[PATCH 0/6] Description for PCI patches using platform driver

[Jia Hongtao-B38951]

> -----Original Message-----
> From: Bhushan Bharat-R65777
> Sent: Monday, June 11, 2012 9:25 PM
> To: Jia Hongtao-B38951; linuxppc-dev at lists.ozlabs.org;
> galak at kernel.crashing.org
> Cc: Li Yang-R58472; benh at kernel.crashing.org; Wood Scott-B07421
> Subject: RE: [PATCH 0/6] Description for PCI patches using platform
> driver
> 
> 
> 
> > -----Original Message-----
> > From: Jia Hongtao-B38951
> > Sent: Monday, June 11, 2012 8:03 AM
> > To: Bhushan Bharat-R65777; linuxppc-dev at lists.ozlabs.org;
> > galak at kernel.crashing.org
> > Cc: Li Yang-R58472; benh at kernel.crashing.org; Wood Scott-B07421
> > Subject: RE: [PATCH 0/6] Description for PCI patches using platform
> driver
> >
> > > -----Original Message-----
> > > From: Bhushan Bharat-R65777
> > > Sent: Friday, June 08, 2012 6:47 PM
> > > To: Jia Hongtao-B38951; linuxppc-dev at lists.ozlabs.org;
> > > galak at kernel.crashing.org
> > > Cc: Li Yang-R58472; benh at kernel.crashing.org; Wood Scott-B07421
> > > Subject: RE: [PATCH 0/6] Description for PCI patches using platform
> > > driver
> > >
> > >
> > > > -----Original Message-----
> > > > From: Jia Hongtao-B38951
> > > > Sent: Friday, June 08, 2012 3:12 PM
> > > > To: linuxppc-dev at lists.ozlabs.org; galak at kernel.crashing.org
> > > > Cc: Li Yang-R58472; benh at kernel.crashing.org; Wood Scott-B07421;
> > > Bhushan Bharat-
> > > > R65777; Jia Hongtao-B38951
> > > > Subject: [PATCH 0/6] Description for PCI patches using platform
> > > > driver
> > > >
> > > > This series of patches are to unify pci initialization code and add
> > > > PM
> > > support
> > > > for all 85xx/86xx powerpc boards. But two side effects are
> > > > introduced
> > > by this
> > > > mechanism which listed below:
> > > >
> > > > 1. of_platform_bus_probe() will be called twice but in some cases
> > > duplication
> > > >    warning occured. We fix this in [PATCH 5/6].
> > > >
> > > > 2. Edac driver failed to register pci nodes as platform devices. We
> > > > fix
> > > this
> > > >    in [PATCH 6/6].
> > >
> > > With these patches will not the SWIOTLB will not be initialized even
> > > if PCI/PCIe demanded?
> > >
> > > Thanks
> > > -Bharat
> > >
> >
> > These patches still have the swiotlb init problem if
> "ppc_swiotlb_enable" is
> > only demanded by PCI/PCIe. One of the purposes of sending out these
> patches is
> > to let us start a discussion for this problem in upstream.
> 
> Ok, I did not find any mention of that, so I thought that you have
> resolved the issue by some means in these patches which I did not catch.
> 
> So, these patches introduces the issue, that SWIOTLB will not be
> initialized if requested by pci/pcie. The request is raised by setting
> the flag ppc_swiotlb_enable. The swiotlb_init() will be called in
> mem_init() if ppc_swiotlb_enable is set. Now with these patches, the
> request is raised after mem_init() is called. So request not handled :).
> 
> Following are the solutions we have thought of during our internal
> discussions (if I did not missed any):
> 
> 1. These patches move the code from platform init to device init
> (arch_initcall()). Rather than moving the whole code, let us divide the
> code into two. First, which is needed to raise the swiotlb init request
> and second the rest. Define this first as an function in
> arch/powerpc/sysdev/fsl_pci.c and call this from platform init code of
> the SOCs.
> 
> 2. All known devices, the lowest PCIe outbound range starts at 0x80000000,
> but there's nothing above 0xc0000000. So the inbound of size 0x8000_0000
> is always availbe on all devices. Hardcode the check in platform code to
> check memblock_end_of_DRAM() to 0x80000000.
> 
> Something like this:
> 
> diff --git a/arch/powerpc/platforms/85xx/corenet_ds.c
> b/arch/powerpc/platforms/85xx/corenet_ds.c
> index 1f7028e..ef4e215 100644
> --- a/arch/powerpc/platforms/85xx/corenet_ds.c
> +++ b/arch/powerpc/platforms/85xx/corenet_ds.c
> @@ -79,7 +79,7 @@ void __init corenet_ds_setup_arch(void)  #endif
> 
> #ifdef CONFIG_SWIOTLB
> -       if (memblock_end_of_DRAM() > 0xffffffff)
> +       if (memblock_end_of_DRAM() > 0xff000000)
>                  ppc_swiotlb_enable = 1;  #endif
>          pr_info("%s board from Freescale Semiconductor\n", ppc_md.name);
> 
> -------------
> 
> 3. Always do swiotlb_init() in mem_init() and later after PCI init, if
> the swiotlb is not needed then free it (swiotlb_free()).
> 
> 4. etc, please provide some other better way.
> 
> Thanks
> -Bharat

Thanks.
In my point of view the 2nd solution is better for it does not treat PCI/PCIe as
the special kind of devices from others.

-Jia Hongtao.