Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932814Ab2JWKLZ (ORCPT ); Tue, 23 Oct 2012 06:11:25 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:51330 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756970Ab2JWKLX (ORCPT ); Tue, 23 Oct 2012 06:11:23 -0400 MIME-Version: 1.0 In-Reply-To: <1350906877-19410-1-git-send-email-balbi@ti.com> References: <1350906877-19410-1-git-send-email-balbi@ti.com> Date: Tue, 23 Oct 2012 12:11:21 +0200 Message-ID: Subject: Re: [PATCH] arm: sched: stop sched_clock() during suspend From: Linus Walleij To: Felipe Balbi Cc: Russell King , Linux ARM Kernel Mailing List , Linux OMAP Mailing List , Linux Kernel Mailing List , Kevin Hilman , Paul Walmsley , Tony Lindgren , Santosh Shilimkar Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1501 Lines: 37 On Mon, Oct 22, 2012 at 1:54 PM, Felipe Balbi wrote: > The scheduler imposes a requirement to sched_clock() > which is to stop the clock during suspend, if we don't > do that IRQ threads will be rescheduled in the future > which might cause transfers to timeout depending on > how driver is written. > > This became an issue on OMAP when we converted omap-i2c.c > to use threaded IRQs, it turned out that depending on how > much time we spent on suspend, the I2C IRQ thread would > end up being rescheduled so far in the future that I2C > transfers would timeout and, because omap_hsmmc depends > on an I2C-connected device to detect if an MMC card is > inserted in the slot, our rootfs would just vanish. > > arch/arm/kernel/sched_clock.c already had an optional > implementation (sched_clock_needs_suspend()) which would > handle scheduler's requirement properly, what this patch > does is simply to make that implementation non-optional. > > This has been tested with beagleboard XM (OMAP3630) and > pandaboard rev A3 (OMAP4430). Suspend to RAM is now working > after this patch. > > Signed-off-by: Felipe Balbi After Russell explains so I get it: Acked-by: Linus Walleij Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/