On Mon, May 30, 2011 at 08:57:45PM +0400, Anton Vorontsov wrote: > On Mon, May 30, 2011 at 02:29:58PM +0000, Tabi Timur-B04825 wrote: > > On Mon, May 30, 2011 at 3:24 AM, Wolfram Sang <w.s...@pengutronix.de> wrote: > > > > > The first place where this should be mentioned is the datasheet of the > > > pt-chip, so you might ask the producer to add this information (don't > > > expect much to happen, though). > > > > It's true that the data sheet does not mention that it's identical to > > the DS1307, but that's still no excuse for not noticing it and writing > > a whole driver for it. :-( > > > > > IIRC I asked you explicitly for the differences between the chips. If > > > there are none, you can use the driver directly, right? :) > > > > Yes. The device tree node for the PT7C4338 device should just say > > > > /* The board has a PT7C4338, which is compatible with the DS1307 */ > > compatible = "dallas,ds1307"; > > While it seems to be 100% compatible, there could be chip-specific > bugs or some interesting features that are hidden behind "reserved" > bits and registers. > > So I think device tree should not lie about the chip model. Doing > 'compatible = "pericom,pt7c4338", "dallas,ds1307"' is perfectly fine.
Correct. It's fine (and encouraged) to claim compatibility, but the node should always specify the exact part in the compatible list. > > Note that today the several compatible entries approach gives you > almost nothing, as you will need to add pt7c4338 entry into the driver > anyway. > > I tried to improve this, i.e. make linux do OF-matching on the most > generic compatible entry (the last one): > > http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg21196.html > > It was received coldly though: > > http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg22041.html > http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg21273.html On that note, device-tree-style of_match_table binding now works for i2c devices, so the problems you were having with that thread should now be solved. The of_find_i2c_driver() approach was only ever a heuristic to get things working in the short term. of_match_table is is better in the long run. g. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
