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From: Jean Delvare <jdelvare@suse.de>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Robert Rosengren <robert.rosengren@axis.com>,
	lm-sensors@lm-sensors.org, Johan Adolfsson <johana@axis.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [lm-sensors] [PATCH] hwmon: (ads7828) Make sample interval configurable
Date: Tue, 27 Jan 2015 23:34:55 +0100	[thread overview]
Message-ID: <20150127233455.0c62457e@endymion.delvare> (raw)
In-Reply-To: <20150127200553.GA5689@roeck-us.net>

On Tue, 27 Jan 2015 12:05:53 -0800, Guenter Roeck wrote:
> On Tue, Jan 27, 2015 at 08:54:34PM +0100, Robert Rosengren wrote:
> > Guenter and Jean, 
> > 
> > To sum up, my problems was related my kernel and hardware configuration, and it now works. Many thanks for your input!
> > 
> > However, the values retrieved from hwmon sysfs is not the same as before the regmap patch. Guenter, the byte swap for the regval retrieved by regmap_read. In what order is the bits returned from that function, because it seems as if I disabled that code I get values as I expect (i.e. before the regmap patch).
> > 
> Trying to understand. Are you saying everything works as expected
> if you keep byte_swap set to false ?
> 
> That might well be, though it might mean that regmap has a bug
> in how it treats i2c word read operations. I'll have to look into it 
> some more.

Remember that SMBus specifies that the LSB comes first (and i2c-core
implement things that way) while real I2C devices typically send the MSB
first. This has always caused confusion. This is why a lot of drivers
need byte-swapping.

-- 
Jean Delvare
SUSE L3 Support

WARNING: multiple messages have this Message-ID (diff)
From: Jean Delvare <jdelvare@suse.de>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Robert Rosengren <robert.rosengren@axis.com>,
	lm-sensors@lm-sensors.org, Johan Adolfsson <johana@axis.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [lm-sensors] [PATCH] hwmon: (ads7828) Make sample interval configurable
Date: Tue, 27 Jan 2015 22:34:55 +0000	[thread overview]
Message-ID: <20150127233455.0c62457e@endymion.delvare> (raw)
In-Reply-To: <20150127200553.GA5689@roeck-us.net>

On Tue, 27 Jan 2015 12:05:53 -0800, Guenter Roeck wrote:
> On Tue, Jan 27, 2015 at 08:54:34PM +0100, Robert Rosengren wrote:
> > Guenter and Jean, 
> > 
> > To sum up, my problems was related my kernel and hardware configuration, and it now works. Many thanks for your input!
> > 
> > However, the values retrieved from hwmon sysfs is not the same as before the regmap patch. Guenter, the byte swap for the regval retrieved by regmap_read. In what order is the bits returned from that function, because it seems as if I disabled that code I get values as I expect (i.e. before the regmap patch).
> > 
> Trying to understand. Are you saying everything works as expected
> if you keep byte_swap set to false ?
> 
> That might well be, though it might mean that regmap has a bug
> in how it treats i2c word read operations. I'll have to look into it 
> some more.

Remember that SMBus specifies that the LSB comes first (and i2c-core
implement things that way) while real I2C devices typically send the MSB
first. This has always caused confusion. This is why a lot of drivers
need byte-swapping.

-- 
Jean Delvare
SUSE L3 Support

_______________________________________________
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lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

  reply	other threads:[~2015-01-27 22:35 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-16 12:05 [PATCH] hwmon: (ads7828) Make sample interval configurable Robert Rosengren
2015-01-16 12:05 ` [lm-sensors] " Robert Rosengren
2015-01-16 14:52 ` Guenter Roeck
2015-01-16 14:52   ` [lm-sensors] " Guenter Roeck
2015-01-16 18:30   ` Guenter Roeck
2015-01-16 18:30     ` Guenter Roeck
2015-01-19 11:14     ` SV: " Robert Rosengren
2015-01-19 11:14       ` Robert Rosengren
2015-01-27  7:59     ` Robert Rosengren
2015-01-27  7:59       ` Robert Rosengren
2015-01-27 10:37       ` Jean Delvare
2015-01-27 10:37         ` Jean Delvare
2015-01-27 14:23         ` Guenter Roeck
2015-01-27 14:23           ` Guenter Roeck
2015-01-27 14:07       ` Guenter Roeck
2015-01-27 14:07         ` Guenter Roeck
2015-01-27 19:54         ` Robert Rosengren
2015-01-27 19:54           ` Robert Rosengren
2015-01-27 20:05           ` Guenter Roeck
2015-01-27 20:05             ` Guenter Roeck
2015-01-27 22:34             ` Jean Delvare [this message]
2015-01-27 22:34               ` Jean Delvare
2015-01-28  4:06               ` Guenter Roeck
2015-01-28  4:06                 ` Guenter Roeck
2015-01-27 14:26       ` Guenter Roeck
2015-01-27 14:26         ` Guenter Roeck
2015-01-27 16:37       ` Guenter Roeck
2015-01-27 16:37         ` Guenter Roeck
2015-01-16 20:30 ` Guenter Roeck
2015-01-16 20:30   ` [lm-sensors] " Guenter Roeck
2015-01-28  6:18 ` Robert Rosengren
2015-01-28  6:28   ` Robert Rosengren
2015-01-28  6:28     ` Robert Rosengren
2015-01-28 14:50   ` Guenter Roeck
2015-01-28 14:50     ` Guenter Roeck
2015-01-29  7:00     ` Robert Rosengren
2015-01-29  7:00       ` Robert Rosengren
2015-01-29  7:05       ` Guenter Roeck
2015-01-29  7:05         ` Guenter Roeck
2015-01-29 12:07         ` Robert Rosengren
2015-01-29 12:07           ` Robert Rosengren
2015-01-29 14:10           ` Guenter Roeck
2015-01-29 14:10             ` Guenter Roeck
2015-01-29 19:30           ` Guenter Roeck
2015-01-29 19:30             ` Guenter Roeck
2015-01-31 20:11             ` Guenter Roeck
2015-01-31 20:11               ` Guenter Roeck
2015-02-02  8:12               ` Robert Rosengren
2015-02-02  8:12                 ` Robert Rosengren
2015-02-02 16:21                 ` Guenter Roeck
2015-02-02 16:21                   ` Guenter Roeck

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