linux-kernel - Re: [PATCH] Fix EDAC sdram_scrub

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Date:	Fri, 16 Sep 2011 14:53:27 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Han Pingtian <phan@...hat.com>
Cc:	mchehab@...hat.com, linux-kernel@...r.kernel.org,
	edac-devel <linux-edac@...r.kernel.org>
Subject: Re: [PATCH] Fix EDAC sdram_scrub_rate read failure

On Fri, Sep 16, 2011 at 06:58:56PM +0800, Han Pingtian wrote:
> If sdram scrubbing rate ins't implemented on current system, read it
> will cause an error:
> 
> cat: /sys/devices/system/edac/mc//mc0/sdram_scrub_rate: Invalid argument
> 
> The eba042a81edd6baaff44831b2d719b14a6d21e58 let it returning -EINVAL,

Can you please add the patch author to CC next time, out of courtesy?
Thanks.

> but according to the document, it should show -1:
> 
> dram memory scrubbing rate:
> 
>         'sdram_scrub_rate'
> 
>         Read/Write attribute file that controls memory scrubbing. The scrubbing
>         rate is set by writing a minimum bandwidth in bytes/sec to the attribute
>         file. The rate will be translated to an internal value that gives at
>         least the specified rate.
> 
>         Reading the file will return the actual scrubbing rate employed.
> 
>         If configuration fails or memory scrubbing is not implemented, the value
>         of the attribute file will be -1.
> 
> Signed-off-by: Han Pingtian <phan@...hat.com>
> ---
>  drivers/edac/edac_mc_sysfs.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
> index 29ffa35..602fdcf 100644
> --- a/drivers/edac/edac_mc_sysfs.c
> +++ b/drivers/edac/edac_mc_sysfs.c
> @@ -475,7 +475,7 @@ static ssize_t mci_sdram_scrub_rate_show(struct mem_ctl_info *mci, char *data)
>  	int bandwidth = 0;
>  
>  	if (!mci->get_sdram_scrub_rate)
> -		return -EINVAL;
> +		return sprintf(date, "%d\n", -1);

Have you even build-tested your patch:

drivers/edac/edac_mc_sysfs.c: In function ‘mci_sdram_scrub_rate_show’:
drivers/edac/edac_mc_sysfs.c:478: error: ‘date’ undeclared (first use in this function)
drivers/edac/edac_mc_sysfs.c:478: error: (Each undeclared identifier is reported only once
drivers/edac/edac_mc_sysfs.c:478: error: for each function it appears in.)
make[2]: *** [drivers/edac/edac_mc_sysfs.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [drivers/edac] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [drivers] Error 2
make: *** Waiting for unfinished jobs....

>  
>  	bandwidth = mci->get_sdram_scrub_rate(mci);
>  	if (bandwidth < 0) {

Anyway, the EDAC document says that sdram_scrub_rate is
read/write and when writing you have to write -1 too. Care to fix
mci_sdram_scrub_rate_store too, test your patch properly and resend?

Thanks.

-- 
Regards/Gruss,
Boris.

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