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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH 02/11] dt-bindings: serial: snps-dw-apb-uart: Relax dma-names order constraint Content-Language: en-US To: Conor Dooley , Krzysztof Kozlowski Cc: Sudeep Holla , Cristian Marussi , Rob Herring , Krzysztof Kozlowski , Greg Kroah-Hartman , Liam Girdwood , Mark Brown , Nicolas Frattaroli , Heiko Stuebner , Jaroslav Kysela , Takashi Iwai , Paul Walmsley , Palmer Dabbelt , Albert Ou , Daniel Drake , Katsuhiro Suzuki , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, alsa-devel@alsa-project.org, linux-rockchip@lists.infradead.org, linux-riscv@lists.infradead.org, kernel@collabora.com References: <20230315114806.3819515-1-cristian.ciocaltea@collabora.com> <20230315114806.3819515-3-cristian.ciocaltea@collabora.com> <3679f2d0-55f0-1710-abc2-b268b6fc6969@linaro.org> <8ae57fe3-56aa-7e50-3eaa-a12a40657baf@collabora.com> <80796828-7b38-184a-2e8e-3cfe9158b67f@linaro.org> <13cb8dbd-994c-4b38-b715-44a3bf3d278d@spud> From: Cristian Ciocaltea In-Reply-To: <13cb8dbd-994c-4b38-b715-44a3bf3d278d@spud> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230317_104359_227801_89F5EFD9 X-CRM114-Status: GOOD ( 19.85 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On 3/17/23 18:26, Conor Dooley wrote: > On Fri, Mar 17, 2023 at 04:54:47PM +0100, Krzysztof Kozlowski wrote: >> On 17/03/2023 11:21, Cristian Ciocaltea wrote: >>> On 3/17/23 10:31, Krzysztof Kozlowski wrote: >>>> On 15/03/2023 12:47, Cristian Ciocaltea wrote: >>>>> Commit 370f696e4474 ("dt-bindings: serial: snps-dw-apb-uart: add dma & >>>>> dma-names properties") documented dma-names property to handle Allwiner >>>>> D1 dtbs_check warnings, but relies on a strict rx->tx ordering, which is >>>>> the reverse of what a different board expects: >>>>> >>>>> rk3326-odroid-go2.dtb: serial@ff030000: dma-names:0: 'rx' was expected >>>>> >>>>> A quick and incomplete check shows the inconsistency is present in many >>>>> other DT files: >>>> >>>> Why not fixing the DTS? The properties should have fixed order. >>> >>> I was initially concerned about the risk of a potential ABI breakage, >>> but I think that's not really a problem since dma-names is not directly >>> accessed in the driver and DT Kernel API doesn't rely on a particular order. >>> >>> If there are no objections, I would switch the order in the binding to >>> tx->rx, since that's what most of the DTS use, and fix the remaining ones. >> >> Since we added the order recently, I rather assume it is the correct or >> preferred one. > > IIRC I checked around the other serial bindings & there was not a > consistent order that all serial bindings used, so I picked the order that > was used across the various allwinner boards that do use dma-names. Thanks for clarifying this, Conor! Would it be fine to switch to tx->rx order as it requires less changes to fix the inconsistencies? > Before changing dts files, it's probably a good idea to make sure that > the dma-names are not used somewhere outside of Linux. Right, that means we cannot exclude the ABI breakage concern. Not sure how easy would be to actually verify this. Hence I wonder if there is really no chance to allow the flexible order in the binding.. > Cheers, > Conor _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv