linux-kernel - Re: [PATCH v1] platform/x86: intel_pmc

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Date:   Fri, 10 Feb 2017 09:54:00 +0530
From:   Rajneesh Bhardwaj <rajneesh.bhardwaj@...el.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        Shanth Murthy <shanth.murthy@...el.com>,
        Zha Qipeng <qipeng.zha@...el.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>
Subject: Re: [PATCH v1] platform/x86: intel_pmc_ipc: fix division in 32-bit
 case

On Wed, Feb 08, 2017 at 06:00:28PM +0200, Andy Shevchenko wrote:
> On 32-bit x86 platforms we can't do 64-bit divisions:
> 
> 	ERROR: "__udivdi3" [drivers/platform/x86/intel_pmc_ipc.ko] undefined!
> 
> Replace plain division by do_div() macro call.
> 
> Reported-by: Darren Hart <dvhart@...radead.org>
> Cc: Shanth Murthy <shanth.murthy@...el.com>
> Cc: Rajneesh Bhardwaj <rajneesh.bhardwaj@...el.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/platform/x86/intel_pmc_ipc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel_pmc_ipc.c b/drivers/platform/x86/intel_pmc_ipc.c
> index 46202b6e7c87..8ad4d7b43423 100644
> --- a/drivers/platform/x86/intel_pmc_ipc.c
> +++ b/drivers/platform/x86/intel_pmc_ipc.c
> @@ -62,7 +62,12 @@
>  #define GCR_TELEM_SHLW_S0IX_OFFSET	0x1080
>  
>  /* Residency with clock rate at 19.2MHz to usecs */
> -#define S0IX_RESIDENCY_IN_USECS(d, s)		(((d) + (s)) * 10 / 192)
> +#define S0IX_RESIDENCY_IN_USECS(d, s)		\
> +({						\
> +	u64 result = 10ull * ((d) + (s));	\
> +	do_div(result, 192);			\
> +	result;					\
> +})
> 

Looks good, we verified it. We are planning to squash this one and send V2.
Hope thats fine?
 
>  /*
>   * 16-byte buffer for sending data associated with IPC command.
> -- 
> 2.11.0
> 

-- 
Best Regards,
Rajneesh