From mboxrd@z Thu Jan 1 00:00:00 1970 From: felipe.contreras@gmail.com (Felipe Contreras) Date: Mon, 14 Sep 2009 15:58:24 +0300 Subject: [PATCH] arm: remove unused code in delay.S In-Reply-To: <20090914081001.GB14519@n2100.arm.linux.org.uk> References: <1252875960-21512-1-git-send-email-felipe.contreras@gmail.com> <200909132328.47079.marek.vasut@gmail.com> <20090913230008.GC30169@n2100.arm.linux.org.uk> <20090914002100.GD30621@shareable.org> <20090914081001.GB14519@n2100.arm.linux.org.uk> Message-ID: <94a0d4530909140558nd8d2c47lc9954563c80a574f@mail.gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Sep 14, 2009 at 11:10 AM, Russell King - ARM Linux wrote: > On Mon, Sep 14, 2009 at 01:21:00AM +0100, Jamie Lokier wrote: >> Russell King - ARM Linux wrote: >> > On Sun, Sep 13, 2009 at 11:28:47PM +0200, Marek Vasut wrote: >> > > > ? ? ? ? ? ? ? ? bhi ? ? __delay >> > > > ? ? ? ? ? ? ? ? mov ? ? pc, lr >> > > > ?ENDPROC(__udelay) >> > > > >> > > Hi >> > > >> > > why was this code there in the first place ? >> > >> > To make the delay loop more stable and predictable on older CPUs. >> >> So why has it been commented out, if it's needed for that? > > We moved on and it penalises later CPUs, leading to udelay providing > shorter delays than requested. > > So the choice was either stable and predictable on older CPUs but > buggy on newer CPUs, or correct on all CPUs but gives unnecessarily > longer delays on older CPUs. Why not add an #ifdef CPU_V4 or whatever? -- Felipe Contreras