linux-kernel - Re: [PATCH v2] ACPI: Leave Bus Master Arbitration enabled for suspend/resume

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Date:	Sun, 8 Jul 2012 22:08:19 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jonathan Nieder <jrnieder@...il.com>,
	Bob Moore <robert.moore@...el.com>
Cc:	Octavio Alvarez <alvarezp@...arezp.com>,
	Adrian Knoth <adi@...omp.erfurt.thur.de>,
	Shaohua Li <shli@...nel.org>, Len Brown <len.brown@...el.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ACPI: Leave Bus Master Arbitration enabled for suspend/resume

On Sunday, July 08, 2012, Jonathan Nieder wrote:
> This is an old suspend/resume lockup fix:
> 
> 	commit 2780cc4660e1
> 	Author: Len Brown <len.brown@...el.com>
> 	Date:   Thu Dec 23 13:43:30 2004 -0500
> 
> 	    [ACPI] Fix suspend/resume lockup issue
> 	    by leaving Bus Master Arbitration enabled.
> 	    The ACPI spec mandates it be disabled only for C3.
> 
> 	    http://bugzilla.kernel.org/show_bug.cgi?id=3599
> 
> 	    Signed-off-by: David Shaohua Li <shaohua.li@...el.com>
> 	    Signed-off-by: Len Brown <len.brown@...el.com>
> 
> The bug snuck back in in commit 2feec47d4c5f (ACPICA: ACPI 5: Support
> for new FADT SleepStatus, SleepControl registers, 2012-02-14),
> presumably by copy/pasting a copy of the code without that fix for the
> legacy case.
> 
> On affected machines, after that commit, the machine locks up hard on
> resume from suspend.  The same fix as seven years ago still works.
> 
> Addresses <https://bugzilla.kernel.org/show_bug.cgi?id=43641>.
> 
> Reported-bisected-and-tested-by: Octavio Alvarez <alvarezp@...arezp.com>
> Reported-by: Adrian Knoth <adi@...omp.erfurt.thur.de>
> Signed-off-by: Jonathan Nieder <jrnieder@...il.com>
> Cc: <stable@...r.kernel.org> # 3.4
> ---
> Rafael J. Wysocki wrote:
> 
> > Can you please repost it with _both_ the changelog and the patch?
> 
> Here you go.  Sorry about that.

Thanks!

Applied to the linux-next branch of the linux-pm.git tree.

I think I'll push it for v3.6, since the bug is serious and is a regression.

Bob, I think we should incorporate this into ACPICA, shouldn't we?

Rafael


>  drivers/acpi/acpica/hwsleep.c |   22 ----------------------
>  1 file changed, 22 deletions(-)
> 
> diff --git a/drivers/acpi/acpica/hwsleep.c b/drivers/acpi/acpica/hwsleep.c
> index 0ed85cac3231..615996a36bed 100644
> --- a/drivers/acpi/acpica/hwsleep.c
> +++ b/drivers/acpi/acpica/hwsleep.c
> @@ -95,18 +95,6 @@ acpi_status acpi_hw_legacy_sleep(u8 sleep_state, u8 flags)
>  		return_ACPI_STATUS(status);
>  	}
>  
> -	if (sleep_state != ACPI_STATE_S5) {
> -		/*
> -		 * Disable BM arbitration. This feature is contained within an
> -		 * optional register (PM2 Control), so ignore a BAD_ADDRESS
> -		 * exception.
> -		 */
> -		status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
> -		if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
> -			return_ACPI_STATUS(status);
> -		}
> -	}
> -
>  	/*
>  	 * 1) Disable/Clear all GPEs
>  	 * 2) Enable all wakeup GPEs
> @@ -364,16 +352,6 @@ acpi_status acpi_hw_legacy_wake(u8 sleep_state, u8 flags)
>  				    [ACPI_EVENT_POWER_BUTTON].
>  				    status_register_id, ACPI_CLEAR_STATUS);
>  
> -	/*
> -	 * Enable BM arbitration. This feature is contained within an
> -	 * optional register (PM2 Control), so ignore a BAD_ADDRESS
> -	 * exception.
> -	 */
> -	status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
> -	if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
> -		return_ACPI_STATUS(status);
> -	}
> -
>  	acpi_hw_execute_sleep_method(METHOD_PATHNAME__SST, ACPI_SST_WORKING);
>  	return_ACPI_STATUS(status);
>  }
> 

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