From mboxrd@z Thu Jan 1 00:00:00 1970 From: skannan@codeaurora.org (Saravana Kannan) Date: Fri, 04 Mar 2011 15:48:45 -0800 Subject: [PATCHv4 0/4] ARM: Fixing udelay() for SMP and non-SMP systems In-Reply-To: References: <1292883633-19553-1-git-send-email-sboyd@codeaurora.org> Message-ID: <4D717A5D.8010608@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 03/04/2011 02:10 AM, Linus Walleij wrote: > 2010/12/20 Stephen Boyd: > >> These patches fix the udelay() issue pointed out on >> arm-lkml[1][2]. A quick recap: some SMP machines can scale >> their CPU frequencies independent of one another. loops_per_jiffy >> is calibrated globally and used in __const_udelay(). If one CPU >> is running faster than what the loops_per_jiffy is calculated >> (or scaled) for, udelay() will be incorrect and not wait long >> enough (or too long). A similar problem occurs if the cpu >> frequency is scaled during a udelay() call. > > Hwt's happening to this patch set? We have applied it and > implemented a timer for the U8500. > > Tested-by: Linus Walleij > > Mattias WALLIN can probably also provide a Tested-by: > from ST-Ericsson if it helps. > > Generally I think this is good and important stuff that should > be merged, will you be submitting it to Russells patch tracker > or pull request for 2.6.39? > Thanks for testing and reporting it Linus. We are certainly interested in getting this in. If I'm not mistaken, the last time we sent it out, there was a C vs. assembly argument and got side tracked or no one acked or responded to it. Will try to send out the patches again within the next few weeks. Thanks, Saravana -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.