Re: [PATCH v4 1/2] arm64: dts: rockchip: add "rockchip, grf" property for RK3399 PMUCRU/CRU

From: Heiko Stuebner <heiko@sntech.de>
To: Xing Zheng <zhengxing@rock-chips.com>
Cc: Doug Anderson <dianders@google.com>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Caesar Wang <wxt@rock-chips.com>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	Brian Norris <briannorris@chromium.org>,
	Jianqun Xu <jay.xu@rock-chips.com>,
	Elaine Zhang <zhangqing@rock-chips.com>,
	David Wu <david.wu@rock-chips.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 1/2] arm64: dts: rockchip: add "rockchip, grf" property for RK3399 PMUCRU/CRU
Date: Wed, 11 Jan 2017 02:12:58 +0100	[thread overview]
Message-ID: <1799437.apf7OqdtKq@phil> (raw)
In-Reply-To: <58758498.40309@rock-chips.com>

Am Mittwoch, 11. Januar 2017, 09:04:24 CET schrieb Xing Zheng:
> Hi Doug,
> 
> On 2017年01月11日 02:45, Doug Anderson wrote:
> > Hi,
> > 
> > On Mon, Jan 9, 2017 at 10:15 PM, Xing Zheng <zhengxing@rock-chips.com> 
wrote:
> >> The structure rockchip_clk_provider needs to refer the GRF regmap
> >> in somewhere, if the CRU node has not "rockchip,grf" property,
> >> calling syscon_regmap_lookup_by_phandle will return an invalid GRF
> >> regmap, and the MUXGRF type clock will be not supported.
> >> 
> >> Therefore, we need to add them.
> >> 
> >> Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
> >> ---
> >> 
> >> Changes in v4:
> >> - separte the binding patch
> >> 
> >> Changes in v3:
> >> - add optional roperty rockchip,grf in rockchip,rk3399-cru.txt
> >> 
> >> Changes in v2:
> >> - referring pmugrf for PMUGRU
> >> - fix the typo "invaild" in COMMIT message
> >> 
> >>   arch/arm64/boot/dts/rockchip/rk3399.dtsi | 2 ++
> >>   1 file changed, 2 insertions(+)
> > 
> > This seems fine to me, so:
> > 
> > Reviewed-by: Douglas Anderson <dianders@chromium.org>
> > 
> > ...but I will say that before you actually add any real "MUXGRF"
> > clocks on rk3399 you _might_ need to rework the code to make things
> > truly "optional".  If it turns out that any existing clocks that
> > already exist today already go through one of these muxes in the GRF
> > and we've always been assuming one setting of the mux, we'll need to
> > make sure we keep assuming that setting of the mux even if the "grf"
> > isn't specified.
> > 
> > As I understand it, your motivation for this patch is to eventually be
> > able to model the EDP reference clock which can either be xin24 or
> > "edp osc".  Presumably the eDP "reference clock" isn't related to any
> > of the pre-existing eDP clocks so that one should be safe.
> 
> Hmm... I had intended to use this patch for EDP reference clock, but we
> don't need to change the parent
> clock (see the BUG: 61664).

Yep that sounds ok. As I said in my replies, we don't support the edp in the 
mainline kernel yet, so nothing old can break here :-)

> I just woud like to add this patch to avoid getting some unavailable
> MUXGRF clock and need to debug it again,
> if we support it one day in future.

could you just check, if we have any other grf-based muxes that we may need in 
the future. Right now I only see pclkin_isp1_wrapper describing such a mux, 
but it would be cool if you could check again.

Thanks
Heiko