[PATCH] PNPACPI: Register disabled resources

[PATCH] PNPACPI: Register disabled resources

[Witold Szczeponik]

When parsing PnP resources, it may happen that some of these
are disabled.  The current solution is to skip these resources
completely - with the unfortunate side effect that they are not
registered despite the fact that they exist, after all.  The
downside of his is that these resources cannot be manipulated
programatically.  The kernel's APM implementation does not suffer
from this problem.

This patch fixes a problem with (at least) some vintage IBM
ThinkPad 600E (and most likely also on the 600, 600X, and 770X
which have a very similar layout) where some of its PnP devices
support options where either an IRQ or DMA is disabled.  The
manipulation of these resources is important because the 600E
has very special requirements.

The patch applies the idea to register disabled resources to
all types of resources, not just to IRQs and DMAs.

No regressions were observed on hardware that does not require
this patch.

The patch is applied against 2.6.39.


Signed-off-by: Witold Szczeponik <Witold.Szczeponik@gmx.net>


Index: linux/drivers/pnp/pnpacpi/rsparser.c
===================================================================
--- linux.orig/drivers/pnp/pnpacpi/rsparser.c
+++ linux/drivers/pnp/pnpacpi/rsparser.c
@@ -509,15 +509,15 @@ static __init void pnpacpi_parse_dma_opt
  					    struct acpi_resource_dma *p)
  {
  	int i;
-	unsigned char map = 0, flags;
+	unsigned char map = 0, flags = 0;

  	if (p->channel_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	for (i = 0; i < p->channel_count; i++)
  		map |= 1 << p->channels[i];

-	flags = dma_flags(dev, p->type, p->bus_master, p->transfer);
+	flags |= dma_flags(dev, p->type, p->bus_master, p->transfer);
  	pnp_register_dma_resource(dev, option_flags, map, flags);
  }

@@ -527,17 +527,17 @@ static __init void pnpacpi_parse_irq_opt
  {
  	int i;
  	pnp_irq_mask_t map;
-	unsigned char flags;
+	unsigned char flags = 0;

  	if (p->interrupt_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	bitmap_zero(map.bits, PNP_IRQ_NR);
  	for (i = 0; i < p->interrupt_count; i++)
  		if (p->interrupts[i])
  			__set_bit(p->interrupts[i], map.bits);

-	flags = irq_flags(p->triggering, p->polarity, p->sharable);
+	flags |= irq_flags(p->triggering, p->polarity, p->sharable);
  	pnp_register_irq_resource(dev, option_flags, &map, flags);
  }

@@ -547,10 +547,10 @@ static __init void pnpacpi_parse_ext_irq
  {
  	int i;
  	pnp_irq_mask_t map;
-	unsigned char flags;
+	unsigned char flags = 0;

  	if (p->interrupt_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	bitmap_zero(map.bits, PNP_IRQ_NR);
  	for (i = 0; i < p->interrupt_count; i++) {
@@ -564,7 +564,7 @@ static __init void pnpacpi_parse_ext_irq
  		}
  	}

-	flags = irq_flags(p->triggering, p->polarity, p->sharable);
+	flags |= irq_flags(p->triggering, p->polarity, p->sharable);
  	pnp_register_irq_resource(dev, option_flags, &map, flags);
  }

@@ -575,10 +575,10 @@ static __init void pnpacpi_parse_port_op
  	unsigned char flags = 0;

  	if (io->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	if (io->io_decode == ACPI_DECODE_16)
-		flags = IORESOURCE_IO_16BIT_ADDR;
+		flags |= IORESOURCE_IO_16BIT_ADDR;
  	pnp_register_port_resource(dev, option_flags, io->minimum, io->maximum,
  				   io->alignment, io->address_length, flags);
  }
@@ -587,11 +587,13 @@ static __init void pnpacpi_parse_fixed_p
  					unsigned int option_flags,
  					struct acpi_resource_fixed_io *io)
  {
+	unsigned char flags = 0;
+
  	if (io->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	pnp_register_port_resource(dev, option_flags, io->address, io->address,
-				   0, io->address_length, IORESOURCE_IO_FIXED);
+				   0, io->address_length, flags | IORESOURCE_IO_FIXED);
  }

  static __init void pnpacpi_parse_mem24_option(struct pnp_dev *dev,
@@ -601,10 +603,10 @@ static __init void pnpacpi_parse_mem24_o
  	unsigned char flags = 0;

