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Subject[PATCH v2] PNPACPI: Register disabled resources
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 {

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