<br><br><div class="gmail_quote">On Tue, Jun 18, 2013 at 5:07 PM, Kishon Vijay Abraham I <span dir="ltr"><<a href="mailto:kishon@ti.com" target="_blank">kishon@ti.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Hi,<br> <div><div class="h5"><br> On Tuesday 18 June 2013 03:33 PM, Rahul Sharma wrote:<br> > Thanks all,<br> ><br> > On Fri, Jun 14, 2013 at 11:39 AM, 김승우 <<a href="mailto:sw0312.kim@samsung.com">sw0312.kim@samsung.com</a>> wrote:<br> >> Hello Kishon,<br> >><br> >> On 2013년 06월 13일 21:54, Kishon Vijay Abraham I wrote:<br> >>> Hi,<br> >>><br> >>> On Thursday 13 June 2013 04:51 PM, Inki Dae wrote:<br> >>>><br> >>>><br> >>>>> -----Original Message-----<br> >>>>> From: Sylwester Nawrocki [mailto:<a href="mailto:s.nawrocki@samsung.com">s.nawrocki@samsung.com</a>]<br> >>>>> Sent: Thursday, June 13, 2013 5:56 PM<br> >>>>> To: Rahul Sharma<br> >>>>> Cc: Rahul Sharma; Inki Dae; <a href="mailto:linux-samsung-soc@vger.kernel.org">linux-samsung-soc@vger.kernel.org</a>;<br> >>>>> devicetree-<br> >>>>> <a href="mailto:discuss@lists.ozlabs.org">discuss@lists.ozlabs.org</a>; DRI mailing list; Kukjin Kim; Seung-Woo Kim;<br> >>>>> Sean Paul; sunil joshi; Kishon Vijay Abraham I; Stephen Warren;<br> >>>>> <a href="mailto:grant.likely@linaro.org">grant.likely@linaro.org</a><br> >>>>> Subject: Re: [RFC 0/2] exynos5250/hdmi: replace dummy hdmiphy clock with<br> >>>>> pmu reg control<br> >>>>><br> >>>>> Hi,<br> >>>>><br> >>>>> On 06/13/2013 06:26 AM, Rahul Sharma wrote:<br> >>>>>> Mr. Dae,<br> >>>>>><br> >>>>>> Thanks for your valuable inputs.<br> >>>>>><br> >>>>>> I posted it as RFC because, I also have received comments to register<br> >>>>>> hdmiphy as a clock controller. As we always configure it for specific<br> >>>>>> frequency, hdmi-phy looks similar to a PLL. But it really doesn't<br> >>>>>> belong to that class. Secondly prior to exynos5420, it was a i2c<br> >>>>>> device. I am not sure we can register a I2C device as a clock<br> >>>>>> controller. I wanted to discuss and explore this option here.<br> >>>>><br> >>>>> Have you considered using the generic PHY framework for those HDMI<br> >>>>> PHY devices [1] ? I guess we could add a dedicated group of ops for<br> >>>>> video PHYs, similarly as is is done with struct v4l2_subdev_ops. For<br> >>>>> configuring things like the carrier/pixel clock frequency or anything<br> >>>>> what's common across the video PHYs.<br> >>>>><br> >>>>> Perhaps you could have a look and see if this framework would be<br> >>>>> useful for HDMI and possibly point out anything what might be missing ?<br> >>>>><br> >>>>> I'm not sure it it really solves the issues specific to the Exynos<br> >>>>> HDMI but at least with a generic PHY driver the PHY module would be<br> >>>>> separate from the PHY controller, as often same HDMI DPHY can be used<br> >>>>> with various types of a HDMI controller. So this would allow to not<br> >>>>> duplicate the HDMI PHY drivers in the long-term perspective.<br> >>>><br> >>>> Yeah, at least, it seems that we could use PHY module to control PMU<br> >>>> register, HDMI_PHY_CONTROL. However, PHY module provides only init/on/off<br> >>>> callbacks. As you may know, HDMIPHY needs i2c interfaces to control<br> >>>> HDMIPHY<br> >>>> clock. So with PHY module, HDMIPHY driver could enable PMU more<br> >>>> generically,<br> >>>> but also has to use existing i2c stuff to control HDMIPHY clock. I had a<br> >>>> quick review to Generic PHY Framework[v6] but I didn't see that the PHY<br> >>>> module could generically support more features such as i2c stuff.<br> >>><br> >>> I don't think PHY framework needs to provide i2c interfaces to program<br> >>> certain configurations. Instead in one of the callbacks (init/on/off)<br> >>> PHY driver can program whatever it wants using any of the interfaces it<br> >>> needs. IMO PHY framework should work independent of the interfaces.<br> >><br> >> In exnoys hdmi case, i2c interface is not the exact issue. In exynos<br> >> hdmi, hdmiphy should send i2c configuration about video clock<br> >> information as the video mode information including resolution, bit per<br> >> pixel, refresh rate passed from drm subsystem. So init/on/off callbacks<br> >> of phy framework are not enough for exynos hdmiphy and it should have a<br> >> callback to set video mode.<br> >><br> >> Do you have plan to add driver specific extend callback pointers to phy<br> >> framework?<br> >><br> >> Currently, hdmi directly calls phy operations, but Rahul's another patch<br> >> set, mentioned by Inki, divides hdmi and hdmiphy and hdmi and hdmiphy is<br> >> connected with exynos hdmi own sub driver callback operations.<br> >><br> >> IMHO, if phy framework can support extend callback feature, then this<br> >> own sub driver callbacks can be replaced with phy framework at long term<br> >> view.<br> ><br> > Extended callbacks are always welcome. I can also use phy device<br> > private data to pass on private ops like get_pixelclk and set_pixelclk.<br> <br> </div></div>I would recommend creating a wrapper to the existing PHY framework<br> for HDMI PHY. That way, we can have other HDMI phys added<br> easily. We need to figure out all the ops that might be needed by the<br> HDMI PHY to be added to the wrapper.<br> IMO extended callbacks can lead to abuse of the system and should be<br> used only when absolutely necessary.<br> <br> Thanks<br> <span class="HOEnZb"><font color="#888888">Kishon<br> </font></span></blockquote></div><br><div>Thanks Kishon,</div><div><br></div><div>I have started working on this wrapper layer which is customized for video phys.</div><div>As if now, adding set_dv_timing, get_dv_timing as the only additional callbacks.</div> <div>I will post the RFC patches.</div><div><br></div><div>regards,</div><div>Rahul Sharma.</div><div><br></div>