From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Lamparter Subject: Re: [PATCH 5/6] arm64: dts: Add ipq6018 SoC and CP01 board support Date: Fri, 14 Jun 2019 22:41:15 +0200 Message-ID: <1981742.H2rzviYcjI@debian64> References: <1559754961-26783-1-git-send-email-sricharan@codeaurora.org> <4056907.DrFocau5Ix@debian64> <1a00e8c8-d07c-3b02-8ea5-6d5f3e2c7b1a@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1a00e8c8-d07c-3b02-8ea5-6d5f3e2c7b1a@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Sricharan R Cc: Rob Herring , Stephen Boyd , Linus Walleij , agross@kernel.org, devicetree , linux-kernel , linux-clk@vger.kernel.org, "open list:GPIO SUBSYSTEM" , linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, linux-arm Mailing List , =?utf-8?B?0J/QsNCy0LXQuw==?= List-Id: devicetree@vger.kernel.org On Wednesday, June 12, 2019 11:48:48 AM CEST Sricharan R wrote: > Hi Christian, > > On 6/10/2019 5:45 PM, Christian Lamparter wrote: > > On Monday, June 10, 2019 12:09:56 PM CEST Sricharan R wrote: > >> Hi Christian, > >> > >> On 6/6/2019 2:11 AM, Christian Lamparter wrote: > >>> On Wed, Jun 5, 2019 at 7:16 PM Sricharan R wrote: > >>>> > >>>> Add initial device tree support for the Qualcomm IPQ6018 SoC and > >>>> CP01 evaluation board. > >>>> > >>>> Signed-off-by: Sricharan R > >>>> Signed-off-by: Abhishek Sahu > >>>> --- /dev/null > >>>> +++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi > >>>> > >>>> + clocks { > >>>> + sleep_clk: sleep_clk { > >>>> + compatible = "fixed-clock"; > >>>> + clock-frequency = <32000>; > >>>> + #clock-cells = <0>; > >>>> + }; > >>>> + > >>> Recently-ish, we ran into an issue with the clock-frequency of the sleep_clk > >>> on older IPQ40XX (and IPQ806x) on the OpenWrt Github and ML. > >>> From what I know, the external "32KHz" crystals have 32768 Hz, but the QSDK > >>> declares them at 32000 Hz. Since you probably have access to the BOM and > >>> datasheets. Can you please confirm what's the real clock frequency for > >>> the IPQ6018. > >>> (And maybe also for the sleep_clk of the IPQ4018 as well?). > >>> > >> > >> What exactly is the issue that you faced ? > >> Looking in to the docs, it is <32000> only on ipq6018 and ipq40xx as well. > > > > We need just a confirmation. > > > > Then again, Currently the qcom-ipq4019.dtsi is using 32768 Hz. > > > > | sleep_clk: sleep_clk { > > | compatible = "fixed-clock"; > > | clock-frequency = <32768>; > > | #clock-cells = <0>; > > | }; > > > > > > > > Which makes sense, because all previous Qualcomm Atheros MIPS and the > > future IPQ8072 SoCs have been either using or deriving a 32768 Hz clock. > > > > For example: The AR9344 derives the clock from the 25MHz/40MHz external > > oscillator. This is explained in "8.16.9 Derived RTC Clock (DERIVED_RTC_CLK)". > > Which mentions that the "32KHz" clock interval is 30.5 usec / 30.48 usec > > depending whenever the external reference crystal has 40MHz or 25MHz. > > (1/30.5usec = 32.7868852 kilohertz!). The QCA9558 datasheet says the same > > in "10.19.11 Derived RTC Clock". > > > > For IPQ8072: I point to the post by Sven Eckelmann on the OpenWrt ML: > > > > "I was only able to verify for IPQ8072 that it had a 32.768 KHz > > sleep clock." > > > > So this is pretty much "why there is an issue", it's confusing. > > Is possible can you please look if there are (fixed) divisors values > > listed in the documentation or the registers and bits that the values > > are stored in? Because then we could just calculate it. > > > > Really sorry for the confusion. So looking little more, SLEEP_CLK is derived > from an external 38.4MHZ crystal, it is 32.768 KHZ. That's really valuable information to have. Thank you! > Somehow the clk freq plan etc seems to mention them only as .032 MHZ and misses > out. That means i will correct the patch for 32768 and probably the > ipq8074.dtsi as well Ok, there's one more issue that Paul found (at least with the IPQ4019), https://patchwork.ozlabs.org/patch/1099482 it seems that the "sleep_clk" node in the qcom-ipq4019.dtsi is not used by the gcc-ipq4019.c clk driver. this causes both wifi rtc_clks and the usb sleep clks to dangle in the /sys/kernel/debug/clk/clk_summary (from a RT-AC58U) clock enable_cnt prepare_cnt rate accuracy phase ---------------------------------------------------------------------------------------- xo 9 9 48000000 0 0 [...] sleep_clk 1 1 32768 0 0 gcc_wcss5g_rtc_clk 1 1 0 0 0 gcc_wcss2g_rtc_clk 1 1 0 0 0 gcc_usb3_sleep_clk 1 1 0 0 0 gcc_usb2_sleep_clk 1 1 0 0 0 with his patch the /sys/kernel/debug/clk/clk_summary looks "better" (something like this:) clock enable_cnt prepare_cnt rate accuracy phase ---------------------------------------------------------------------------------------- xo 9 9 48000000 0 0 [...] gcc_sleep_clk_src 5 5 32000 0 0 gcc_wcss5g_rtc_clk 1 1 32000 0 0 gcc_wcss2g_rtc_clk 1 1 32000 0 0 gcc_usb3_sleep_clk 1 1 32000 0 0 gcc_usb2_sleep_clk 1 1 32000 0 0 but judging from your comment "SLEEP_CLK is derived from an external 38.4MHZ crystal" the gcc_sleep_clk_src / sleep_clk should have xo as the parent. so the ideal output should be: clock enable_cnt prepare_cnt rate accuracy phase ---------------------------------------------------------------------------------------- xo 10 10 48000000 0 0 [...] gcc_sleep_clk 5 5 32768 0 0 gcc_wcss5g_rtc_clk 1 1 32768 0 0 gcc_wcss2g_rtc_clk 1 1 32768 0 0 gcc_usb3_sleep_clk 1 1 32768 0 0 gcc_usb2_sleep_clk 1 1 32768 0 0 or am I missing/skipping over something important? Regards, Christian