  	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
  	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
  				  p->alignment, p->address_length, flags);
  }
@@ -616,10 +618,10 @@ static __init void pnpacpi_parse_mem32_o
  	unsigned char flags = 0;

  	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
  	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
  				  p->alignment, p->address_length, flags);
  }
@@ -631,10 +633,10 @@ static __init void pnpacpi_parse_fixed_m
  	unsigned char flags = 0;

  	if (p->address_length == 0)
-		return;
+		iflags |= IORESOURCE_DISABLED;

  	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
  	pnp_register_mem_resource(dev, option_flags, p->address, p->address,
  				  0, p->address_length, flags);
  }
@@ -655,18 +657,18 @@ static __init void pnpacpi_parse_address
  	}

  	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	if (p->resource_type == ACPI_MEMORY_RANGE) {
  		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
-			flags = IORESOURCE_MEM_WRITEABLE;
+			flags |= IORESOURCE_MEM_WRITEABLE;
  		pnp_register_mem_resource(dev, option_flags, p->minimum,
  					  p->minimum, 0, p->address_length,
  					  flags);
  	} else if (p->resource_type == ACPI_IO_RANGE)
  		pnp_register_port_resource(dev, option_flags, p->minimum,
  					   p->minimum, 0, p->address_length,
-					   IORESOURCE_IO_FIXED);
+					   flags | IORESOURCE_IO_FIXED);
  }

  static __init void pnpacpi_parse_ext_address_option(struct pnp_dev *dev,
@@ -677,18 +679,18 @@ static __init void pnpacpi_parse_ext_add
  	unsigned char flags = 0;

  	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;

  	if (p->resource_type == ACPI_MEMORY_RANGE) {
  		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
-			flags = IORESOURCE_MEM_WRITEABLE;
+			flags |= IORESOURCE_MEM_WRITEABLE;
  		pnp_register_mem_resource(dev, option_flags, p->minimum,
  					  p->minimum, 0, p->address_length,
  					  flags);
  	} else if (p->resource_type == ACPI_IO_RANGE)
  		pnp_register_port_resource(dev, option_flags, p->minimum,
  					   p->minimum, 0, p->address_length,
-					   IORESOURCE_IO_FIXED);
+					   flags | IORESOURCE_IO_FIXED);
  }

  struct acpipnp_parse_option_s {

Re: [PATCH] PNPACPI: Register disabled resources

[Henrique de Moraes Holschuh]

On Fri, 24 Jun 2011, Witold Szczeponik wrote:
> When parsing PnP resources, it may happen that some of these
> are disabled.  The current solution is to skip these resources
> completely - with the unfortunate side effect that they are not
> registered despite the fact that they exist, after all.  The
> downside of his is that these resources cannot be manipulated
> programatically.  The kernel's APM implementation does not suffer
> from this problem.
> 
> This patch fixes a problem with (at least) some vintage IBM
> ThinkPad 600E (and most likely also on the 600, 600X, and 770X
> which have a very similar layout) where some of its PnP devices
> support options where either an IRQ or DMA is disabled.  The
> manipulation of these resources is important because the 600E
> has very special requirements.
> 
> The patch applies the idea to register disabled resources to
> all types of resources, not just to IRQs and DMAs.

Maybe you could post to the linux-thinkpad ML a follow up, mentioning this
patch and how these thinkpad users should use it plus whatever userspace to
improve the suport for their boxes?

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] PNPACPI: Register disabled resources

[Witold Szczeponik]

Am 25.06.2011 04:54, schrieb Henrique de Moraes Holschuh:

>
> Maybe you could post to the linux-thinkpad ML a follow up, mentioning this
> patch and how these thinkpad users should use it plus whatever userspace to
> improve the suport for their boxes?
>

Hi Henrique,

I will send out a more detailed patch description shortly.  Since a 
subtle typo sneaked into the original patch, resending the entire patch 
makes sense (to me).  I will also include the linux-thinkpad ML.

--- Witold

[PATCH v2] PNPACPI: Register disabled resources

[Witold Szczeponik]

When parsing PnP ACPI resource structures, it may happen that some of the 
resources are disabled (in which case "the size" of the resource equals zero).  
The current solution is to skip these resources completely - with the 
unfortunate side effect that they are not registered despite the fact that 
they exist, after all.  (The downside of this approach is that these resources
cannot be used as templates for setting the actual device's resources 
because they are missing from the template.) The kernel's APM implementation 
does not suffer from this problem and registers all resources regardless of 
"their size".

