Commit 2846d84f authored May 24, 2011 by Dave Martin Committed by Russell King May 26, 2011

ARM: 6940/1: fiq: Briefly document driver responsibilities for suspend/resume



Drivers which make use of the FIQ interrupt may require the state
of the FIQ mode registers to be preserved across suspend/resume.

Because the FIQ mode registers are not saved and restored
automatically by the kernel, driver authors will need to do the
appropriate save/restore in their own driver suspend/resume
handlers.

Implementing global automatic save/restore of the FIQ state does
not appear appropriate, since this by itself is not sufficient for
FIQ-based drivers to function correctly across suspend/resume in
any case.

This patch adds a brief explanatory note to fiq.h documenting the
requirement placed on driver authors.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent dc2eb928

arch/arm/include/asm/fiq.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -4,6 +4,13 @@
		* Support for FIQ on ARM architectures.
		* Written by Philip Blundell <philb@gnu.org>, 1998
		* Re-written by Russell King
		*
		* NOTE: The FIQ mode registers are not magically preserved across
		* suspend/resume.
		*
		* Drivers which require these registers to be preserved across power
		* management operations must implement appropriate suspend/resume handlers to
		* save and restore them.
		*/

		#ifndef __ASM_FIQ_H