From: Chris Packham <Chris.Packham@alliedtelesis.co.nz> To: Guenter Roeck <linux@roeck-us.net>, "jdelvare@suse.com" <jdelvare@suse.com> Cc: "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>, "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org> Subject: Re: Errant readings on LM81 with T2080 SoC Date: Mon, 8 Mar 2021 20:27:30 +0000 [thread overview] Message-ID: <d6074923-ee7e-4499-0e54-383a607d3c41@alliedtelesis.co.nz> (raw) In-Reply-To: <5709f180-04b5-09b2-e1c4-53eb5c9345d8@roeck-us.net> On 8/03/21 5:59 pm, Guenter Roeck wrote: > On 3/7/21 8:37 PM, Chris Packham wrote: > [ ... ] >>> That's from -ENXIO which is used in only one place in i2c-mpc.c. I'll >>> enable some debug and see what we get. >> For the errant readings there was nothing abnormal reported by the driver. >> >> For the "No such device or address" I saw "mpc-i2c ffe119000.i2c: No >> RXAK" which matches up with the -ENXIO return. >> > Id suggest to check the time until not busy and stop in mpc_xfer(). > Those hot loops are unusual, and may well mess up the code especially > if preempt is enabled. Also, are you using interrupts or polling in > your system ? I'm using interrupts but I see the same issue if I comment out the interrupts in the dtsi file (i.e. force it to use polling). > The interrupt handler looks a bit odd, with "Read again > to allow register to stabilise". Yeah that stuck out to me too. The code in question predates git, I went spelunking in history.git and the "Read again" seems to be in the initial version[0]. I did try to alter the interrupt handler so that it only does one read but that didn't seem to change anything. > Do you have fsl,timeout set in the devicetree properties and, if so, > have you played with it ? Haven't got it set but I'll have a go at tweaking it. > Other than that, the only other real idea I have would be to monitor > the i2c bus. I am in the fortunate position of being able to go into the office and even happen to have the expensive scope at the moment. Now I just need to find a tame HW engineer so I don't burn myself trying to attach the probes. -- [0] - https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=11b3235dc04a306f6a9ba14c1ab621b2d54f2c56
WARNING: multiple messages have this Message-ID (diff)
From: Chris Packham <Chris.Packham@alliedtelesis.co.nz> To: Guenter Roeck <linux@roeck-us.net>, "jdelvare@suse.com" <jdelvare@suse.com> Cc: "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>, "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org> Subject: Re: Errant readings on LM81 with T2080 SoC Date: Mon, 8 Mar 2021 20:27:30 +0000 [thread overview] Message-ID: <d6074923-ee7e-4499-0e54-383a607d3c41@alliedtelesis.co.nz> (raw) In-Reply-To: <5709f180-04b5-09b2-e1c4-53eb5c9345d8@roeck-us.net> On 8/03/21 5:59 pm, Guenter Roeck wrote: > On 3/7/21 8:37 PM, Chris Packham wrote: > [ ... ] >>> That's from -ENXIO which is used in only one place in i2c-mpc.c. I'll >>> enable some debug and see what we get. >> For the errant readings there was nothing abnormal reported by the driver. >> >> For the "No such device or address" I saw "mpc-i2c ffe119000.i2c: No >> RXAK" which matches up with the -ENXIO return. >> > Id suggest to check the time until not busy and stop in mpc_xfer(). > Those hot loops are unusual, and may well mess up the code especially > if preempt is enabled. Also, are you using interrupts or polling in > your system ? I'm using interrupts but I see the same issue if I comment out the interrupts in the dtsi file (i.e. force it to use polling). > The interrupt handler looks a bit odd, with "Read again > to allow register to stabilise". Yeah that stuck out to me too. The code in question predates git, I went spelunking in history.git and the "Read again" seems to be in the initial version[0]. I did try to alter the interrupt handler so that it only does one read but that didn't seem to change anything. > Do you have fsl,timeout set in the devicetree properties and, if so, > have you played with it ? Haven't got it set but I'll have a go at tweaking it. > Other than that, the only other real idea I have would be to monitor > the i2c bus. I am in the fortunate position of being able to go into the office and even happen to have the expensive scope at the moment. Now I just need to find a tame HW engineer so I don't burn myself trying to attach the probes. -- [0] - https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=11b3235dc04a306f6a9ba14c1ab621b2d54f2c56
next prev parent reply other threads:[~2021-03-08 20:28 UTC|newest] Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-07 22:52 Errant readings on LM81 with T2080 SoC Chris Packham 2021-03-07 22:52 ` Chris Packham 2021-03-08 0:31 ` Guenter Roeck 2021-03-08 0:31 ` Guenter Roeck 2021-03-08 2:27 ` Chris Packham 2021-03-08 2:27 ` Chris Packham 2021-03-08 4:37 ` Chris Packham 2021-03-08 4:37 ` Chris Packham 2021-03-08 4:59 ` Guenter Roeck 2021-03-08 4:59 ` Guenter Roeck 2021-03-08 20:27 ` Chris Packham [this message] 2021-03-08 20:27 ` Chris Packham 2021-03-08 22:39 ` Guenter Roeck 2021-03-08 22:39 ` Guenter Roeck 2021-03-10 2:19 ` Chris Packham 2021-03-10 2:19 ` Chris Packham 2021-03-10 5:06 ` Guenter Roeck 2021-03-10 5:06 ` Guenter Roeck 2021-03-10 21:48 ` Chris Packham 2021-03-10 21:48 ` Chris Packham 2021-03-11 7:41 ` Guenter Roeck 2021-03-11 7:41 ` Guenter Roeck 2021-03-11 8:18 ` Wolfram Sang 2021-03-11 8:18 ` Wolfram Sang 2021-03-11 15:19 ` Guenter Roeck 2021-03-11 15:19 ` Guenter Roeck 2021-03-11 21:17 ` Chris Packham 2021-03-11 21:17 ` Chris Packham 2021-03-11 21:34 ` Guenter Roeck 2021-03-11 21:34 ` Guenter Roeck 2021-03-11 23:47 ` Chris Packham 2021-03-11 23:47 ` Chris Packham 2021-03-12 0:07 ` Guenter Roeck 2021-03-12 0:07 ` Guenter Roeck 2021-03-12 0:19 ` Chris Packham 2021-03-12 0:19 ` Chris Packham 2021-03-12 9:25 ` David Laight 2021-03-14 21:26 ` Chris Packham 2021-03-15 9:46 ` David Laight 2021-03-18 5:44 ` Wolfram Sang 2021-03-18 5:44 ` Wolfram Sang 2021-03-18 3:46 ` Chris Packham 2021-03-18 3:46 ` Chris Packham 2021-03-18 4:02 ` Guenter Roeck 2021-03-18 4:02 ` Guenter Roeck 2021-03-18 5:39 ` Wolfram Sang 2021-03-18 5:39 ` Wolfram Sang 2021-03-08 22:10 ` Chris Packham 2021-03-08 22:10 ` Chris Packham 2021-03-09 4:36 ` Chris Packham 2021-03-09 4:36 ` Chris Packham 2021-03-09 5:24 ` Guenter Roeck 2021-03-09 5:24 ` Guenter Roeck 2021-03-09 23:35 ` Chris Packham 2021-03-09 23:35 ` Chris Packham 2021-03-10 3:29 ` Guenter Roeck 2021-03-10 3:29 ` Guenter Roeck
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