This patch fixes a problem with (at least) the vintage IBM ThinkPad 600E 
(and most likely also with the 600, 600X, and 770X which have a very 
similar layout) where some of its PnP devices support options where either 
an IRQ, a DMA, or an IO port is disabled.  Without this patch, the devices
can not be configured using the "/sys/bus/pnp/devices/*/resources" interface. 

The manipulation of these resources is important because the 600E has very 
demanding requirements.  For instance, the number of IRQs is not sufficient 
to support all devices of the 600E.  Fortunately, some of the devices, 
like the sound card's MPU-401 UART, can be configured to not use any IRQ, 
hence freeing an IRQ for a device that requires one.  (Still, the device's 
"ResourceTemplate" requires an IRQ resource descriptor which cannot be 
created if the resource has not been registered in the first place.)  

As an example, the dependent sets of the 600E's CSC0103 device (the MPU-401 
UART) are listed, with the patch applied, as: 

  Dependent: 00 - Priority preferred
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq <none> High-Edge
  Dependent: 01 - Priority acceptable
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq 5,7,2/9,10,11,15 High-Edge

(The same result is obtained when PNPBIOS is used instead of PnP ACPI.) 
Without the patch, the IRQ resource in the preferred option is not listed 
at all: 

  Dependent: 00 - Priority preferred
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
  Dependent: 01 - Priority acceptable
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq 5,7,2/9,10,11,15 High-Edge
	
And in fact, the 600E's DSDT lists the disabled IRQ as an option, as can  be 
seen from the following excerpt from the DSDT:

	Name (_PRS, ResourceTemplate ()
	{
        StartDependentFn (0x00, 0x00)
        {
            IO (Decode16, 0x0300, 0x0330, 0x10, 0x04)
            IRQNoFlags () {}
        }
        StartDependentFn (0x01, 0x00)
        {
            IO (Decode16, 0x0300, 0x0330, 0x10, 0x04)
            IRQNoFlags () {5,7,9,10,11,15}
        }
        EndDependentFn ()
	})

With this patch applied, a user space program - or maybe even the kernel - 
can  allocate all devices' resources optimally.  For the 600E, this means 
to find optimal resources for (at least) the serial port, the parallel port, 
the infrared port, the MWAVE modem, the sound card, and the MPU-401 UART. 

The patch applies the idea to register disabled resources to all types of 
resources, not just to IRQs, DMAs, and IO ports.  At the same time, it mimics 
the behavior of the "pnp_assign_xxx" functions from "drivers/pnp/manager.c" 
where resources with "no size" are considered disabled. 

No regressions were observed on hardware that does not require this patch. 

The patch is applied against 2.6.39.

NB: The kernel's current PnP interface does not allow for disabling individual
resources using the "/sys/bus/pnp/devices/$device/resources" file.  Assuming 
this could be done, a device could be configured to use a disabled resource 
using a simple series of calls: 

  echo disable > /sys/bus/pnp/devices/$device/resources
  echo clear > /sys/bus/pnp/devices/$device/resources
  echo set irq disabled > /sys/bus/pnp/devices/$device/resources
  echo fill > /sys/bus/pnp/devices/$device/resources
  echo activate > /sys/bus/pnp/devices/$device/resources

This patch addresses only the parsing of PnP ACPI devices.  


ChangeLog (v1 -> v2):
 - extend patch description
 - fix typo in patch itself


Signed-off-by: Witold Szczeponik <Witold.Szczeponik@gmx.net>


Index: linux/drivers/pnp/pnpacpi/rsparser.c
===================================================================
--- linux.orig/drivers/pnp/pnpacpi/rsparser.c
+++ linux/drivers/pnp/pnpacpi/rsparser.c
@@ -509,15 +509,15 @@ static __init void pnpacpi_parse_dma_opt
 					    struct acpi_resource_dma *p)
 {
 	int i;
-	unsigned char map = 0, flags;
+	unsigned char map = 0, flags = 0;
 
 	if (p->channel_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	for (i = 0; i < p->channel_count; i++)
 		map |= 1 << p->channels[i];
 
-	flags = dma_flags(dev, p->type, p->bus_master, p->transfer);
+	flags |= dma_flags(dev, p->type, p->bus_master, p->transfer);
 	pnp_register_dma_resource(dev, option_flags, map, flags);
 }
 
