linux-kernel - Re: [PATCH 2/2] x86/quark: Add Quark embedded SRAM self-test

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Message-ID: <554A24BA.80605@nexus-software.ie>
Date:	Wed, 06 May 2015 07:27:06 -0700
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	Ingo Molnar <mingo2.kernel.org@...il.com>
CC:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, dvhart@...radead.org, andy.schevchenko@...il.com,
	boon.leong.ong@...el.com, linux-kernel@...r.kernel.org,
	platform-driver-x86@...r.kernel.org, derek.browne@...el.com,
	josef.ahmad@...el.com, erik.nyquist@...el.com
Subject: Re: [PATCH 2/2] x86/quark: Add Quark embedded SRAM self-test

On 06/05/15 03:02, Ingo Molnar wrote:

>> + * This function is carefully constructed to measure and verify the
>> + * performance boost provided by eSRAM. We invalidate the cache with a
>> + * wbinvd() and then perform a series of reads - each of which will cause a
>> + * cacheline miss. We measure the aggregate time it takes to complete the
>> + * series of reads and return the delta in cycles. The calling function will
>> + * pass either a pointer to DRAM or a pointer to eSRAM.
>> + *
>> + * @param walker:	Pointer to RAM area to test.
>> + * @return:		Number of cycles to complete test.
>> + */

<snip>

>
> So I don't see the wbinvd() that the description mentions.

wbinvd(); isn't required to make the test do it's job. Missed scrubbing 
from the description - damn :(

>
>> + * esram_self_test_init - entry point for IMR driver.
>> + * esram_self_test_exit - exit point for IMR code.
>
> Stale 'IMR' references left over from copy & paste?

Yep

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