linux-kernel - Re: [PATCH v1 1/1] x86/platform/intel-mid: Run PWRMU command immediately

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Message-ID: <20160818105209.GB30771@gmail.com>
Date:	Thu, 18 Aug 2016 12:52:10 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] x86/platform/intel-mid: Run PWRMU command
 immediately


* Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On some firmwares we have to tell how exactly we want the command to be run.
> The default case for now is to run it immediately.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  arch/x86/platform/intel-mid/pwr.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/platform/intel-mid/pwr.c b/arch/x86/platform/intel-mid/pwr.c
> index c901a34..0548741 100644
> --- a/arch/x86/platform/intel-mid/pwr.c
> +++ b/arch/x86/platform/intel-mid/pwr.c
> @@ -44,6 +44,10 @@
>  /* Bits in PM_CMD */
>  #define PM_CMD_CMD(x)		((x) << 0)
>  #define PM_CMD_IOC		(1 << 8)
> +#define PM_CMD_CM_NOP		(0 << 9)
> +#define PM_CMD_CM_IMMEDIATE	(1 << 9)
> +#define PM_CMD_CM_DELAY		(2 << 9)
> +#define PM_CMD_CM_TRIGGER	(3 << 9)
>  #define PM_CMD_D3cold		(1 << 21)
>  
>  /* List of commands */
> @@ -137,7 +141,7 @@ static int mid_pwr_wait(struct mid_pwr *pwr)
>  
>  static int mid_pwr_wait_for_cmd(struct mid_pwr *pwr, u8 cmd)
>  {
> -	writel(PM_CMD_CMD(cmd), pwr->regs + PM_CMD);
> +	writel(PM_CMD_CMD(cmd) | PM_CMD_CM_IMMEDIATE, pwr->regs + PM_CMD);
>  	return mid_pwr_wait(pwr);
>  }

Does this fix a bug? If yes then please also add that to the changelog: what are 
the symptoms of the bug - how does a user notice, etc.

Thanks,

	Ingo