From: Ingo Molnar <mingo@elte.hu>
To: Tejun Heo <tj@kernel.org>
Cc: Greg KH <greg@kroah.com>, Robert Hancock <hancockr@shaw.ca>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-pci@vger.kernel.org,
Linux Kernel <linux-kernel@vger.kernel.org>,
Daniel Ritz <daniel.ritz@gmx.ch>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
Axel Birndt <towerlexa@gmx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH 1/3] pci: determine CLS more intelligently
Date: Sat, 4 Jul 2009 11:29:56 +0200 [thread overview]
Message-ID: <20090704092956.GA26456@elte.hu> (raw)
In-Reply-To: <4A4EE3E9.7090205@kernel.org>
* Tejun Heo <tj@kernel.org> 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.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Acked-by: David Miller <davem@davemloft.net>
> Acked-by: Greg KH <gregkh@suse.de>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Tony Luck <tony.luck@intel.com>
The principle looks good to me. Regressions could be expected though
- these details are fragile and affect the way how we talk to
hardware.
Acked-by: Ingo Molnar <mingo@elte.hu>
Ingo
next prev parent reply other threads:[~2009-07-04 9:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-04 5:08 [PATCH 1/3] pci: determine CLS more intelligently Tejun Heo
2009-07-04 5:09 ` [PATCH 2/3] pci,sparc64: drop PCI_CACHE_LINE_BYTES Tejun Heo
2009-07-04 5:10 ` [PATCH 3/3] pccard: configure CLS on attach Tejun Heo
2009-07-04 9:29 ` Ingo Molnar [this message]
2009-09-17 17:31 ` [PATCH 1/3] pci: determine CLS more intelligently Jesse Barnes
2009-09-22 8:33 ` [PATCH 1/3 pci#linux-next] " Tejun Heo
2009-09-23 5:24 ` Benjamin Herrenschmidt
2009-10-06 16:53 ` Jesse Barnes
2009-09-22 8:34 ` [PATCH 2/3 pci#linux-next] pci,sparc64: drop PCI_CACHE_LINE_BYTES Tejun Heo
2009-09-22 8:34 ` [PATCH 3/3 pci#linux-next] pccard: configure CLS on attach Tejun Heo
2009-09-22 10:02 ` Axel Birndt
2009-09-23 1:18 ` Tejun Heo
2009-09-23 5:28 ` Benjamin Herrenschmidt
2009-09-28 17:52 ` [PATCH 1/3] pci: determine CLS more intelligently Jesse Barnes
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