linux-kernel - Re: ACPI resource change triggers loss of serial ports

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Date:	Mon, 07 Jul 2014 14:57:20 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Andy Whitcroft <apw@...onical.com>, Zhang Rui <rui.zhang@...el.com>
Cc:	Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: ACPI resource change triggers loss of serial ports

On Thursday, June 19, 2014 11:41:30 AM Andy Whitcroft wrote:
> The recently merged change (in v3.14-rc6) to ACPI resource detection
> (below) causes all zero length ACPI resources to be elided from the table:
> 
>   commit b355cee88e3b1a193f0e9a81db810f6f83ad728b
>   Author: Zhang Rui <rui.zhang@...el.com>
>   Date:   Thu Feb 27 11:37:15 2014 +0800
> 
>     ACPI / resources: ignore invalid ACPI device resources
> 
> This change has caused a regression in (at least) serial port detection
> for a number of machines (see LP#1313981 [1]).  These seem to represent
> their IO regions (presumably incorrectly) as a zero length region.
> Reverting the above commit restores these serial devices.
> 
> For Zhang's case I wonder if this check could be tightened up to cover
> only the zero base, something like the (untested) patch below.
> 
> -apw
> 
> [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1313981

I'm going to queue up the patch below for 3.16.

Rui, can you please have a look at this and let me know if there's
anything wrong with it?

Rafael


> From e5211c68278387ef65e483bcfedd5581a79ec783 Mon Sep 17 00:00:00 2001
> From: Andy Whitcroft <apw@...onical.com>
> Date: Thu, 19 Jun 2014 11:19:16 +0100
> Subject: [PATCH] ACPI / Resources: only reject zero length resources based at
>  address zero
> 
> The recently merged change (in v3.14-rc6) to ACPI resource detection
> (below) causes all zero length ACPI resources to be elided from the
> table:
> 
>   commit b355cee88e3b1a193f0e9a81db810f6f83ad728b
>   Author: Zhang Rui <rui.zhang@...el.com>
>   Date:   Thu Feb 27 11:37:15 2014 +0800
> 
>     ACPI / resources: ignore invalid ACPI device resources
> 
> This change has caused a regression in (at least) serial port detection
> for a number of machines (see LP#1313981 [1]).  These seem to represent
> their IO regions (presumably incorrectly) as a zero length region.
> Reverting the above commit restores these serial devices.
> 
> Only elide zero length resources which lie at address 0.
> 
> Signed-off-by: Andy Whitcroft <apw@...onical.com>
> ---
>  drivers/acpi/resource.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 0bdacc5..2ba8f02 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -77,7 +77,7 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
>  	switch (ares->type) {
>  	case ACPI_RESOURCE_TYPE_MEMORY24:
>  		memory24 = &ares->data.memory24;
> -		if (!memory24->address_length)
> +		if (!memory24->minimum && !memory24->address_length)
>  			return false;
>  		acpi_dev_get_memresource(res, memory24->minimum,
>  					 memory24->address_length,
> @@ -85,7 +85,7 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
>  		break;
>  	case ACPI_RESOURCE_TYPE_MEMORY32:
>  		memory32 = &ares->data.memory32;
> -		if (!memory32->address_length)
> +		if (!memory32->minimum && !memory32->address_length)
>  			return false;
>  		acpi_dev_get_memresource(res, memory32->minimum,
>  					 memory32->address_length,
> @@ -93,7 +93,7 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
>  		break;
>  	case ACPI_RESOURCE_TYPE_FIXED_MEMORY32:
>  		fixed_memory32 = &ares->data.fixed_memory32;
> -		if (!fixed_memory32->address_length)
> +		if (!fixed_memory32->address && !fixed_memory32->address_length)
>  			return false;
>  		acpi_dev_get_memresource(res, fixed_memory32->address,
>  					 fixed_memory32->address_length,
> @@ -150,7 +150,7 @@ bool acpi_dev_resource_io(struct acpi_resource *ares, struct resource *res)
>  	switch (ares->type) {
>  	case ACPI_RESOURCE_TYPE_IO:
>  		io = &ares->data.io;
> -		if (!io->address_length)
> +		if (!io->minimum && !io->address_length)
>  			return false;
>  		acpi_dev_get_ioresource(res, io->minimum,
>  					io->address_length,
> @@ -158,7 +158,7 @@ bool acpi_dev_resource_io(struct acpi_resource *ares, struct resource *res)
>  		break;
>  	case ACPI_RESOURCE_TYPE_FIXED_IO:
>  		fixed_io = &ares->data.fixed_io;
> -		if (!fixed_io->address_length)
> +		if (!fixed_io->address && !fixed_io->address_length)
>  			return false;
>  		acpi_dev_get_ioresource(res, fixed_io->address,
>  					fixed_io->address_length,
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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