linux-kernel - Re: [PATCH 3/3] coretemp: Get microcode revision from cpu

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Date:	Wed, 25 May 2011 22:53:59 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>, jbeulich@...ell.com,
	fenghua.yu@...el.com
Subject: Re: [PATCH 3/3] coretemp: Get microcode revision from cpu_data v2

Hi Andi,

On Wed, 25 May 2011 12:32:28 -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> Now that the ucode revision is available in cpu_data remove
> the existing code in coretemp.c to query it manually. Read the ucode
> revision from cpu_data instead

Where is this available? Not upstream yet, apparently. I get a build
failure here.

> 
> v2: Fix misplaced variable init. Remove unused variables.
> Cc: jbeulich@...ell.com
> Cc: fenghua.yu@...el.com
> Cc: khali@...ux-fr.org
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  drivers/hwmon/coretemp.c |   31 +++++--------------------------
>  1 files changed, 5 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
> index 9577c43..eec29d6 100644
> --- a/drivers/hwmon/coretemp.c
> +++ b/drivers/hwmon/coretemp.c
> @@ -324,15 +324,6 @@ static int get_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *dev)
>  	}
>  }
>  
> -static void __devinit get_ucode_rev_on_cpu(void *edx)
> -{
> -	u32 eax;
> -
> -	wrmsr(MSR_IA32_UCODE_REV, 0, 0);
> -	sync_core();
> -	rdmsr(MSR_IA32_UCODE_REV, eax, *(u32 *)edx);
> -}
> -
>  static int get_pkg_tjmax(unsigned int cpu, struct device *dev)
>  {
>  	int err;
> @@ -425,29 +416,17 @@ static void update_ttarget(__u8 cpu_model, struct temp_data *tdata,
>  static int chk_ucode_version(struct platform_device *pdev)
>  {
>  	struct cpuinfo_x86 *c = &cpu_data(pdev->id);
> -	int err;
> -	u32 edx;
>  
>  	/*
>  	 * Check if we have problem with errata AE18 of Core processors:
>  	 * Readings might stop update when processor visited too deep sleep,
>  	 * fixed for stepping D0 (6EC).
>  	 */
> -	if (c->x86_model == 0xe && c->x86_mask < 0xc) {
> -		/* check for microcode update */
> -		err = smp_call_function_single(pdev->id, get_ucode_rev_on_cpu,
> -					       &edx, 1);

As a side note, this is fixing a section mismatch, as
get_ucode_rev_on_cpu() was declared __devinit but chk_ucode_version()
isn't. Thankfully this doesn't affect previous kernels. As far as I can
see, chk_ucode_version could be made __devinit. I'll send a patch.

> -		if (err) {
> -			dev_err(&pdev->dev,
> -				"Cannot determine microcode revision of "
> -				"CPU#%u (%d)!\n", pdev->id, err);
> -			return -ENODEV;
> -		} else if (edx < 0x39) {
> -			dev_err(&pdev->dev,
> -				"Errata AE18 not fixed, update BIOS or "
> -				"microcode of the CPU!\n");
> -			return -ENODEV;
> -		}
> +	if (c->x86_model == 0xe && c->x86_mask < 0xc && c->cpu_update < 0x39) {
> +		dev_err(&pdev->dev,
> +			"Errata AE18 not fixed, update BIOS or "
> +			"microcode of the CPU!\n");
> +		return -ENODEV;
>  	}
>  	return 0;
>  }

This all looks reasonable, but I am not able to test it.

-- 
Jean Delvare
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