Re: [PATCH 1/3] pci: determine CLS more intelligently

From: Jesse Barnes
Date: Thu Sep 17 2009 - 13:31:47 EST


On Sat, 04 Jul 2009 14:08:57 +0900
Tejun Heo <tj@xxxxxxxxxx> wrote:

> Till now, CLS has been determined either by arch code or as
> L1_CACHE_BYTES. Only x86 and ia64 set CLS explicitly and x86 doesn't
> always get it right. On most configurations, the chance is that
> firmware configures the correct value during boot.
>
> This patch makes pci_init() determine CLS by looking at what firmware
> has configured. It scans all devices and if all non-zero values
> agree, the value is used. If none is configured or there is a
> disagreement, pci_dfl_cache_line_size is used. arch can set the dfl
> value (via PCI_CACHE_LINE_BYTES or pci_dfl_cache_line_size) or
> override the actual one.
>
> ia64, x86 and sparc64 updated to set the default cls instead of the
> actual one.
>
> While at it, declare pci_cache_line_size and pci_dfl_cache_line_size
> in pci.h and drop private declarations from arch code.

This sounds like a good improvement (though I share Ingo's concerns
about platform breakage here). Can you respin the patchset against my
linux-next current tree?

Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
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