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<707c4679-fde6-1714-ced0-dcf7ca8380a9@nvidia.com> <055457fd-621b-6c93-b671-d5e5380698c6@nvidia.com> <20190717071105.3750a021@dimatab> <77df234f-aa40-0319-a593-f1f19f0f1c2a@nvidia.com> <20190717084221.2e9af56c@dimatab> <093462f3-8c6d-d084-9822-ae4eff041c64@nvidia.com> <20190717093317.70fefb27@dimatab> <6e73dcee-6e24-b646-97a4-4b34aedd231d@nvidia.com> <16f8b146-2581-a842-4997-53ab05b62c70@gmail.com> <71272e9a-0f2a-c20d-6532-7e9057ad985c@gmail.com> <78fd19b9-b652-8ac3-1f57-3b4adadee03f@nvidia.com> <351a07d4-ba90-4793-129b-b1a733f95531@nvidia.com> <9271ae75-5663-e26e-df26-57cba94dab75@nvidia.com> <7ae3df9a-c0e9-cf71-8e90-4284db8df82f@nvidia.com> From: Sowjanya Komatineni Message-ID: <46b55527-da5d-c0b7-1c14-43b5c6d49dfa@nvidia.com> Date: Wed, 17 Jul 2019 14:51:52 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1563400314; bh=kBQ0bRsmIjyjQswwWUPwjlwqGKPH7VtwuC0XfRb6HB8=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=lN6wjw+eSUSPnrxJW8ANu7hSGOGrxtrpzVTwEKULttibrPyC35pp8OpGgaYdPbJQp 4U5F085+F8U1iQPk5siOWVsMH37RwHr8+0k80N0I/pYSu7MrwCoglUMbHpKPII0g2X RE7KOfKlWifR32ZBMPic9SPEjTi7A58KKAYj/3kVbZ6TQF4h2eWnqnLwPEkQGX1XfQ CQJ+DIsNQCgtLVcpnlRZ9q6L5PIU0oXL1sKIEbUCFQIvh8/pytUPy39Zop3kzC+eXj hYU1F20ky1uyab6c5f62NAVfUTwWzaa/wF8FIxmBvFx+LuT/+I3c+s+/mzxAHOpNOz SyDhHk0cz6UlA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/17/19 2:30 PM, Dmitry Osipenko wrote: > 17.07.2019 23:11, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 7/17/19 1:01 PM, Sowjanya Komatineni wrote: >>> On 7/17/19 12:43 PM, Dmitry Osipenko wrote: >>>> 17.07.2019 21:54, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>>> On 7/17/19 11:51 AM, Sowjanya Komatineni wrote: >>>>>> On 7/17/19 11:32 AM, Dmitry Osipenko wrote: >>>>>>> 17.07.2019 20:29, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1= =82: >>>>>>>> On 7/17/19 8:17 AM, Dmitry Osipenko wrote: >>>>>>>>> 17.07.2019 9:36, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1= =82: >>>>>>>>>> On 7/16/19 11:33 PM, Dmitry Osipenko wrote: >>>>>>>>>>> =D0=92 Tue, 16 Jul 2019 22:55:52 -0700 >>>>>>>>>>> Sowjanya Komatineni =D0=BF=D0=B8=D1=88= =D0=B5=D1=82: >>>>>>>>>>> >>>>>>>>>>>> On 7/16/19 10:42 PM, Dmitry Osipenko wrote: >>>>>>>>>>>>> =D0=92 Tue, 16 Jul 2019 22:25:25 -0700 >>>>>>>>>>>>> Sowjanya Komatineni =D0=BF=D0=B8=D1= =88=D0=B5=D1=82: >>>>>>>>>>>>>> On 7/16/19 9:11 PM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>> =D0=92 Tue, 16 Jul 2019 19:35:49 -0700 >>>>>>>>>>>>>>> Sowjanya Komatineni =D0=BF=D0=B8= =D1=88=D0=B5=D1=82: >>>>>>>>>>>>>>>> On 7/16/19 7:18 PM, Sowjanya Komatineni wrote: >>>>>>>>>>>>>>>>> On 7/16/19 3:06 PM, Sowjanya Komatineni wrote: >>>>>>>>>>>>>>>>>> On 7/16/19 3:00 PM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>> 17.07.2019 0:35, Sowjanya Komatineni =D0=BF=D0=B8=D1=88= =D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>> On 7/16/19 2:21 PM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>>>> 17.07.2019 0:12, Sowjanya Komatineni =D0=BF=D0=B8=D1= =88=D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>>>> On 7/16/19 1:47 PM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>>>>>> 16.07.2019 22:26, Sowjanya Komatineni =D0=BF=D0=B8= =D1=88=D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>>>>>> On 7/16/19 11:43 AM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>>>>>>>> 16.07.2019 21:30, Sowjanya Komatineni =D0=BF=D0= =B8=D1=88=D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>>>>>>>> On 7/16/19 11:25 AM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>> 16.07.2019 21:19, Sowjanya Komatineni =D0=BF=D0= =B8=D1=88=D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 7/16/19 9:50 AM, Sowjanya Komatineni wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On 7/16/19 8:00 AM, Dmitry Osipenko wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 16.07.2019 11:06, Peter De Schrijver =D0=BF= =D0=B8=D1=88=D0=B5=D1=82: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, Jul 16, 2019 at 03:24:26PM +0800, >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Joseph >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Lo wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> OK, Will add to CPUFreq driver... >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The other thing that also need >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> attention is >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> that T124 CPUFreq >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> driver >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> implicitly relies on DFLL driver to be >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> probed >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> first, which is >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> icky. