From patchwork Tue May 24 11:11:48 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 1592 Return-Path: Delivered-To: unknown Received: from imap.gmail.com (74.125.159.109) by localhost6.localdomain6 with IMAP4-SSL; 08 Jun 2011 14:53:24 -0000 Delivered-To: patches@linaro.org Received: by 10.52.181.230 with SMTP id dz6cs154833vdc; Tue, 24 May 2011 04:12:01 -0700 (PDT) Received: by 10.216.145.135 with SMTP id p7mr3345961wej.38.1306235520206; Tue, 24 May 2011 04:12:00 -0700 (PDT) Received: from mail-ww0-f50.google.com (mail-ww0-f50.google.com [74.125.82.50]) by mx.google.com with ESMTPS id d15si13053889wen.173.2011.05.24.04.11.58 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 24 May 2011 04:11:59 -0700 (PDT) Received-SPF: neutral (google.com: 74.125.82.50 is neither permitted nor denied by best guess record for domain of dave.martin@linaro.org) client-ip=74.125.82.50; Authentication-Results: mx.google.com; spf=neutral (google.com: 74.125.82.50 is neither permitted nor denied by best guess record for domain of dave.martin@linaro.org) smtp.mail=dave.martin@linaro.org Received: by wwc33 with SMTP id 33so6875841wwc.31 for ; Tue, 24 May 2011 04:11:58 -0700 (PDT) Received: by 10.227.209.9 with SMTP id ge9mr3274200wbb.110.1306235518018; Tue, 24 May 2011 04:11:58 -0700 (PDT) Received: from e200948.peterhouse.linaro.org (fw-lnat.cambridge.arm.com [217.140.96.63]) by mx.google.com with ESMTPS id bs4sm4695199wbb.35.2011.05.24.04.11.56 (version=SSLv3 cipher=OTHER); Tue, 24 May 2011 04:11:57 -0700 (PDT) From: Dave Martin To: patches@arm.linux.org.uk Cc: patches@linaro.org, Dave Martin Subject: [PATCH] ARM: fiq: Briefly document driver responsibilities for suspend/resume Date: Tue, 24 May 2011 12:11:48 +0100 Message-Id: <1306235508-3843-1-git-send-email-dave.martin@linaro.org> X-Mailer: git-send-email 1.7.4.1 MIME-Version: 1.0 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 --- KernelVersion: v2.6.39 diff --git a/arch/arm/include/asm/fiq.h b/arch/arm/include/asm/fiq.h index 2242ce2..d6e4b99 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