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From: Zev Weiss <zev@bewilderbeest.net>
To: linux-i2c@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
 Peter Rosin <peda@axentia.se>, Rob Herring <robh+dt@kernel.org>
Subject: [PATCH v2 0/2] ic2: mux: pca9541: add delayed-release support
Date: Mon, 31 Jan 2022 16:18:08 -0800
Message-Id: <20220201001810.19516-1-zev@bewilderbeest.net>
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Cc: devicetree@vger.kernel.org, openbmc@lists.ozlabs.org,
 linux-kernel@vger.kernel.org, Zev Weiss <zev@bewilderbeest.net>
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 <openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org>

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).


Thanks,
Zev

Changes since v1 [0]:
 - removed spurious #include line from dt-bindings example

[0] https://lore.kernel.org/linux-i2c/20220124213850.3766-1-zev@bewilderbeest.net/

Zev Weiss (2):
  i2c: mux: pca9541: add delayed-release support
  dt-bindings: i2c: add nxp,pca9541 release-delay-us property

 .../devicetree/bindings/i2c/nxp,pca9541.txt   |  9 +++
 drivers/i2c/muxes/i2c-mux-pca9541.c           | 56 ++++++++++++++++---
 2 files changed, 56 insertions(+), 9 deletions(-)

-- 
2.34.1