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[188.155.176.92]) by smtp.gmail.com with ESMTPSA id e1-20020a1709062c0100b006f3ef214dafsm4714932ejh.21.2022.05.08.23.48.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 08 May 2022 23:48:53 -0700 (PDT) Message-ID: <41d6b00f-d8ac-ca54-99db-ea99c9049e0a@linaro.org> Date: Mon, 9 May 2022 08:48:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH v3 5/6] dt-bindings: net: dsa: make reset optional and add rgmii-mode to mt7531 Content-Language: en-US To: Peter Geis , Frank Wunderlich Cc: Heiko Stuebner , "open list:ARM/Rockchip SoC..." , Frank Wunderlich , linux-mediatek@lists.infradead.org, Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Matthias Brugger , Sean Wang , Landen Chao , DENG Qingfang , Linux Kernel Network Developers , devicetree , arm-mail-list , Linux Kernel Mailing List , Greg Ungerer , =?UTF-8?Q?Ren=c3=a9_van_Dorst?= , Mauro Carvalho Chehab References: <20220507170440.64005-1-linux@fw-web.de> <06157623-4b9c-6f26-e963-432c75cfc9e5@linaro.org> <2509116.Lt9SDvczpP@phil> From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 08/05/2022 19:04, Peter Geis wrote: > On Sun, May 8, 2022 at 8:12 AM Frank Wunderlich wrote: >>> >>> I think the issue is more for the description itself. >>> >>> Devicetree is only meant to describe the hardware and does in general don't >>> care how any firmware (Linux-kernel, *BSD, etc) handles it. So going with >>> "the kernel does it this way" is not a valid reason for a binding change ;-) . Exactly. The argument in commit msg was not matching the change, because driver implementation should not be (mostly) a reason for such changes. >>> >>> Instead in general want to reason that there are boards without this reset >>> facility and thus make it optional for those. >> >> if only the wording is the problem i try to rephrase it from hardware PoV. >> >> maybe something like this? >> >> https://github.com/frank-w/BPI-R2-4.14/commits/5.18-mt7531-mainline2/Documentation/devicetree/bindings/net/dsa/mediatek%2Cmt7530.yaml Looks ok. >> >> Another way is maybe increasing the delay after the reset (to give more time all >> come up again), but imho it is no good idea resetting the gmac/mdio-bus from the >> child device. >> >> have not looked into the gmac driver if this always does the initial reset to >> have a "clean state". In this initial reset the switch will be resetted too >> and does not need an additional one which needs the gmac/mdio initialization >> to be done again. > > For clarification, the reset gpio line is purely to reset the phy. > If having the switch driver own the reset gpio instead of the gmac > breaks initialization that means there's a bug in the gmac driver > handling phy init. > In testing I've seen issues moving the reset line to the mdio node > with other phys and the stmmac gmac driver, so I do believe this is > the case. Yes, this seems reasonable, although Frank mentioned that reset is shared with gmac, so it resets some part of it as well? Best regards, Krzysztof