@@ -527,17 +527,17 @@ static __init void pnpacpi_parse_irq_opt
 {
 	int i;
 	pnp_irq_mask_t map;
-	unsigned char flags;
+	unsigned char flags = 0;
 
 	if (p->interrupt_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	bitmap_zero(map.bits, PNP_IRQ_NR);
 	for (i = 0; i < p->interrupt_count; i++)
 		if (p->interrupts[i])
 			__set_bit(p->interrupts[i], map.bits);
 
-	flags = irq_flags(p->triggering, p->polarity, p->sharable);
+	flags |= irq_flags(p->triggering, p->polarity, p->sharable);
 	pnp_register_irq_resource(dev, option_flags, &map, flags);
 }
 
@@ -547,10 +547,10 @@ static __init void pnpacpi_parse_ext_irq
 {
 	int i;
 	pnp_irq_mask_t map;
-	unsigned char flags;
+	unsigned char flags = 0;
 
 	if (p->interrupt_count == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	bitmap_zero(map.bits, PNP_IRQ_NR);
 	for (i = 0; i < p->interrupt_count; i++) {
@@ -564,7 +564,7 @@ static __init void pnpacpi_parse_ext_irq
 		}
 	}
 
-	flags = irq_flags(p->triggering, p->polarity, p->sharable);
+	flags |= irq_flags(p->triggering, p->polarity, p->sharable);
 	pnp_register_irq_resource(dev, option_flags, &map, flags);
 }
 
@@ -575,10 +575,10 @@ static __init void pnpacpi_parse_port_op
 	unsigned char flags = 0;
 
 	if (io->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (io->io_decode == ACPI_DECODE_16)
-		flags = IORESOURCE_IO_16BIT_ADDR;
+		flags |= IORESOURCE_IO_16BIT_ADDR;
 	pnp_register_port_resource(dev, option_flags, io->minimum, io->maximum,
 				   io->alignment, io->address_length, flags);
 }
@@ -587,11 +587,13 @@ static __init void pnpacpi_parse_fixed_p
 					unsigned int option_flags,
 					struct acpi_resource_fixed_io *io)
 {
+	unsigned char flags = 0;
+
 	if (io->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	pnp_register_port_resource(dev, option_flags, io->address, io->address,
-				   0, io->address_length, IORESOURCE_IO_FIXED);
+				   0, io->address_length, flags | IORESOURCE_IO_FIXED);
 }
 
 static __init void pnpacpi_parse_mem24_option(struct pnp_dev *dev,
@@ -601,10 +603,10 @@ static __init void pnpacpi_parse_mem24_o
 	unsigned char flags = 0;
 
 	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
 				  p->alignment, p->address_length, flags);
 }
@@ -616,10 +618,10 @@ static __init void pnpacpi_parse_mem32_o
 	unsigned char flags = 0;
 
 	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
 				  p->alignment, p->address_length, flags);
 }
@@ -631,10 +633,10 @@ static __init void pnpacpi_parse_fixed_m
 	unsigned char flags = 0;
 
 	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
-		flags = IORESOURCE_MEM_WRITEABLE;
+		flags |= IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->address, p->address,
 				  0, p->address_length, flags);
 }
@@ -655,18 +657,18 @@ static __init void pnpacpi_parse_address
 	}
 
 	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (p->resource_type == ACPI_MEMORY_RANGE) {
 		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
-			flags = IORESOURCE_MEM_WRITEABLE;
+			flags |= IORESOURCE_MEM_WRITEABLE;
 		pnp_register_mem_resource(dev, option_flags, p->minimum,
 					  p->minimum, 0, p->address_length,
 					  flags);
 	} else if (p->resource_type == ACPI_IO_RANGE)
 		pnp_register_port_resource(dev, option_flags, p->minimum,
 					   p->minimum, 0, p->address_length,
-					   IORESOURCE_IO_FIXED);
+					   flags | IORESOURCE_IO_FIXED);
 }
 
 static __init void pnpacpi_parse_ext_address_option(struct pnp_dev *dev,
@@ -677,18 +679,18 @@ static __init void pnpacpi_parse_ext_add
 	unsigned char flags = 0;
 
 	if (p->address_length == 0)
-		return;
+		flags |= IORESOURCE_DISABLED;
 
