From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xing Zheng Subject: Re: [RESEND PATCH v1 4/4] clk: rockchip: rk3036: fix and add node id for emac clock Date: Wed, 06 Jan 2016 21:05:56 +0800 Message-ID: <568D1134.9010305@rock-chips.com> References: <1451293433-32392-1-git-send-email-zhengxing@rock-chips.com> <5681E8E4.2010303@rock-chips.com> <5681F121.3070307@rock-chips.com> <1562268.fb58QJ4jV7@diego> <01110793-A349-4006-82A2-4489CE832B19@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <01110793-A349-4006-82A2-4489CE832B19@rock-chips.com> Sender: linux-clk-owner@vger.kernel.org To: =?GB2312?B?SGVpa28gU3SouWJuZXI=?= Cc: Yakir Yang , Mark Rutland , devicetree@vger.kernel.org, Pawel Moll , Ian Campbell , Michael Turquette , Kumar Gala , Stephen Boyd , linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, Rob Herring , linux-arm-kernel@lists.infradead.org, keescook@google.com, linux-clk@vger.kernel.org, leozwang@google.com, xing.zheng@rock-chips.com List-Id: linux-rockchip.vger.kernel.org Hi Heiko, On 2016=C4=EA01=D4=C202=C8=D5 10:34, Xing Zheng wrote: > Hi Heiko, > Thank you for your patch, I will apply and test it later. > > Thanks. > >> =D4=DA 2016=C4=EA1=D4=C22=C8=D5=A3=AC06:10=A3=ACHeiko St=A8=B9bner <= heiko@sntech.de> =D0=B4=B5=C0=A3=BA >> >> Hi Xing, >> >> Am Dienstag, 29. Dezember 2015, 10:34:09 schrieb Xing Zheng: >>> On 2015=C4=EA12=D4=C229=C8=D5 09:59, Yakir Yang wrote: >>>> On 12/28/2015 08:41 PM, Heiko St=A8=B9bner wrote: >>>>> Am Montag, 28. Dezember 2015, 17:03:53 schrieb Xing Zheng: >>>>>> Due to referred old version TRM, there is incorrect emac clock n= ode, >>>>>> we should fix it. The SEL_21_9 is the parent of SEL_21_4. >>>>>> >>>>>> In the emac driver, we need to refer HCLK_MAC, and because There= are >>>>>> only 3PLLs (APLL/GPLL/DPLL) on the rk3036, most clock are under = the >>>>>> GPLL, and it is unable to provide the accurate rate for mac_ref = which >>>>>> need to 50MHz probability, we should let it under the APLL and a= re >>>>>> able to set the freq which integer multiples of 50MHz, so we add= these >>>>>> emac node for reference. >>>>> I don't really follow here. While I do understand that the emac n= eeds >>>>> 50MHz, I >>>>> don't think using the APLL as source is helpful. >>>>> >>>>> The APLL is the main clocksource for the cpu-cores, including fre= quency >>>>> scaling, and while it currently only lists 816MHz as sole frequen= cy, >>>>> you're >>>>> pretty much guaranteed to not get your correct multiple of 50MHz = from >>>>> there >>>>> either. And limiting the cpu to just do 600MHz to get the mac wor= king >>>>> sounds >>>>> pretty bad ;-) . >>>>> >>>>> >>>>> In the rk3036 cru-node the gpll gets set to 594MHz. Is there a >>>>> special reason >>>>> why it needs to be 594MHz and cannot be a round 600MHz? Because t= hat >>>>> would >>>>> also provide your 50MHz-multiple nicely. >>>> Yes, this magic 594MHz would help to support the standard HDMI >>>> resolutions, here are the math: >>>> >>>> 1920x1080-60Hz DCLK =3D 148.5MHz =3D 594MHz / 4 >>>> 1280x720-60Hz DCLK =3D 74.25MHz =3D 594MHz / 8 >>>> 720x480-60Hz DCLK =3D 27MHz =3D 594MHz / 22 >>>> >>>> Thanks, >>>> - Yakir >>> Thanks Yakir. >>> >>> Hi Heiko, >>> From the above, do you have better idea for the RK3036's emac witho= ut >>> ext-oscillator? >> During the last days I did play a bit with the clock framework. As I= don't=20 >> have a Kylin (or any rk3036) board, I did build a test-case with pcl= k_cpu on=20 >> the rk3188 (which can be affected by the armclk if not reparented to= the=20 >> gpll), which got sucessfully adapted to get back to (or near) the or= iginally=20 >> requested frequency. >> >> So ideally you could roll back your mux/div split here and try the a= ttached=20 >> diff. In theory it should help :-) . >> As can be seen by the FIXMEs, not fully finished, but I'd like to de= termine if=20 >> it fixes the issue at least. >> >> >> Heiko >> I tested your patch just now, it seems to work well. I will do more tes= ts. Thank you. :-)