On 20.11.2017 08:54, Daniel Vetter wrote: > On Tue, Nov 14, 2017 at 03:34:19PM +0100, Andrzej Hajda wrote: >> On 05.04.2017 14:04, Thierry Reding wrote: >>> On Wed, Apr 05, 2017 at 10:52:32AM +0200, Lucas Stach wrote: >>>> Hi Rob, >>>> >>>> Am Mittwoch, den 29.03.2017, 08:56 -0500 schrieb Rob Herring: >>>>> On Mon, Jan 23, 2017 at 10:33 AM, Thierry Reding >>>>> <thierry.reding@xxxxxxxxx> wrote: >>>>>> On Fri, Jan 13, 2017 at 06:36:30PM +0100, Lucas Stach wrote: >>>>>>> The i2c adapter on DP AUX is purely a software construct. Linking >>>>>>> it to the device node of the parent device is wrong, as it leads to >>>>>>> 2 devices sharing the same device node, which is bad practice, as >>>>>> Who says that two devices can't share the same device node? It's done >>>>>> all the time. >>>>> It's done *some of the time* and I would not consider it best practice. >>>>> >>>>>>> well as the i2c trying to populate children of the i2c adapter by >>>>>>> looking at the child device nodes of the parent device. >>>>>> A set of patches landed in v4.9 to work around this issue in a better >>>>>> way. See: >>>>>> >>>>>> 98b00488459e dt-bindings: i2c: Add support for 'i2c-bus' subnode >>>>>> 7e4c224abfe8 i2c: core: Add support for 'i2c-bus' subnode >>>>> What does this buy us? I don't see why this needs to be in DT either. >>>>> Contrary to popular belief, DT is not the only way to instantiate >>>>> devices, C code can still do it. >>>>> >>>>> Also, if this one line removal has no side effects, then how was it >>>>> even needed? We can always add it back if there's some argument for >>>>> why it is needed. >>>> Okay, so I take this as you mostly agreeing with the rationale of this >>>> patch. >>> For some general background on this: I was originally using this for DP >>> support on Tegra (though that ended up never getting merged because of a >>> particularily frustrating episode of trying to get better link training >>> support into the core helpers) and use it as a means to obtain the I2C >>> controller used for DDC. On Tegra, and I suspect other devices as well, >>> the DP AUX controller is separate from the encoder, so the idea was to >>> link them together using a standard ddc-i2c-bus phandle. >>> >>> I ended up not needing that because the encoder and DP AUX controller >>> are so tightly linked on Tegra that I need direct access to the DP AUX >>> anyway and can therefore directly get the I2C controller from that. >>> >>> If there aren't any other users of this, I suppose we could simply >>> remove the line. Should someone turn up in the future and require the >>> I2C controller to be looked up from a phandle we could add it again, >>> at which point we'd have to investigate again how to get rid of the >>> errors. >>> >>> Acked-by: Thierry Reding <treding@xxxxxxxxxx> >> It looks like the patch has been accepted but not merged. Who can pick >> it up? or is it OK if I put it int drm-misc? > I don't have the patch itself, but sounds good. Just go ahead and push. > -Daniel OK, done. Regards Andrzej _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
