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

From: Jia Hongtao-B38951 <hidden>
Date: 2012-06-12 02:25:00

-----Original Message-----
From: Bhushan Bharat-R65777
Sent: Monday, June 11, 2012 9:25 PM
To: Jia Hongtao-B38951; linuxppc-dev@lists.ozlabs.org;
galak@kernel.crashing.org
Cc: Li Yang-R58472; benh@kernel.crashing.org; Wood Scott-B07421
Subject: RE: [PATCH 0/6] Description for PCI patches using platform
driver
=20
=20
=20

quoted

-----Original Message-----
From: Jia Hongtao-B38951
Sent: Monday, June 11, 2012 8:03 AM
To: Bhushan Bharat-R65777; linuxppc-dev@lists.ozlabs.org;
galak@kernel.crashing.org
Cc: Li Yang-R58472; benh@kernel.crashing.org; Wood Scott-B07421
Subject: RE: [PATCH 0/6] Description for PCI patches using platform

driver

quoted

-----Original Message-----
From: Bhushan Bharat-R65777
Sent: Friday, June 08, 2012 6:47 PM
To: Jia Hongtao-B38951; linuxppc-dev@lists.ozlabs.org;
galak@kernel.crashing.org
Cc: Li Yang-R58472; benh@kernel.crashing.org; Wood Scott-B07421
Subject: RE: [PATCH 0/6] Description for PCI patches using platform
driver

quoted

-----Original Message-----
From: Jia Hongtao-B38951
Sent: Friday, June 08, 2012 3:12 PM
To: linuxppc-dev@lists.ozlabs.org; galak@kernel.crashing.org
Cc: Li Yang-R58472; benh@kernel.crashing.org; Wood Scott-B07421;

Bhushan Bharat-

quoted

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

quoted

for all 85xx/86xx powerpc boards. But two side effects are
introduced

by this

quoted

mechanism which listed below:

1. of_platform_bus_probe() will be called twice but in some cases

duplication

quoted

   warning occured. We fix this in [PATCH 5/6].

2. Edac driver failed to register pci nodes as platform devices. We
fix

this

quoted

   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

quoted

only demanded by PCI/PCIe. One of the purposes of sending out these

patches is

quoted

to let us start a discussion for this problem in upstream.

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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.
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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 :).
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Following are the solutions we have thought of during our internal
discussions (if I did not missed any):
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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.
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2. All known devices, the lowest PCIe outbound range starts at 0x80000000=

quoted hunk ↗ jump to hunk

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.
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Something like this:
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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

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#ifdef CONFIG_SWIOTLB
-       if (memblock_end_of_DRAM() > 0xffffffff)
+       if (memblock_end_of_DRAM() > 0xff000000)
                 ppc_swiotlb_enable =3D 1;  #endif
         pr_info("%s board from Freescale Semiconductor\n", ppc_md.name);
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-------------
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3. Always do swiotlb_init() in mem_init() and later after PCI init, if
the swiotlb is not needed then free it (swiotlb_free()).
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4. etc, please provide some other better way.
=20
Thanks
-Bharat

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

-Jia Hongtao.

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