> Bjorn
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