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@xxxxxxx>
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;
--
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