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bh=9y6LmXOwEW312Rhq3CPGU89SHAaxq5yj0JeMnIHrcaM=; b=Dsn444WMSDhfhI8VX8x3HzCDRTs16AZkb1Ha9J3yyjaaV2NaDkz8nkd5fDlCvTueG4 pv5LmWjj0Dj26Hi221aBGlgPJYyoWP6yLIQSWM3V+yNfOhjhi7OgrZoFnjtlL4VteVNd 5QXaZOHbFQKRE4qK0GC2o9KOVShwNxd0RrI6e+vAf7WiJENSM2c85kumaWxI66ognimf HmRogGgmXVumafFsiaKMNmjHCam7WNYEcQCRZqJn1czaPB+D8mCneCpVe42hsKJJfpO+ dlFiFqozUYw8BOBmMJy2VRYYkKLXA0ML6q2cY9CburcL4shnfm+zBUCfoqhdDk5VFgDo OBhg== X-Gm-Message-State: AOJu0YymhGrT8+yKZJNLqiAjIVYlcd3a4lCAjPMOR+aIvvIxlJKkJRZp MM3tHamrGaIbf7O8DSfYMX8uKQ== X-Google-Smtp-Source: AGHT+IFRkexNgJpWRS+yzP5zEwgjOKhCx1ox+0JLdEC7upd7ErsJaMQzzXQMoPegeOn4fsR2Ozjmew== X-Received: by 2002:a2e:1454:0:b0:2c5:169f:ff03 with SMTP id 20-20020a2e1454000000b002c5169fff03mr1592852lju.5.1698405957743; Fri, 27 Oct 2023 04:25:57 -0700 (PDT) Received: from [192.168.0.22] ([78.10.206.168]) by smtp.gmail.com with ESMTPSA id d21-20020a2eb055000000b002c004175d26sm250041ljl.56.2023.10.27.04.25.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Oct 2023 04:25:57 -0700 (PDT) Message-ID: <7bfa2f6c-3e99-49a6-9b5a-81398d4bce7e@linaro.org> Date: Fri, 27 Oct 2023 13:25:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/2] dt-bindings: i2c: mv64xxx: add bus-reset-gpios property Content-Language: en-US To: Wolfram Sang , Chris Packham , krzysztof.kozlowski+dt@linaro.org, gregory.clement@bootlin.com, andi.shyti@kernel.org, robh+dt@kernel.org, conor+dt@kernel.org, linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Abel Vesa References: <20231027033104.1348921-1-chris.packham@alliedtelesis.co.nz> <20231027033104.1348921-2-chris.packham@alliedtelesis.co.nz> From: Krzysztof Kozlowski Autocrypt: addr=krzysztof.kozlowski@linaro.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/10/2023 11:09, Wolfram Sang wrote: > On Fri, Oct 27, 2023 at 04:31:03PM +1300, Chris Packham wrote: >> Add bus-reset-gpios and bus-reset-duration-us properties to the >> marvell,mv64xxx-i2c binding. These can be used to describe hardware >> where a common reset GPIO is connected to all downstream devices on and >> I2C bus. This reset will be asserted then released before the downstream >> devices on the bus are probed. >> >> Signed-off-by: Chris Packham >> Reviewed-by: Krzysztof Kozlowski > > Krzysztof, are you fine with this change? Actually no. NAK. Not because of the naming, but because the new name triggered some new paths in my brain which brought the point - this is old problem of power sequencing of children. I believe this must be solved in more generic way. First - generic for all I2C devices. Second - generic also matching other buses/subsystems, which have similar problem. We did it for USB (onboard USB), MMC (unloved MMC power sequence) and now we are doing it for PCIe and few others (Cc: Abel) https://lpc.events/event/17/contributions/1507/ Current solution is heavily limited. What about regulators? What about buses having 2 reset lines (still the same bus)? What about sequence? Best regards, Krzysztof