From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Ondrej Zary <linux@rainbow-software.org>, Matthew Garrett <mjg@redhat.com>
Cc: Len Brown <len.brown@intel.com>, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, Matthew Garrett <mjg59@srcf.ucam.org>
Subject: Re: [bisected] PS/2 keyboard and mouse dead on resume on Intel D845BG
Date: Sun, 07 Oct 2012 21:59:44 +0200
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On Sunday 07 of October 2012 21:00:09 Ondrej Zary wrote:
> On Sunday 07 October 2012 15:13:27 Ondrej Zary wrote:
> > Hello,
> > Intel D845BG board comes out of S3 with PS/2 keyboard and mouse completely
> > dead. The machine works otherwise (with USB keyboard or over network). When
> > rebooted in this state, the BIOS hangs with blank screen. I have the latest
> > BIOS installed (P08).
> >
> > Old kernels worked. Bisection pointed to commit:
> > b6dacf63e9fb2e7a1369843d6cef332f76fca6a3
> > (ACPI: Unconditionally set SCI_EN on resume)
> >
> > Commenting out this line in drivers/acpi/sleep.c:
> > 	acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
> > fixes the problem.
> >
> > Any ideas why this breaks on this system?
> 
> Added acpi_read_bit_register there and it seems that SCI_EN is already set!
> 
> This patch fixes the problem here. I wonder how this affects systems that
> require SCI_EN to be set.

I'm not sure if reading SCI_EN is actually safe on all systems.

Matthew, what do you think?

Rafael


> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -271,6 +271,7 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
>  	acpi_status status = AE_OK;
>  	u32 acpi_state = acpi_target_sleep_state;
>  	int error;
> +	u32 sci_enabled;
>  
>  	ACPI_FLUSH_CPU_CACHE();
>  
> @@ -289,7 +290,9 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
>  	}
>  
>  	/* This violates the spec but is required for bug compatibility. */
> -	acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
> +	acpi_read_bit_register(ACPI_BITREG_SCI_ENABLE, &sci_enabled);
> +	if (!sci_enabled)
> +		acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
>  
>  	/* Reprogram control registers */
>  	acpi_leave_sleep_state_prep(acpi_state);
> 
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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