From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 4 Jan 2016 14:42:22 +0000 From: Russell King - ARM Linux To: Tero Kristo Cc: Geert Uytterhoeven , Tony Lindgren , Michael Turquette , Stephen Boyd , "linux-omap@vger.kernel.org" , linux-clk , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RFC 6/9] clk: ti: add support for omap4 module clocks Message-ID: <20160104144221.GA5783@n2100.arm.linux.org.uk> References: <1450447141-29936-1-git-send-email-t-kristo@ti.com> <1450447141-29936-7-git-send-email-t-kristo@ti.com> <20160101054815.21738.79820@quark.deferred.io> <568A20E5.6040005@ti.com> <568A735D.2060309@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <568A735D.2060309@ti.com> Sender: Russell King - ARM Linux List-ID: On Mon, Jan 04, 2016 at 03:27:57PM +0200, Tero Kristo wrote: > On 01/04/2016 12:21 PM, Geert Uytterhoeven wrote: > >FWIW, there are small loops with just a cpu_relax() in various clock drivers > >under drivers/clk/shmobile/. > > Just did a quick profiling round, and the clk_enable/disable delay loops > take anything from 0...1500ns, most typically consuming some 400-600ns. So, > based on this, dropping the udelay and adding cpu_relax instead looks like a > good change. I just verified that changing the udelay to cpu_relax works > fine also, I just need to change the bail-out period to be something sane. Was that profiling done with lockdep/lock debugging enabled or disabled? -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Mon, 4 Jan 2016 14:42:22 +0000 Subject: [RFC 6/9] clk: ti: add support for omap4 module clocks In-Reply-To: <568A735D.2060309@ti.com> References: <1450447141-29936-1-git-send-email-t-kristo@ti.com> <1450447141-29936-7-git-send-email-t-kristo@ti.com> <20160101054815.21738.79820@quark.deferred.io> <568A20E5.6040005@ti.com> <568A735D.2060309@ti.com> Message-ID: <20160104144221.GA5783@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Jan 04, 2016 at 03:27:57PM +0200, Tero Kristo wrote: > On 01/04/2016 12:21 PM, Geert Uytterhoeven wrote: > >FWIW, there are small loops with just a cpu_relax() in various clock drivers > >under drivers/clk/shmobile/. > > Just did a quick profiling round, and the clk_enable/disable delay loops > take anything from 0...1500ns, most typically consuming some 400-600ns. So, > based on this, dropping the udelay and adding cpu_relax instead looks like a > good change. I just verified that changing the udelay to cpu_relax works > fine also, I just need to change the bail-out period to be something sane. Was that profiling done with lockdep/lock debugging enabled or disabled? -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.