From: Peter Rosin <peda@axentia.se>
To: linux-kernel@vger.kernel.org
Cc: Peter Rosin <peda@axentia.se>, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Russell King <linux@armlinux.org.uk>,
Guenter Roeck <linux@roeck-us.net>,
Jean Delvare <jdelvare@suse.com>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-hwmon@vger.kernel.org
Subject: [PATCH 0/2] Sluggish AT91 I2C driver causes SMBus timeouts
Date: Fri, 13 Oct 2017 11:27:03 +0200 [thread overview]
Message-ID: <20171013092705.7038-1-peda@axentia.se> (raw)
Hi!
This is a workaround for a problem in the AT91 I2C adapter driver
(or perhaps the hardware?) when it drives the TWI peripheral on an
Atmel sama5d3 chip as I2C.
Apparently, that driver can delay in excess of 100 ms just after
the transfer of the 7th bit of the last byte. When it does this
the I2C bus, when viewed from SMBUS client devices, appears
stuck with SCL low. Some SMBUS devices times out under these
conditions, in particular temperature sensors. The I2C adapter
driver does however not notice the timeout, and thinks the transfer
completed successfully when it finally desides to finish the
transaction. When this happens, the 8th bit of the last byte is
always set, and thus quite possibly corrupted.
The chip this was observed with (an nxp SE97) has a means to disable
the SMBUS timeout detector, which "fixes" things. Do that.
This should probably go to stable?
Previous discussion: https://lkml.org/lkml/2017/10/12/227
Cheers,
Peter
Peter Rosin (2):
hwmon: (jc42) optionally try to disable the SMBUS timeout
ARM: dts: at91: disable the nxp,se97b SMBUS timeout on the TSE-850
Documentation/devicetree/bindings/hwmon/jc42.txt | 4 ++++
arch/arm/boot/dts/at91-tse850-3.dts | 1 +
drivers/hwmon/jc42.c | 20 ++++++++++++++++++++
3 files changed, 25 insertions(+)
--
2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: peda@axentia.se (Peter Rosin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/2] Sluggish AT91 I2C driver causes SMBus timeouts
Date: Fri, 13 Oct 2017 11:27:03 +0200 [thread overview]
Message-ID: <20171013092705.7038-1-peda@axentia.se> (raw)
Hi!
This is a workaround for a problem in the AT91 I2C adapter driver
(or perhaps the hardware?) when it drives the TWI peripheral on an
Atmel sama5d3 chip as I2C.
Apparently, that driver can delay in excess of 100 ms just after
the transfer of the 7th bit of the last byte. When it does this
the I2C bus, when viewed from SMBUS client devices, appears
stuck with SCL low. Some SMBUS devices times out under these
conditions, in particular temperature sensors. The I2C adapter
driver does however not notice the timeout, and thinks the transfer
completed successfully when it finally desides to finish the
transaction. When this happens, the 8th bit of the last byte is
always set, and thus quite possibly corrupted.
The chip this was observed with (an nxp SE97) has a means to disable
the SMBUS timeout detector, which "fixes" things. Do that.
This should probably go to stable?
Previous discussion: https://lkml.org/lkml/2017/10/12/227
Cheers,
Peter
Peter Rosin (2):
hwmon: (jc42) optionally try to disable the SMBUS timeout
ARM: dts: at91: disable the nxp,se97b SMBUS timeout on the TSE-850
Documentation/devicetree/bindings/hwmon/jc42.txt | 4 ++++
arch/arm/boot/dts/at91-tse850-3.dts | 1 +
drivers/hwmon/jc42.c | 20 ++++++++++++++++++++
3 files changed, 25 insertions(+)
--
2.11.0
next reply other threads:[~2017-10-13 9:27 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-13 9:27 Peter Rosin [this message]
2017-10-13 9:27 ` [PATCH 0/2] Sluggish AT91 I2C driver causes SMBus timeouts Peter Rosin
2017-10-13 9:27 ` [PATCH 1/2] hwmon: (jc42) optionally try to disable the SMBUS timeout Peter Rosin
2017-10-13 9:27 ` Peter Rosin
2017-10-13 9:27 ` Peter Rosin
2017-10-13 12:51 ` Guenter Roeck
2017-10-13 12:51 ` Guenter Roeck
2017-10-13 13:50 ` Guenter Roeck
2017-10-13 13:50 ` Guenter Roeck
2017-10-13 14:26 ` Peter Rosin
2017-10-13 14:26 ` Peter Rosin
2017-10-13 20:35 ` Guenter Roeck
2017-10-13 20:35 ` Guenter Roeck
2017-10-13 23:44 ` Guenter Roeck
2017-10-13 23:44 ` Guenter Roeck
2017-10-17 22:16 ` Rob Herring
2017-10-17 22:16 ` Rob Herring
2017-10-18 2:38 ` Guenter Roeck
2017-10-18 2:38 ` Guenter Roeck
2017-10-26 6:44 ` Peter Rosin
2017-10-26 6:44 ` Peter Rosin
2017-10-26 6:44 ` Peter Rosin
2017-10-26 13:45 ` Guenter Roeck
2017-10-26 13:45 ` Guenter Roeck
2017-10-26 13:45 ` Guenter Roeck
2017-10-13 9:27 ` [PATCH 2/2] ARM: dts: at91: disable the nxp,se97b SMBUS timeout on the TSE-850 Peter Rosin
2017-10-13 9:27 ` [PATCH 2/2] ARM: dts: at91: disable the nxp, se97b " Peter Rosin
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