[Skiboot] [RFC PATCH 0/3] hwmon: (ibmpowernv) add DTS support
Cedric Le Goater
clg at fr.ibm.com
Sat Feb 21 18:14:25 AEDT 2015
On 02/21/2015 12:52 AM, Guenter Roeck wrote:
> On 02/20/2015 12:15 PM, Cedric Le Goater wrote:
>> On 02/20/2015 05:52 PM, Guenter Roeck wrote:
>>> On Fri, Feb 20, 2015 at 04:07:34PM +0100, Cédric Le Goater wrote:
>>>> Hello !
>>>> These patches rework the ibmpowernv driver to support the new device
>>>> tree as proposed by this patchset on the skiboot mailing list :
>>>> They are based on Linux 3.19 and were tested on IBM Power and Open Power
>>>> systems running trusty.
>>>> The main issue is that the new device tree is incompatible with the
>>>> previous ibmpowernv drivers. The consequence is no powernv sensors
>>>> on systems with such a opal/linux configuration.
>>> I don't think that would be acceptable. There must be lots of such
>>> systems out there. Why does it have to be incompatible ?
>>> Can't it support both the old and new versions ?
>> I should have provided more explanation in the Linux patchset. Sorry
>> for that. Here is the rationale behind this brutal code change.
>> The initial ibmpowernv driver was designed in the early days of the
>> powernv platform and the device tree it is using to expose the sensors
>> has some limitations that makes it difficult to add new ones. The current
>> layout of the device tree is also tightly coupled to IBM Power systems
>> and their service processor (FSP). Open Power systems are different and
>> need a different solution.
>> It is to get more sensors out the P8 (and there are quite a few) that
>> the OPAL patchset  proposes a new device tree. On the Linux side, it
>> feels simpler to make a jump forward and break the compatibility than
>> to maintain multiple branches of code just to keep alive an early v1
>> of the ibmpowernv driver.
> Would it possibly be appropriate to write a different driver for the new
> device tree ?
Sure. That is an option.
There are no conflicts between the trees so we can live with two drivers
using the same sensors/ root node. With time we will deprecate the initial
Is that the preferred option ? How would we name the new driver ?
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