From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Murphy Subject: Re: [PATCH v3 1/7] dt-bindings: interconnect: Add a dma interconnect name Date: Tue, 5 Mar 2019 16:14:26 +0000 Message-ID: <0e72fbf7-b100-ddc5-3c19-32f71c37f76f@arm.com> References: <43eeca13733faefe62f9facc25b8e88f7e593f61.1549897336.git-series.maxime.ripard@bootlin.com> <553c987c-da9a-1f85-fb16-4b9fe17dd14b@linaro.org> <20190305155337.glfvgyddvnkv774m@flea> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190305155337.glfvgyddvnkv774m@flea> Content-Language: en-GB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Maxime Ripard , Georgi Djakov Cc: Mark Rutland , devicetree@vger.kernel.org, Thomas Petazzoni , Arnd Bergmann , dri-devel@lists.freedesktop.org, Paul Kocialkowski , Chen-Yu Tsai , Rob Herring , Yong Deng , Frank Rowand , Dave Martin , linux-arm-kernel@lists.infradead.org List-Id: dri-devel@lists.freedesktop.org On 05/03/2019 15:53, Maxime Ripard wrote: > Hi, > > On Fri, Mar 01, 2019 at 07:48:15PM +0200, Georgi Djakov wrote: >> On 2/11/19 17:02, Maxime Ripard wrote: >>> The current DT bindings assume that the DMA will be performed by the >>> devices through their parent DT node, and rely on that assumption for the >>> address translation using dma-ranges. >>> >>> However, some SoCs have devices that will perform DMA through another bus, >>> with separate address translation rules. We therefore need to express that >>> relationship, through the special interconnect name "dma". >>> >>> Signed-off-by: Maxime Ripard >>> --- >>> Documentation/devicetree/bindings/interconnect/interconnect.txt | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/interconnect/interconnect.txt b/Documentation/devicetree/bindings/interconnect/interconnect.txt >>> index 5a3c575b387a..e69fc2d992c3 100644 >>> --- a/Documentation/devicetree/bindings/interconnect/interconnect.txt >>> +++ b/Documentation/devicetree/bindings/interconnect/interconnect.txt >>> @@ -51,6 +51,9 @@ interconnect-names : List of interconnect path name strings sorted in the same >>> interconnect-names to match interconnect paths with interconnect >>> specifier pairs. >>> >>> + Reserved interconnect names: >>> + * dma: Path from the device to the main memory of the system >> >> Bikeshed: As it's from the device to the main memory, maybe here we can >> also denote this my calling the path dma-mem or dma-memory. For other >> paths, we are trying to mention both the source and the destination and >> maybe it would be good to be consistent although this is special one. > > I'm not sure I understand what you mean. You'd like two interconnect > names, one called dma-memory, and one memory-dma? Hmm, yes, it's not like "dma" describes an actual source or destination either :/ Robin.