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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id m17-20020a0568080f1100b002d71e151e51sm6553576oiw.0.2022.02.28.10.10.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Feb 2022 10:10:25 -0800 (PST) Sender: Guenter Roeck Message-ID: <9edce888-8e7c-9c97-dc70-17df7f348832@roeck-us.net> Date: Mon, 28 Feb 2022 10:10:23 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v2 0/2] ic2: mux: pca9541: add delayed-release support Content-Language: en-US To: Zev Weiss Cc: linux-i2c@vger.kernel.org, Peter Rosin , Rob Herring , openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Wolfram Sang References: <20220201001810.19516-1-zev@bewilderbeest.net> From: Guenter Roeck In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/28/22 09:11, Zev Weiss wrote: > On Mon, Feb 28, 2022 at 05:57:27AM PST, Guenter Roeck wrote: >> On 2/28/22 00:43, Zev Weiss wrote: >>> On Mon, Jan 31, 2022 at 04:18:08PM PST, Zev Weiss wrote: >>>> Hello, >>>> >>>> This series adds support for a new pca9541 device-tree property >>>> ("release-delay-us"), which delays releasing ownership of the bus >>>> after a transaction for a configurable duration, anticipating that >>>> another transaction may follow shortly.  By avoiding a >>>> release/reacquisition between transactions, this can provide a >>>> substantial performance improvement for back-to-back operations -- on >>>> a Delta AHE-50DC (ASPEED AST1250) system running OpenBMC with dozens >>>> of LM25066 PMICs on PCA9541-arbitrated busses, a setting of 10000 (10 >>>> ms) reduces the median latency the psusensor daemon's hwmon sysfs file >>>> reads from 2.28 ms to 0.99 ms (a 57% improvement). >>>> >>> >>> Ping...Guenter, any thoughts on this? >>> >> >> It sounds reasonable to me, but I don't have access to hardware anymore >> to test it, so I have no means to confirm that it actually works. >> > > Ack, thanks.  In that case, what's the path forward on getting changes to this driver merged?  I see sign-offs from Wolfram and Peter on the last few commits that touched it -- any input from the i2c/i2c-mux maintainers? > The i2c/i2c-mux maintainers will need to accept it, and you'll need approval for the DT changes from a DT maintainer (presumably Rob). Guenter