linux-kernel - Re: [PATCH v6 4/7] ARM: l2c: Add support for overriding prefetch settings

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Message-ID: <20141028113531.GZ12379@n2100.arm.linux.org.uk>
Date:	Tue, 28 Oct 2014 11:35:31 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	Tomasz Figa <tomasz.figa@...il.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>, lauraa@...eaurora.org,
	linux-omap@...r.kernel.org, linus.walleij@...aro.org,
	santosh.shilimkar@...com, tony@...mide.com, drake@...lessm.com,
	loeliger@...il.com, Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v6 4/7] ARM: l2c: Add support for overriding prefetch
	settings

On Mon, Oct 27, 2014 at 12:19:34PM +0100, Marek Szyprowski wrote:
> Hello,
>
> On 2014-10-27 12:14, Russell King - ARM Linux wrote:
>> On Mon, Oct 27, 2014 at 12:05:47PM +0100, Marek Szyprowski wrote:
>>> From: Tomasz Figa <t.figa@...sung.com>
>>>
>>> Firmware on certain boards (e.g. ODROID-U3) can leave incorrect L2C prefetch
>>> settings configured in registers leading to crashes if L2C is enabled
>>> without overriding them. This patch introduces bindings to enable
>>> prefetch settings to be specified from DT and necessary support in the
>>> driver.
>>>
>>> Signed-off-by: Tomasz Figa <t.figa@...sung.com>
>>> [mszyprow: rebased onto v3.18-rc1, added error messages when property value
>>>   is missing]
>> Why?  What if the boot loader has already set these up appropriately?  Why
>> should we force people to list these in the DT?
>
> The error message is displayed only when user provided prefetch related
> properties without any value (empty properties). Something that Mark Rutland
> requested here: https://lkml.org/lkml/2014/9/24/426 I'm sorry if I didn't
> describe it clearly enough.

Ok.

I'd ask for one change.  Please make all these messages start with
"L2C-310 OF" not "PL310 OF:".  The device is described in ARM
documentation as a L2C-310 not PL310.  (Also note the : is dropped
too - most of the other messages don't have the : either.)

The:

"PL310 OF: cache setting yield illegal associativity
PL310 OF: -1073346556 calculated, only 8 and 16 legal"

message could also be changed to something like:

"L2C-310 OF cache associativity %d invalid, only 8 or 16 permitted\n"

Thanks.

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