linux-kernel - Re: [PATCH v2 0/2] ic2: mux: pca9541: add delayed-release support

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Message-ID: <YhyLIRFbs226KTwA@hatter.bewilderbeest.net>
Date:   Mon, 28 Feb 2022 00:43:13 -0800
From:   Zev Weiss <zev@...ilderbeest.net>
To:     linux-i2c@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Peter Rosin <peda@...ntia.se>, Rob Herring <robh+dt@...nel.org>
Cc:     openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 0/2] ic2: mux: pca9541: add delayed-release support

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?


Thanks,
Zev