From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] ARM: decompressor: reset ttbcr fields to use TTBR0 on ARMv7 Date: Mon, 12 Sep 2016 11:23:53 +0100 Message-ID: <20160912102352.GU1041@n2100.armlinux.org.uk> References: <57D3C06D.4030908@codeaurora.org> <1473663420-18629-1-git-send-email-sramana@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from pandora.armlinux.org.uk ([78.32.30.218]:35915 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757224AbcILK0M (ORCPT ); Mon, 12 Sep 2016 06:26:12 -0400 Content-Disposition: inline In-Reply-To: <1473663420-18629-1-git-send-email-sramana@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Srinivas Ramana Cc: nicolas.pitre@linaro.org, will.deacon@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org On Mon, Sep 12, 2016 at 12:27:00PM +0530, Srinivas Ramana wrote: > If the bootloader uses the long descriptor format and jumps to > kernel decompressor code, TTBCR may not be in a right state. > Before enabling the MMU, it is required to clear the TTBCR.PD0 > field to use TTBR0 for translation table walks. > > The 'commit dbece45894d3a ("ARM: 7501/1: decompressor: > reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but There's no need to single-quote the commit part of this sentence. > doesn't consider all the bits for the size of TTBCR.N. > > Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to > indicate the use of TTBR0 and the correct base address width. > Adding a properly formatted Fixes: line here would be a bonus if we need to backport it to stable trees. > Signed-off-by: Srinivas Ramana > --- > arch/arm/boot/compressed/head.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S > index af11c2f8f3b7..fc6d541549a2 100644 > --- a/arch/arm/boot/compressed/head.S > +++ b/arch/arm/boot/compressed/head.S > @@ -779,7 +779,7 @@ __armv7_mmu_cache_on: > orrne r0, r0, #1 @ MMU enabled > movne r1, #0xfffffffd @ domain 0 = client > bic r6, r6, #1 << 31 @ 32-bit translation system > - bic r6, r6, #3 << 0 @ use only ttbr0 > + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0 Provided this is correct (I've not checked, I'd like an ack from one of the ARM people, and I'd prefer to see a tested-by as well), and the above points are addressed, it can be dropped into the patch system. Thanks. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.