Hi, On Tuesday 30 July 2013 09:12 AM, Rahul Sharma wrote: > > > On Tue, Jun 18, 2013 at 5:07 PM, Kishon Vijay Abraham I <kishon@xxxxxx > <mailto:kishon@xxxxxx>> wrote: > > Hi, > > On Tuesday 18 June 2013 03:33 PM, Rahul Sharma wrote: > > Thanks all, > > > > On Fri, Jun 14, 2013 at 11:39 AM, 김승우 <sw0312.kim@xxxxxxxxxxx > <mailto:sw0312.kim@xxxxxxxxxxx>> wrote: > >> Hello Kishon, > >> > >> On 2013년 06월 13일 21:54, Kishon Vijay Abraham I wrote: > >>> Hi, > >>> > >>> On Thursday 13 June 2013 04:51 PM, Inki Dae wrote: > >>>> > >>>> > >>>>> -----Original Message----- > >>>>> From: Sylwester Nawrocki [mailto:s.nawrocki@xxxxxxxxxxx > <mailto:s.nawrocki@xxxxxxxxxxx>] > >>>>> Sent: Thursday, June 13, 2013 5:56 PM > >>>>> To: Rahul Sharma > >>>>> Cc: Rahul Sharma; Inki Dae; linux-samsung-soc@xxxxxxxxxxxxxxx > <mailto:linux-samsung-soc@xxxxxxxxxxxxxxx>; > >>>>> devicetree- > >>>>> discuss@xxxxxxxxxxxxxxxx <mailto:discuss@xxxxxxxxxxxxxxxx>; DRI > mailing list; Kukjin Kim; Seung-Woo Kim; > >>>>> Sean Paul; sunil joshi; Kishon Vijay Abraham I; Stephen Warren; > >>>>> grant.likely@xxxxxxxxxx <mailto:grant.likely@xxxxxxxxxx> > >>>>> Subject: Re: [RFC 0/2] exynos5250/hdmi: replace dummy hdmiphy clock with > >>>>> pmu reg control > >>>>> > >>>>> Hi, > >>>>> > >>>>> On 06/13/2013 06:26 AM, Rahul Sharma wrote: > >>>>>> Mr. Dae, > >>>>>> > >>>>>> Thanks for your valuable inputs. > >>>>>> > >>>>>> I posted it as RFC because, I also have received comments to register > >>>>>> hdmiphy as a clock controller. As we always configure it for specific > >>>>>> frequency, hdmi-phy looks similar to a PLL. But it really doesn't > >>>>>> belong to that class. Secondly prior to exynos5420, it was a i2c > >>>>>> device. I am not sure we can register a I2C device as a clock > >>>>>> controller. I wanted to discuss and explore this option here. > >>>>> > >>>>> Have you considered using the generic PHY framework for those HDMI > >>>>> PHY devices [1] ? I guess we could add a dedicated group of ops for > >>>>> video PHYs, similarly as is is done with struct v4l2_subdev_ops. For > >>>>> configuring things like the carrier/pixel clock frequency or anything > >>>>> what's common across the video PHYs. > >>>>> > >>>>> Perhaps you could have a look and see if this framework would be > >>>>> useful for HDMI and possibly point out anything what might be missing ? > >>>>> > >>>>> I'm not sure it it really solves the issues specific to the Exynos > >>>>> HDMI but at least with a generic PHY driver the PHY module would be > >>>>> separate from the PHY controller, as often same HDMI DPHY can be used > >>>>> with various types of a HDMI controller. So this would allow to not > >>>>> duplicate the HDMI PHY drivers in the long-term perspective. > >>>> > >>>> Yeah, at least, it seems that we could use PHY module to control PMU > >>>> register, HDMI_PHY_CONTROL. However, PHY module provides only init/on/off > >>>> callbacks. As you may know, HDMIPHY needs i2c interfaces to control > >>>> HDMIPHY > >>>> clock. So with PHY module, HDMIPHY driver could enable PMU more > >>>> generically, > >>>> but also has to use existing i2c stuff to control HDMIPHY clock. I had a > >>>> quick review to Generic PHY Framework[v6] but I didn't see that the PHY > >>>> module could generically support more features such as i2c stuff. > >>> > >>> I don't think PHY framework needs to provide i2c interfaces to program > >>> certain configurations. Instead in one of the callbacks (init/on/off) > >>> PHY driver can program whatever it wants using any of the interfaces it > >>> needs. IMO PHY framework should work independent of the interfaces. > >> > >> In exnoys hdmi case, i2c interface is not the exact issue. In exynos > >> hdmi, hdmiphy should send i2c configuration about video clock > >> information as the video mode information including resolution, bit per > >> pixel, refresh rate passed from drm subsystem. So init/on/off callbacks > >> of phy framework are not enough for exynos hdmiphy and it should have a > >> callback to set video mode. > >> > >> Do you have plan to add driver specific extend callback pointers to phy > >> framework? > >> > >> Currently, hdmi directly calls phy operations, but Rahul's another patch > >> set, mentioned by Inki, divides hdmi and hdmiphy and hdmi and hdmiphy is > >> connected with exynos hdmi own sub driver callback operations. > >> > >> IMHO, if phy framework can support extend callback feature, then this > >> own sub driver callbacks can be replaced with phy framework at long term > >> view. > > > > Extended callbacks are always welcome. I can also use phy device > > private data to pass on private ops like get_pixelclk and set_pixelclk. > > I would recommend creating a wrapper to the existing PHY framework > for HDMI PHY. That way, we can have other HDMI phys added > easily. We need to figure out all the ops that might be needed by the > HDMI PHY to be added to the wrapper. > IMO extended callbacks can lead to abuse of the system and should be > used only when absolutely necessary. > > Thanks > Kishon > > > Thanks Kishon, > > I have started working on this wrapper layer which is customized for video phys. > As if now, adding set_dv_timing, get_dv_timing as the only additional callbacks. > I will post the RFC patches. Idea of creating wrapper layer for different types of controller is shot down in the community [1] :-s [1] -> http://lists.infradead.org/pipermail/linux-arm-kernel/2013-July/181710.html Thanks Kishon -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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