 	if (p->resource_type == ACPI_MEMORY_RANGE) {
 		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
-			flags = IORESOURCE_MEM_WRITEABLE;
+			flags |= IORESOURCE_MEM_WRITEABLE;
 		pnp_register_mem_resource(dev, option_flags, p->minimum,
 					  p->minimum, 0, p->address_length,
 					  flags);
 	} else if (p->resource_type == ACPI_IO_RANGE)
 		pnp_register_port_resource(dev, option_flags, p->minimum,
 					   p->minimum, 0, p->address_length,
-					   IORESOURCE_IO_FIXED);
+					   flags | IORESOURCE_IO_FIXED);
 }
 
 struct acpipnp_parse_option_s {

Re: [PATCH v2] PNPACPI: Register disabled resources

[Henrique de Moraes Holschuh]

Thank you for the extended description.  Unfortunately, I don't know
enough about the PNPBIPS/PNPACPI subsystem to comment further on the
patch, but it does look useful.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

[PATCH v3] PNPACPI: Register disabled/empty resources

[Witold Szczeponik]

When parsing PnP ACPI resource structures, it may happen that some of the 
resources are "empty" (in which case "the size" of the resource equals zero).  
The current solution is to skip these resources completely - with the 
unfortunate side effect that they are not registered despite the fact that 
they exist, after all.  (The downside of this approach is that these resources
cannot be used as templates for setting the actual device's resources 
because they are missing from the template.) The kernel's PNPBIOS implementation 
does not suffer from this problem and registers all resources regardless of 
their "size".

This patch fixes a problem with (at least) the vintage IBM ThinkPad 600E (and 
most likely also with the 600, 600X, and 770X which have a very similar layout) 
where some of its PnP devices support options where either an IRQ, a DMA, or an 
IO port is disabled.  Without this patch, the devices can not be configured 
using the "/sys/bus/pnp/devices/*/resources" interface. 

The manipulation of these resources is important because the 600E has very 
demanding requirements.  For instance, the number of IRQs is not sufficient to 
support all devices of the 600E.  Fortunately, some of the devices, like the 
sound card's MPU-401 UART, can be configured to not use any IRQ, hence freeing 
an IRQ for a device that requires one.  (Still, the device's "ResourceTemplate" 
requires an IRQ resource descriptor which cannot be created if the resource has 
not been registered in the first place.)  

As an example, the dependent sets of the 600E's CSC0103 device (the MPU-401 
UART) are listed, with the patch applied, as: 

  Dependent: 00 - Priority preferred
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq <none> High-Edge
  Dependent: 01 - Priority acceptable
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq 5,7,2/9,10,11,15 High-Edge

(The same result is obtained when PNPBIOS is used instead of PNPACPI.) Without 
the patch, the IRQ resource in the preferred option is not listed at all: 

  Dependent: 00 - Priority preferred
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
  Dependent: 01 - Priority acceptable
    port 0x300-0x330, align 0xf, size 0x4, 16-bit address decoding
    irq 5,7,2/9,10,11,15 High-Edge
	
And in fact, the 600E's DSDT lists the empty IRQ as an option, as can  be seen 
from the following excerpt from the DSDT:

    Name (_PRS, ResourceTemplate ()
    {
        StartDependentFn (0x00, 0x00)
        {
            IO (Decode16, 0x0300, 0x0330, 0x10, 0x04)
            IRQNoFlags () {}
        }
        StartDependentFn (0x01, 0x00)
        {
            IO (Decode16, 0x0300, 0x0330, 0x10, 0x04)
            IRQNoFlags () {5,7,9,10,11,15}
        }
        EndDependentFn ()
    })

With this patch applied, a user space program - or maybe even the kernel - can 
allocate all devices' resources optimally.  For the 600E, this means to find 
optimal resources for (at least) the serial port, the parallel port, the 
infrared port, the MWAVE modem, the sound card, and the MPU-401 UART. 

The patch applies the idea to register disabled resources to all types of 
resources, not just to IRQs, DMAs, and IO ports. 

No regressions were observed on hardware that does not require this patch. 

The patch is applied against 3.0 (or against the current development tree
with 29df8d8f8702f0f53c1375015f09f04bc8d023c1 reverted).


