From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@ti.com (Santosh Shilimkar) Date: Sat, 20 Nov 2010 15:38:42 +0530 Subject: [PATCH 5/5] omap4: l2x0: Enable early BRESP bit In-Reply-To: References: <1290187866-26941-1-git-send-email-santosh.shilimkar@ti.com><1290187866-26941-2-git-send-email-santosh.shilimkar@ti.com><1290187866-26941-3-git-send-email-santosh.shilimkar@ti.com><1290187866-26941-4-git-send-email-santosh.shilimkar@ti.com><1290187866-26941-5-git-send-email-santosh.shilimkar@ti.com><1290187866-26941-6-git-send-email-santosh.shilimkar@ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > -----Original Message----- > From: M?ns Rullg?rd [mailto:mans at mansr.com] > Sent: Saturday, November 20, 2010 12:02 AM > To: Santosh Shilimkar > Cc: linux-omap at vger.kernel.org; nm at ti.com; mans at mansr.com; > tony at atomide.com; khilman at deeprootsystems.com; linux-arm- > kernel at lists.infradead.org > Subject: Re: [PATCH 5/5] omap4: l2x0: Enable early BRESP bit > > Santosh Shilimkar writes: > > > The AXI protocol specifies that the write response can only > > be sent back to an AXI master when the last write data has been > > accepted. This optimization enables the PL310 to send the write > > response of certain write transactions as soon as the store buffer > > accepts the write address. This behavior is not compatible with > > the AXI protocol and is disabled by default. You enable this > > optimization by setting the Early BRESP Enable bit in the > > Auxiliary Control Register (bit [30]). > > Did you measure the performance difference this makes, if any? > I didn't do any special runs for this bit alone. Just checked with hardware team and they confirmed that you would gain a bit on writes and it's good to enable it.