Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752560AbaKJKXU (ORCPT ); Mon, 10 Nov 2014 05:23:20 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:55375 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890AbaKJKXS (ORCPT ); Mon, 10 Nov 2014 05:23:18 -0500 Date: Mon, 10 Nov 2014 10:23:08 +0000 From: Catalin Marinas To: Mark Salter Cc: Feng Kan , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "patches@apm.com" , Bao Truong Subject: Re: [PATCH RESEND 1/7] arm64: dts: Add APM X-Gene USB DTS node Message-ID: <20141110102308.GB21366@e104818-lin.cambridge.arm.com> References: <1414438108-8384-1-git-send-email-fkan@apm.com> <1414438108-8384-2-git-send-email-fkan@apm.com> <1414599817.1870.15.camel@deneb.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1414599817.1870.15.camel@deneb.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 29, 2014 at 04:23:37PM +0000, Mark Salter wrote: > On Mon, 2014-10-27 at 12:28 -0700, Feng Kan wrote: > > This parch adds the device tree nodes for APM X-Gnene USB host controller. > > Since X-Gene SOC supports maximum 2 USB ports, 2 dts node are added. > > > > Signed-off-by: Bao Truong > > Signed-off-by: Feng Kan > > --- > > arch/arm64/boot/dts/apm-storm.dtsi | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/arch/arm64/boot/dts/apm-storm.dtsi b/arch/arm64/boot/dts/apm-storm.dtsi > > index 3eef74b..a80f2fa 100644 > > --- a/arch/arm64/boot/dts/apm-storm.dtsi > > +++ b/arch/arm64/boot/dts/apm-storm.dtsi > > @@ -587,6 +587,20 @@ > > phy-names = "sata-phy"; > > }; > > > > + usb0: dwusb@19000000 { > > + status = "disabled"; > > + compatible = "xhci-platform"; > > + reg = <0x0 0x19000000 0x0 0x100000>; > > + interrupts = <0x0 0x89 0x4>; > > + }; > > + > > + usb1: dwusb@19800000 { > > + status = "disabled"; > > + compatible = "xhci-platform"; > > + reg = <0x0 0x19800000 0x0 0x100000>; > > + interrupts = <0x0 0x8a 0x4>; > > + }; > > + > > Should these have "dma-coherent" properties? Just a note here: if the device is coherent but the DT does not specify it as such, it's not just a matter of performance but potentially data corruption. The current DMA ops for non-coherent devices perform a D-cache invalidate on the unmap path with the FROM_DEVICE direction. If the device is coherent and the DMA transfer (FROM_DEVICE) allocated data in the system cache (L3), the CPU cache invalidation after the transfer would corrupt such data. We had a similar discussion internally around coherency properties for ACPI. If we don't have guarantees that the DT (or ACPI) tables always pass the correct information, we should change the kernel DMA ops to perform the safe clean+invalidate on the unmap path (some CPU implementations do this by default). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/