From 2846d84ffa4408c9810fabad74cb7aec410352fc Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 24 May 2011 12:11:48 +0100 Subject: [PATCH] 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 Signed-off-by: Russell King --- arch/arm/include/asm/fiq.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm/include/asm/fiq.h b/arch/arm/include/asm/fiq.h index 45bb3eeeab7c..d493d0b742a1 100644 --- a/arch/arm/include/asm/fiq.h +++ b/arch/arm/include/asm/fiq.h @@ -4,6 +4,13 @@ * Support for FIQ on ARM architectures. * Written by Philip Blundell , 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 -- 2.20.1