On 8/16/2013 7:45 PM, Benoit Cousson wrote: > Hi Gururaja, > > On 16/08/2013 13:36, Hebbar, Gururaja wrote: >> The syntax of compatible property in DT is to mention the Most specific >> match to most generic match. >> >> Since AM335x is the platform with latest IP revision, add it 1st in >> the device id table. > > I don't understand why? The order should not matter at all. Yes, it should not. We are trying to work around a bug in the kernel where the compatible order is not honored (instead the order in of_match[] array matters). There were patches being discussed to fix this. > > I've tried to follow the thread you had with Mark on the v2, but AFAIK, > you've never answered to his latest question. > > Moreover, checking the differences between the Davinci and the am3352 > RTC IP, I would not claim that both are compatible. > > Sure you can use the am3352 with the Davinci driver, but you will lose > the wakeup functionality without even being notify about that. When the kernel is fixed for the bug pointed out above, this should not happen with properly defined compatible property. > > For my point of view, compatible mean that the HW will still be fully > functional with both versions of the driver, which is not the case here. I do not think that's the interpretation of compatible. Its goes from most specific to most generic per the ePAPR spec. That in itself says that 100% functionality is not expected if you don't find a match for the more specific property. > > am3352 DTS must use the ti,am3352-rtc to have the expected behavior. Yes, that's what patch 2/2 does. > Using the ti,da830-rtc version will not make the board working as > expected. So we cannot claim the compatibility. Ideally, the DT file was *always* written as compatible = "ti,am3352-rtc", "ti,da830-rtc"; even when there was no kernel support for AM3352 RTC. That way, there is no need to update the .dts[i] file. As kernel gains functionality, more features (like rtc wake) is available to users. Otherwise they get plain RTC functionality - but at least they get something instead of no RTC. Thanks, Sekhar -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
