From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH] clk: qcom: Specify LE device endianness Date: Fri, 20 Nov 2015 13:14:13 -0800 Message-ID: <20151120211413.GA9555@codeaurora.org> References: <1447108254-19864-1-git-send-email-sboyd@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-clk-owner@vger.kernel.org To: Tyler Baker Cc: Mike Turquette , "linux-kernel@vger.kernel.org" , linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, Simon Arlott , Mark Brown List-Id: linux-arm-msm@vger.kernel.org On 11/20, Tyler Baker wrote: > On 9 November 2015 at 14:30, Stephen Boyd wrote: > > All these clock controllers are little endian devices, but so far > > we've been relying on the regmap mmio bus handling this for us > > without explicitly stating that fact. After commit 4a98da2164cf > > (regmap-mmio: Use native endianness for read/write, 2015-10-29), > > the regmap mmio bus will read/write with the __raw_*() IO > > accessors, instead of using the readl/writel() APIs that do > > proper byte swapping for little endian devices. > > > > So if we're running on a big endian processor and haven't > > specified the endianness explicitly in the regmap config or in > > DT, we're going to switch from doing little endian byte swapping > > to big endian accesses without byte swapping, leading to some > > confusing results. On my apq8074 dragonboard, this causes the > > device to fail to boot as we access the clock controller with > > big endian IO accesses even though the device is little endian. > > > > Specify the endianness explicitly so that the regmap core > > properly byte swaps the accesses for us. > > > > Reported-by: Kevin Hilman > > Cc: Simon Arlott > > Cc: Mark Brown > > Signed-off-by: Stephen Boyd > > Tested-by: Tyler Baker > > The kernelci.org bot also reported boot failures[1] for the > apq8016-sbc in next-20151120 with CONFIG_CPU_BIG_ENDIAN=y enabled. > I've bisected the failure down to the same offending remap-mmio patch > listed above. I've confirmed this patch applied on top of > next-20151120 fixes the boot issue for the apq8016-sbc as well. > > Any updates or comments on this patch? I'd like to see this fix in > linux-next, as it has been broken for over a week and could be masking > new issues. Yeah I've been lagging on applying patches. I need to send more patches for other regmap-mmio users too. I'll cook those up right now and send them off. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project