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PNP: support optional IRQ resources
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This patch adds an IORESOURCE_IRQ_OPTIONAL flag for use when
assigning resources to a device.  If the flag is set and we are
unable to assign an IRQ to the device, we can leave the IRQ
disabled but allow the overall resource allocation to succeed.

Some devices request an IRQ, but can run without an IRQ
(possibly with degraded performance).  This flag lets us run
the device without the IRQ instead of just leaving the
device disabled.

This is a reimplementation of this previous change by Rene
Herman <[email protected]>:
    http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3b73a223661ed137c5d3d2635f954382e94f5a43

I reimplemented this for two reasons:
    - to prepare for converting all resource options into a single linked
      list, as opposed to the per-resource-type lists we have now, and
    - to preserve the order and number of resource options.

In PNPBIOS and ACPI, we configure a device by giving firmware a
list of resource assignments.  It is important that this list
has exactly the same number of resources, in the same order,
as the "template" list we got from the firmware in the first
place.

The problem of a sound card MPU401 being left disabled for want of
an IRQ was reported by Uwe Bugla <[email protected]>.

Signed-off-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Rene Herman <[email protected]>
Signed-off-by: Len Brown <[email protected]>
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Bjorn Helgaas authored and Andi Kleen committed Jul 16, 2008
1 parent 2d29a7a commit d5ebde6
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Showing 4 changed files with 39 additions and 44 deletions.
2 changes: 2 additions & 0 deletions drivers/pnp/interface.c
Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,8 @@ static void pnp_print_irq(pnp_info_buffer_t * buffer, char *space,
pnp_printf(buffer, " High-Level");
if (irq->flags & IORESOURCE_IRQ_LOWLEVEL)
pnp_printf(buffer, " Low-Level");
if (irq->flags & IORESOURCE_IRQ_OPTIONAL)
pnp_printf(buffer, " (optional)");
pnp_printf(buffer, "\n");
}

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9 changes: 9 additions & 0 deletions drivers/pnp/manager.c
Original file line number Diff line number Diff line change
Expand Up @@ -153,6 +153,15 @@ static int pnp_assign_irq(struct pnp_dev *dev, struct pnp_irq *rule, int idx)
goto __add;
}
}

if (rule->flags & IORESOURCE_IRQ_OPTIONAL) {
res->start = -1;
res->end = -1;
res->flags |= IORESOURCE_DISABLED;
dev_dbg(&dev->dev, " irq %d disabled (optional)\n", idx);
goto __add;
}

dev_dbg(&dev->dev, " couldn't assign irq %d\n", idx);
return -EBUSY;

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71 changes: 27 additions & 44 deletions drivers/pnp/quirks.c
Original file line number Diff line number Diff line change
Expand Up @@ -121,34 +121,46 @@ static struct pnp_option *quirk_isapnp_mpu_options(struct pnp_dev *dev)
struct pnp_option *res;

/*
* Build a functional IRQ-less variant of each MPU option.
* Build a functional IRQ-optional variant of each MPU option.
*/

for (res = dev->dependent; res; res = res->next) {
struct pnp_option *curr;
struct pnp_port *port;
struct pnp_port *copy;
struct pnp_port *copy_port;
struct pnp_irq *irq;
struct pnp_irq *copy_irq;

port = res->port;
if (!port || !res->irq)
irq = res->irq;
if (!port || !irq)
continue;

copy = pnp_alloc(sizeof *copy);
if (!copy)
copy_port = pnp_alloc(sizeof *copy_port);
if (!copy_port)
break;

copy_irq = pnp_alloc(sizeof *copy_irq);
if (!copy_irq) {
kfree(copy_port);
break;
}

*copy_port = *port;
copy_port->next = NULL;

copy->min = port->min;
copy->max = port->max;
copy->align = port->align;
copy->size = port->size;
copy->flags = port->flags;
*copy_irq = *irq;
copy_irq->flags |= IORESOURCE_IRQ_OPTIONAL;
copy_irq->next = NULL;

curr = pnp_build_option(PNP_RES_PRIORITY_FUNCTIONAL);
if (!curr) {
kfree(copy);
kfree(copy_port);
kfree(copy_irq);
break;
}
curr->port = copy;
curr->port = copy_port;
curr->irq = copy_irq;

if (prev)
prev->next = curr;
Expand All @@ -157,7 +169,7 @@ static struct pnp_option *quirk_isapnp_mpu_options(struct pnp_dev *dev)
prev = curr;
}
if (head)
dev_info(&dev->dev, "adding IRQ-less MPU options\n");
dev_info(&dev->dev, "adding IRQ-optional MPU options\n");

return head;
}
Expand All @@ -167,10 +179,6 @@ static void quirk_ad1815_mpu_resources(struct pnp_dev *dev)
struct pnp_option *res;
struct pnp_irq *irq;

/*
* Distribute the independent IRQ over the dependent options
*/

res = dev->independent;
if (!res)
return;
Expand All @@ -179,33 +187,8 @@ static void quirk_ad1815_mpu_resources(struct pnp_dev *dev)
if (!irq || irq->next)
return;

res = dev->dependent;
if (!res)
return;

while (1) {
struct pnp_irq *copy;

copy = pnp_alloc(sizeof *copy);
if (!copy)
break;

bitmap_copy(copy->map.bits, irq->map.bits, PNP_IRQ_NR);
copy->flags = irq->flags;

copy->next = res->irq; /* Yes, this is NULL */
res->irq = copy;

if (!res->next)
break;
res = res->next;
}
kfree(irq);

res->next = quirk_isapnp_mpu_options(dev);

res = dev->independent;
res->irq = NULL;
irq->flags |= IORESOURCE_IRQ_OPTIONAL;
dev_info(&dev->dev, "made independent IRQ optional\n");
}

static void quirk_isapnp_mpu_resources(struct pnp_dev *dev)
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1 change: 1 addition & 0 deletions include/linux/ioport.h
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ struct resource_list {
#define IORESOURCE_IRQ_HIGHLEVEL (1<<2)
#define IORESOURCE_IRQ_LOWLEVEL (1<<3)
#define IORESOURCE_IRQ_SHAREABLE (1<<4)
#define IORESOURCE_IRQ_OPTIONAL (1<<5)

/* PnP DMA specific bits (IORESOURCE_BITS) */
#define IORESOURCE_DMA_TYPE_MASK (3<<0)
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