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Message-ID: <20141023162754.GA21343@roeck-us.net> Date: Thu, 23 Oct 2014 09:27:55 -0700 From: Guenter Roeck <linux@...ck-us.net> To: Andrew Lunn <andrew@...n.ch> Cc: Florian Fainelli <f.fainelli@...il.com>, netdev <netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 06/14] net: dsa: Add support for hardware monitoring On Thu, Oct 23, 2014 at 03:47:06PM +0200, Andrew Lunn wrote: > > >>+static DEVICE_ATTR_RO(temp1_input); > > > > > >You probably want the number of temperature sensors to come from the > > >switch driver, and support arbitrary number of temperature sensors? > > > > In that case we would need the number of sensors, pass a sensor index, > > and create a dynamic number of attributes. The code would get much more > > complex without real benefit unless there is such a chip > > We are two different use cases here: > > One switch chip with multiple temperature sensors I understand this case. However, quite frankly, I consider this quite unlikely to happen. > Multiple switch chips, each with its own temperature sensor. > I don't really see the problem. My understanding is that each of those switch chips will instantiate itself, dsa_switch_setup will be called, which will create a new hwmon device with its own sensors. That is how all other hwmon devices do it, and it works just fine. Why would that approach not work for switches in the dsa infrastructure ? Am I missing something ? If the concern or assumption is that there can not be more than one "temp1_input" attribute, here is an example from a system with a large number of chips with temperature sensors. root@...-xb49:/sys/class/hwmon# ls hwmon*/temp1_input hwmon1/temp1_input hwmon22/temp1_input hwmon35/temp1_input hwmon10/temp1_input hwmon23/temp1_input hwmon36/temp1_input hwmon11/temp1_input hwmon24/temp1_input hwmon37/temp1_input hwmon12/temp1_input hwmon25/temp1_input hwmon38/temp1_input hwmon13/temp1_input hwmon26/temp1_input hwmon39/temp1_input hwmon14/temp1_input hwmon27/temp1_input hwmon4/temp1_input hwmon15/temp1_input hwmon28/temp1_input hwmon40/temp1_input hwmon16/temp1_input hwmon29/temp1_input hwmon5/temp1_input hwmon17/temp1_input hwmon3/temp1_input hwmon6/temp1_input hwmon18/temp1_input hwmon30/temp1_input hwmon7/temp1_input hwmon19/temp1_input hwmon31/temp1_input hwmon8/temp1_input hwmon2/temp1_input hwmon32/temp1_input hwmon9/temp1_input hwmon20/temp1_input hwmon33/temp1_input hwmon21/temp1_input hwmon34/temp1_input There are 6xDS1625, 11xDS1721, 1xLM95234, 4xMAX6697, and 17xLTC2978 in this system if I counted correctly. That doesn't mean that the drivers need to do anything special for their multiple instances. Also, the "name" of each instance does not have to be unique. The "name" reflects the driver name, not its instance. root@...-xb49:/sys/class/hwmon# grep . */name | grep max hwmon20/name:max6697 hwmon21/name:max6697 hwmon22/name:max6697 hwmon23/name:max6697 > I don't know of any hardware using either of these uses cases, but > they could appear in the future. > > If we are not doing the generic implementation now, how about avoiding > an ABI break in the future, by hard coding the sensors with .0.0 on > the end? I am a little lost. What would that be for, and what would the ABI breakage be ? Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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