David Flater bdf0eb3a02 pnp: restore automatic resolution of DMA conflicts ... To fix a 5-year-old regression, reverse changes made by commit 7ef3639 (PNP: don't fail device init if no DMA channel available). As an example to show the problem, my sound card provides a prioritized list of PnP "dependent sets" of requested resources: dependent set 0 (preferred) wants DMA 5. dependent set 1 (acceptable) will take DMA 5, 6, or 7. ... dependent set 4 (acceptable) doesn't request a high DMA. If DMA 5 is not available, pnp_assign_dma has to fail on set 0 so that pnp_auto_config_dev will move on to set 1 and get DMA 6 or 7. Instead, pnp_assign_dma adds the resource with flags |= IORESOURCE_DISABLED and returns success. pnp_auto_config_dev just sees success and therefore chooses set 0 with a disabled DMA and never tries the sets that would have resolved the conflict. Furthermore, this mode of "success" is unexpected and unhandled in sound/isa/sb and probably other drivers. sb assumes that the returned DMA is enabled and obliviously uses the invalid DMA number. Observed consequences were sb successfully grabbing a DMA that was expressly forbidden by the kernel parameter pnp_reserve_dma. The only upside to the original change would be as a kludge for devices that can operate in degraded mode without a DMA but that don't provide the corresponding non-preferred dependent set. The right workaround for those devices is to synthesize the missing set in quirks.c; otherwise, you're reinventing PnP fallback functionality at the driver level for that device and all others. Signed-off-by: David Flater <dave@flaterco.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>		2013-05-22 00:21:02 +02:00
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isapnp	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-05-01 17:51:54 -07:00
pnpacpi	ACPI: Set length even for TYPE_END_TAG acpi resource	2013-03-24 01:00:38 +01:00
pnpbios	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc	2013-05-02 10:16:16 -07:00
base.h	ACPI: Move device resources interpretation code from PNP to ACPI core	2012-11-15 00:30:01 +01:00
card.c	Fix common misspellings	2011-03-31 11:26:23 -03:00
core.c	Merge branch 'pnp' into release	2011-01-12 04:59:44 -05:00
driver.c	PNP / ACPI: Use DEVICE_ACPI_HANDLE() for device ACPI handle access	2011-01-11 15:20:40 -05:00
interface.c	PNP: Simplify setting of resources	2013-01-03 13:10:52 +01:00
Kconfig	PNP: remove old CONFIG_PNP_DEBUG option	2008-10-10 23:35:33 -04:00
Makefile	PNP: Compile all pnp built-in stuff in one module namespace	2010-10-27 02:23:44 -04:00
manager.c	pnp: restore automatic resolution of DMA conflicts	2013-05-22 00:21:02 +02:00
quirks.c	PNP: work around Dell 1536/1546 BIOS MMCONFIG bug that breaks USB	2012-01-06 12:11:20 -08:00
resource.c	ACPI: Move device resources interpretation code from PNP to ACPI core	2012-11-15 00:30:01 +01:00
support.c	PNPACPI: add bus number support	2010-03-14 20:08:38 -04:00
system.c	vsprintf: use %pR, %pr instead of %pRt, %pRf	2009-11-04 13:06:41 -08:00