linux-kernel - Re: [PATCH] [1/5] Only do century BCD conversion when we know the RTC is BCD

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Date:	Mon, 11 Feb 2008 09:30:05 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andi Kleen <ak@...e.de>
cc:	mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [1/5] Only do century BCD conversion when we know the
 RTC is BCD

On Sat, 9 Feb 2008, Andi Kleen wrote:

> 
> Minor logic fix. The century change was previously always BCD,
> even when the CMOS data would report itself not being BCD.

I checked that whole rtc / BCD logic again. We always set RTC_ALWAYS_BCD:

#ifndef RTC_PORT
#define RTC_PORT(x)    (0x70 + (x))
#define RTC_ALWAYS_BCD 1       /* RTC operates in BCD mode */
#endif

Nothing ever defines RTC_PORT and RTC_ALWAYS_BCD

So we can get rid of that stuff completely.

> Signed-off-by: Andi Kleen <ak@...e.de>
> 
> ---
>  arch/x86/kernel/rtc.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux/arch/x86/kernel/rtc.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/rtc.c
> +++ linux/arch/x86/kernel/rtc.c
> @@ -130,10 +130,10 @@ unsigned long mach_get_cmos_time(void)
>  		BCD_TO_BIN(day);
>  		BCD_TO_BIN(mon);
>  		BCD_TO_BIN(year);
> +		BCD_TO_BIN(century);

This should probably go here:

        if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
            acpi_gbl_FADT.century) {
--->
 	}

It does not matter much, because BCD_TO_BIN(0) is 0, but it makes a
lot of sense.

Thanks,

	tglx
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