Re: [PATCH v2 4/8] drm: rockchip/dp: add rockchip platform dp driver

[Yakir Yang]

Hi Thierry,

å 2015/8/10 21:17, Thierry Reding åé:
> On Mon, Aug 10, 2015 at 08:59:44PM +0800, Yakir Yang wrote:
> > Hi Thierry,
> >
> > å 2015/8/10 18:00, Thierry Reding åé:
> > > On Sat, Aug 08, 2015 at 11:54:38AM +0800, Yakir Yang wrote:
> > > [...]
> > > >          edp: edp@ff970000 {
> > > [...]
> > > >                  hsync-active-high = <0>;
> > > >                  vsync-active-high = <0>;
> > > >                  interlaced = <0>;
> > > These look like they should come from the display mode definition (EDID)
> > > rather than device tree.
> > I do think so, those numbers can parse from struct drm_mode. But I haven't
> > send those changes yet, cause I want to merge the split analogix_dp first,
> > and
> > then send some patches to improve it. If you think it's better to imptoved
> > those
> > now, I would like to do it , please let me know ;)
> >
> > > >                  samsung,color-space = <0>;
> > > >                  samsung,dynamic-range = <0>;
> > > >                  samsung,ycbcr-coeff = <0>;
> > > I think these should also come from EDID, though I'm not sure if we
> > > store this in internal data structures yet.
> > Same to previous reply
> >
> > > >                  samsung,color-depth = <1>;
> > > This is probably drm_display_info.bpc.
> > Same to previous reply
> >
> > > >                  samsung,link-rate = <0x0a>;
> > > >                  samsung,lane-count = <1>;
> > > And these should really be derived from values in the DPCD and adjusted
> > > (if necessary) during link training.
> > >
> > > Why would you ever want to hard-code the above?
> > Yes, I do meet the problem that my eDP screen need lane-count to 4, but my
> > DP TV need lane-count to 1. Just like previous reply, if you think I should
> > improved
> > them in this series, I would rather to do it.
> The problem with these is that if you keep them in for your initial
> submission, you can never (or only under extreme pain) remove them.
> Anything in DTB needs to be effectively supported forever.
>
> Also since these don't make sense to hard-code, just improve the code
> and get rid of the need for these DT properties. Mind you that you still
> need to keep the code to parse them, because presumably Exynos relies on
> them. But depending on how you split up the driver you might be able to
> restrict these compatibility hacks to Exynos and not carry them forward
> into your new driver.

Okay, thanks for your remind ;)

> > > > > > +	dp->clk_24m = devm_clk_get(dev, "clk_dp_24m");
> > > > > Same here, maybe "dp_24m".
> > > > Like my previous reply. And actually as those two clocks all have
> > > > a common prefix "SCLK" in rk3288 clock tree, I thinkt we can name
> > > > them to "sclk_dp" & "sclk_dp_24m", is it okay ?
> > > I don't think there's a need for these common prefixes. The names here
> > > are identifiers in the context of the IP block, so any SoC-specific
> > > prefixes are irrelevant. Also they do appear, in DT and in code, in the
> > > context of clocks already, so "sclk_" or "clk_" is completely redundant
> > > in these names.
> > The sclk_dp & sclk_dp_24m is not IP common ask, it's only exist in RK3288
> > SoC (Like exynos
> > only got one "dp" clock), and actually I add this to rockchip platform dp
> > driver not analogix
> > dp driver. So I think it's okay to add some platform some common prefixes.
> >
> > And I got a better idea for those clock. "sclk_dp" & "sclk_dp_24m" is
> > provided for the eDP phy,
> > and I just take Heiko suggest that add an new phy-rockchip-dp.c driver, so
> > it's better to move
> > those clock to phy driver, and rename them to "dp-phy" && "dp-phy-24m".
> I agree that dealing with these in a PHY driver sounds like the better
> option. However, I still think that the dp-phy prefix is redundant. The
> names are in a per-driver scope, so "dp-phy" is implied by the device
> tree binding and driver already. You could simply use shorter names such
> as "phy" and "24m" for example.
>
> Also note that the clock provider will already have the proper names for
> these, so the clock tree will end up showing the provider names. The
> names in the binding are merely the "consumer" names.

Agree, thanks

- Yakir
> Thierry


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