Dear Nicolas Ferre, On Tue, 16 Jul 2013 10:46:28 +0200, Nicolas Ferre wrote:
> > Ok, that make sense. I will use compatible names for the capabilities in > > next version. Thanks. > > Hold on a little bit Josh, I know that Jean-Christophe is not in favor > of the use of multiple compatible strings. So, as the code is already > there, let's wait and see if we find another argument... I've asked exactly this question last week at Linaro Connect during the ARM SoC consolidation panel/discussion, where Grant Likely, Arnd Bergmann, Olof and others were answering Device Tree related questions. My question, which precisely had the at91-adc DT binding in mind was precisely whether we should use different compatible properties to identify different revisions of an IP block and let the driver handle those differences, or whether the DT binding should provide sufficient properties (register offsets, bit numbers, etc.) to make the driver independent of the IP revisions. And clearly, the answer was that different compatible properties should be used to identify the different versions of the IP block, and the driver should abstract out the differences. I.e, was has been done for at91-adc is completely the opposite of the best practices for Device Tree on ARM. See http://www.youtube.com/watch?v=zF_AXLgkFy4&feature=player_detailpage#t=1581s where I ask exactly this question, and get answers from Olof Johansson and Grant Likely. They clearly say that the solution of having separate compatible properties and a driver that handles the differences is the way to go. So the way at91-adc (and possibly other at91 drivers) is using the Device Tree is wrong, there should have been multiple compatible properties. It's a shame because this is something we did say when we submitted at91-adc and during the reviews, but the maintainer wasn't listening to our comments... Best regards, Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
