From mboxrd@z Thu Jan 1 00:00:00 1970 From: Georgi Djakov Subject: Re: [PATCH v3 1/7] dt-bindings: interconnect: Add a dma interconnect name Date: Thu, 7 Mar 2019 17:15:20 +0200 Message-ID: <477995b0-9ac3-b6ca-f5f2-856e4af926f1@linaro.org> References: <43eeca13733faefe62f9facc25b8e88f7e593f61.1549897336.git-series.maxime.ripard@bootlin.com> <553c987c-da9a-1f85-fb16-4b9fe17dd14b@linaro.org> <20190305155337.glfvgyddvnkv774m@flea> <0e72fbf7-b100-ddc5-3c19-32f71c37f76f@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <0e72fbf7-b100-ddc5-3c19-32f71c37f76f@arm.com> Content-Language: en-US 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: Robin Murphy , Maxime Ripard 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 Hi, On 3/5/19 18:14, Robin Murphy wrote: > 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 >>>> --- >>>> =A0 Documentation/devicetree/bindings/interconnect/interconnect.txt | >>>> 3 +++ >>>> =A0 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 >>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 interconnect-names to match= interconnect paths with >>>> interconnect >>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 specifier pairs. >>>> =A0 +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Rese= rved interconnect names: >>>> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0 * 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 :/ IIUC, it's a path (bus) that a dma device use to access some memory (read or/and write). So i have used source-destination above more in the sense of initiator-target or master-slave. My suggestion was just to change the reserved interconnect name from "dma" to "dma-mem" or "dma-memory". Thanks, Georgi