On Thursday 15 January 2015 16:19:19 Laurent Pinchart wrote: > On Thursday 15 January 2015 13:53:22 Wolfram Sang wrote: > > On Thu, Dec 18, 2014 at 02:49:28PM +0200, Laurent Pinchart wrote: > >> On Thursday 18 December 2014 09:21:51 Wolfram Sang wrote: > >>> On Thu, Dec 18, 2014 at 04:15:23AM +0200, Laurent Pinchart wrote: > >>>> The I2C subsystem can match devices without explicit OF support based > >>>> on the part of their compatible property after the comma. However, > >>>> this mechanism uses the first compatible value only. For adxl34x OF > >>>> device nodes the compatible property should list the more specific > >>>> "adi,adxl345" or "adi,adxl346" value first and the "adi,adxl34x" > >>>> fallback value second. This prevents the device node from being > >>>> matched with the adxl34x driver. > >>>> > >>>> Fix this by adding an OF match table with an "adi,adxl34x" compatible > >>>> entry. > >>>> > >>>> Signed-off-by: Laurent Pinchart > >>>> <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> > >>>> --- > >>>> > >>>> drivers/input/misc/adxl34x-i2c.c | 11 +++++++++++ > >>>> 1 file changed, 11 insertions(+) > >>>> > >>>> Another option would have been to add "adxl325" and "adxl326" entries > >>>> to the adxl34x_id I2C match table, but it would have had the drawback > >>>> of requiring a driver update for every new device. > >>> > >>> AFAIK this is even required for compatible entries, to be as specific > >>> as possible. I think this makes sense. With platform_ids, we already > >>> had the problem that pca954x was too generic and was used for both GPIO > >>> extenders and I2C muxers (IIRC). > >> > >> There are three compatible strings defined for the ADXL345 and ADXL346 > >> in Documentation/devicetree/bindings/i2c/trivial-devices.txt: > >> "adi,adxl345", "adi,adxl346", "adi,adxl34x". Given that the last one is > >> a fallback for the first two I don't see a need to add the specific > >> compatible strings to the driver for now. If a new totally incompatible > >> chip named ADXL347 comes out we will need a new driver which won't be > >> allowed to use the "adi,adxl34x" compatible string. > > > > Been there, got bitten. We only found out too late, because one driver > > was in i2c and the other in GPIO (or LED even?), both using "953x" :( > > That seems like a development, review and/or merge process failure to me, I > wouldn't avoid generic compatible strings for that reason only. > > > > An option would be to remove "adi,adxl34x" from > > > Documentation/devicetree/bindings/i2c/trivial-devices.txt, in which case > > > the driver should match explicitly on "adi,adxl345" and "adi,adxl346". > > > That might clash with the DT ABI stability requirements though. > > > > I do prefer this: > > > > 1) add specific compatible values to the driver. We do those updates for > > new devices all the time > > Do you mean OF compatible values, or I2C match table entries ? I assume OF > compatible values. > > As the ADXL346 is backward-compatible with the ADXL345, and as the driver > doesn't support the ADXL346-specific features, how about adding only the > adxl345 for now, and using compatible = "adi,adxl346", "adi,adxl345"; for > the ADXL346 ? I spoke too fast. The driver supports ADXL346-specific features, but does so by detecting the device model at runtime. I still believe it would make sense to list both the 346 and 345 models in DT for 346 devices, as they're compatible with the 345. > > 2) also add "34x" as a compatible but mark it as deprecateed > > 3) delete "34x" from trivial devices > > OK. > > > Everyone OK with that? -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
