linux-kernel - RE: [PATCH 3/3] ACPI / scan: Enable GPEs before scanning the namespace

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Message-ID: <1AE640813FDE7649BE1B193DEA596E886CF0AFE3@SHSMSX101.ccr.corp.intel.com>
Date:   Tue, 15 Aug 2017 02:12:24 +0000
From:   "Zheng, Lv" <lv.zheng@...el.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux ACPI <linux-acpi@...r.kernel.org>
CC:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Linux PCI <linux-pci@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Moore, Robert" <robert.moore@...el.com>
Subject: RE: [PATCH 3/3] ACPI / scan: Enable GPEs before scanning the
 namespace

Hi, Rafael

> From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-owner@...r.kernel.org] On Behalf Of Rafael J.
> Wysocki
> Subject: [PATCH 3/3] ACPI / scan: Enable GPEs before scanning the namespace
> 
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> On some systems the platform firmware expects GPEs to be enabled
> before the enumeration of devices and if that expectation is not
> met, the systems in question may not boot in some situations.
> 
> For this reason, change the initialization ordering of the ACPI
> subsystem to make it enable GPEs before scanning the namespace
> for the first time in order to enumerate devices.
> 
> Reported-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Suggested-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/scan.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -2139,6 +2139,10 @@ int __init acpi_scan_init(void)
>  			acpi_get_spcr_uart_addr();
>  	}
> 
> +	acpi_gpe_apply_masked_gpes();
> +	acpi_update_all_gpes();
> +	acpi_ec_ecdt_start();
> +

Just for your information.
A recent internal bug reveals that acpi_ec_ecdt_start() should only be
invoked after the enumeration (acpi_ec_add()) for now.
The function contains logics that need to be altered by acpi_ec_add().

So it seems we can only do less aggressive change by moving the GPE
related 2 lines up.

Thanks and best regards
Lv

>  	mutex_lock(&acpi_scan_lock);
>  	/*
>  	 * Enumerate devices in the ACPI namespace.
> @@ -2163,10 +2167,6 @@ int __init acpi_scan_init(void)
>  		}
>  	}
> 
> -	acpi_gpe_apply_masked_gpes();
> -	acpi_update_all_gpes();
> -	acpi_ec_ecdt_start();
> -
>  	acpi_scan_initialized = true;
> 
>   out:
> 
> 
> --
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