linux-kernel - Re: [PATCH 3/3 V3] EDAC, AMD64_EDAC: Add ECC decoding support for newer F15h models.

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Date:	Fri, 9 Aug 2013 11:54:30 -0500
From:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
To:	Borislav Petkov <bp@...en8.de>
CC:	<tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
	<dougthompson@...ssion.com>, <bhelgaas@...gle.com>,
	<jbeulich@...e.com>, <linux-kernel@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, <linux-pci@...r.kernel.org>
Subject: Re: [PATCH 3/3 V3] EDAC, AMD64_EDAC: Add ECC decoding support for
 newer F15h models.

On 8/9/2013 8:18 AM, Borislav Petkov wrote:
>   	}
>   
> @@ -205,8 +209,9 @@ static int amd64_set_scrub_rate(struct mem_ctl_info *mci, u32 bw)
>   	if (boot_cpu_data.x86 == 0xf)
>   		min_scrubrate = 0x0;
>   
> -	/* F15h Erratum #505 */
> -	if (boot_cpu_data.x86 == 0x15)
> +	/* F15h Models 0x00 - 0x0f Erratum #505 */
> +	if (boot_cpu_data.x86 == 0x15 &&
> +		boot_cpu_data.x86_model != 0x30)
> This check leaves holes in the model space:
>
> You want:
>
> 		boot_cpu_data.x86_model < 0x30)
>
> provided everything below 0x30 is affected. But you say models 0x0-0xf
> are only affected, which means:
>
>
> 		boot_cpu_data.x86_model < 0x10)
>
> Please recheck which is it.
>
>>   		f15h_select_dct(pvt, 0);
>>   
>>   	return __amd64_set_scrub_rate(pvt->F3, bw, min_scrubrate);
>> @@ -218,8 +223,9 @@ static int amd64_get_scrub_rate(struct mem_ctl_info *mci)
>>   	u32 scrubval = 0;
>>   	int i, retval = -EINVAL;
>>   
>> -	/* F15h Erratum #505 */
>> -	if (boot_cpu_data.x86 == 0x15)
>> +	/* F15h Models 0x00 - 0x0f Erratum #505 */
>> +	if (boot_cpu_data.x86 == 0x15 &&
>> +		boot_cpu_data.x86_model != 0x30)
> Ditto.
Ok, So - from digging up some history about the bug, looks like this was
'fixed' on F15h Model1h Stepping 1 onwards.
I have now changed the code to only consider CPU's that are below (Model 
1 && Stepping 1)

> drivers/edac/amd64_edac.c: In function ‘f15_m30h_match_to_this_node’:
> drivers/edac/amd64_edac.c:1552:2: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
>
>> +	u8 dct_offset_en	= (u8) ((dct_cont_base_reg >> 3) & BIT(0));
>> +	u8 dct_sel		= (u8) ((dct_cont_base_reg >> 4) & 0x7);
>> +	u8 intlv_addr		= dct_sel_interleave_addr(pvt);
>> +	u8 node_id		= dram_dst_node(pvt, range);
>> +	u8 intlv_en		= dram_intlv_en(pvt, range);
>> +
>> +	edac_dbg(1, "(range %d) SystemAddr= 0x%llx Limit=0x%llx\n",
>> +		 range, sys_addr, get_dram_limit(pvt, range));
> …
>
> The rest looks ok.
>

Ok,
I have removed the compiler warnings now and function-tested it as well. 
(Works fine.)
Sending out changes in  [PATCH 3/3 V4]

Thanks,
-Aravind.

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