NB: The kernel's current PnP interface does not allow for disabling individual
resources using the "/sys/bus/pnp/devices/$device/resources" file.  Assuming 
this could be done, a device could be configured to use a disabled resource 
using a simple series of calls: 

  echo disable > /sys/bus/pnp/devices/$device/resources
  echo clear > /sys/bus/pnp/devices/$device/resources
  echo set irq disabled > /sys/bus/pnp/devices/$device/resources
  echo fill > /sys/bus/pnp/devices/$device/resources
  echo activate > /sys/bus/pnp/devices/$device/resources

This patch addresses only the parsing of PNPACPI devices.  


ChangeLog (v2 -> v3):
 - change patch description
 - remove marking resources as disabled

ChangeLog (v1 -> v2):
 - extend patch description
 - fix typo in patch itself


Signed-off-by: Witold Szczeponik <Witold.Szczeponik@gmx.net>


Index: linux/drivers/pnp/pnpacpi/rsparser.c
===================================================================
--- linux.orig/drivers/pnp/pnpacpi/rsparser.c
+++ linux/drivers/pnp/pnpacpi/rsparser.c
@@ -511,9 +511,6 @@ static __init void pnpacpi_parse_dma_opt
 	int i;
 	unsigned char map = 0, flags;
 
-	if (p->channel_count == 0)
-		return;
-
 	for (i = 0; i < p->channel_count; i++)
 		map |= 1 << p->channels[i];
 
@@ -529,9 +526,6 @@ static __init void pnpacpi_parse_irq_opt
 	pnp_irq_mask_t map;
 	unsigned char flags;
 
-	if (p->interrupt_count == 0)
-		return;
-
 	bitmap_zero(map.bits, PNP_IRQ_NR);
 	for (i = 0; i < p->interrupt_count; i++)
 		if (p->interrupts[i])
@@ -549,9 +543,6 @@ static __init void pnpacpi_parse_ext_irq
 	pnp_irq_mask_t map;
 	unsigned char flags;
 
-	if (p->interrupt_count == 0)
-		return;
-
 	bitmap_zero(map.bits, PNP_IRQ_NR);
 	for (i = 0; i < p->interrupt_count; i++) {
 		if (p->interrupts[i]) {
@@ -574,9 +565,6 @@ static __init void pnpacpi_parse_port_op
 {
 	unsigned char flags = 0;
 
-	if (io->address_length == 0)
-		return;
-
 	if (io->io_decode == ACPI_DECODE_16)
 		flags = IORESOURCE_IO_16BIT_ADDR;
 	pnp_register_port_resource(dev, option_flags, io->minimum, io->maximum,
@@ -587,9 +575,6 @@ static __init void pnpacpi_parse_fixed_p
 					unsigned int option_flags,
 					struct acpi_resource_fixed_io *io)
 {
-	if (io->address_length == 0)
-		return;
-
 	pnp_register_port_resource(dev, option_flags, io->address, io->address,
 				   0, io->address_length, IORESOURCE_IO_FIXED);
 }
@@ -600,9 +585,6 @@ static __init void pnpacpi_parse_mem24_o
 {
 	unsigned char flags = 0;
 
-	if (p->address_length == 0)
-		return;
-
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
 		flags = IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
@@ -615,9 +597,6 @@ static __init void pnpacpi_parse_mem32_o
 {
 	unsigned char flags = 0;
 
-	if (p->address_length == 0)
-		return;
-
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
 		flags = IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->minimum, p->maximum,
@@ -630,9 +609,6 @@ static __init void pnpacpi_parse_fixed_m
 {
 	unsigned char flags = 0;
 
-	if (p->address_length == 0)
-		return;
-
 	if (p->write_protect == ACPI_READ_WRITE_MEMORY)
 		flags = IORESOURCE_MEM_WRITEABLE;
 	pnp_register_mem_resource(dev, option_flags, p->address, p->address,
@@ -654,9 +630,6 @@ static __init void pnpacpi_parse_address
 		return;
 	}
 
-	if (p->address_length == 0)
-		return;
-
 	if (p->resource_type == ACPI_MEMORY_RANGE) {
 		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
 			flags = IORESOURCE_MEM_WRITEABLE;
@@ -676,9 +649,6 @@ static __init void pnpacpi_parse_ext_add
 	struct acpi_resource_extended_address64 *p = &r->data.ext_address64;
 	unsigned char flags = 0;
 
-	if (p->address_length == 0)
-		return;
-
 	if (p->resource_type == ACPI_MEMORY_RANGE) {
 		if (p->info.mem.write_protect == ACPI_READ_WRITE_MEMORY)
 			flags = IORESOURCE_MEM_WRITEABLE;