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Should I add check for successful dfll cl= k >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> register explicitly in >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPUFreq driver probe and defer till dfll >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> clk >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> registers? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Probably you should use the "device links". >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> See >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [1][2] for the >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> example. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [1] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://elixir.bootlin.com/linux/v5.2.1/sour= ce/drivers/gpu/drm/tegra/dc.c#L2383 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [2] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://www.kernel.org/doc/html/latest/drive= r-api/device_link.html >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Return EPROBE_DEFER instead of EINVAL if >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> device_link_add() fails. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> use of_find_device_by_node() to get the DFLL= 's >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> device, see [3]. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> [3] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://git.kernel.org/pub/scm/linux/kernel/= git/next/linux-next.git/tree/drivers/devfreq/tegra20-devfreq.c#n100 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Will go thru and add... >>>>>>>>>>>>>>>>>>>>>>>>>>> Looks like I initially confused this case with >>>>>>>>>>>>>>>>>>>>>>>>>>> getting >>>>>>>>>>>>>>>>>>>>>>>>>>> orphaned clock. >>>>>>>>>>>>>>>>>>>>>>>>>>> I'm now seeing that the DFLL driver registers t= he >>>>>>>>>>>>>>>>>>>>>>>>>>> clock and then >>>>>>>>>>>>>>>>>>>>>>>>>>> clk_get(dfll) should be returning EPROBE_DEFER >>>>>>>>>>>>>>>>>>>>>>>>>>> until >>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL driver is >>>>>>>>>>>>>>>>>>>>>>>>>>> probed, hence everything should be fine as-is a= nd >>>>>>>>>>>>>>>>>>>>>>>>>>> there is no real >>>>>>>>>>>>>>>>>>>>>>>>>>> need >>>>>>>>>>>>>>>>>>>>>>>>>>> for the 'device link'. Sorry for the confusion! >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Sorry, I didn't follow the mail thread. Ju= st >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> regarding the DFLL >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> part. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> As you know it, the DFLL clock is one of t= he >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPU >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> clock sources and >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> integrated with DVFS control logic with th= e >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> regulator. We will not >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> switch >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPU to other clock sources once we >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> switched to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL. Because the >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPU has >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> been regulated by the DFLL HW with the DVF= S >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> table >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (CVB or OPP >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> table >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> you see >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> in the driver.). We shouldn't reparent it = to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> other sources with >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> unknew >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> freq/volt pair. That's not guaranteed to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> work. We >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> allow switching to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> open-loop mode but different sources. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Okay, then the CPUFreq driver will have to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> enforce >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL freq to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PLLP's >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> rate before switching to PLLP in order to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> have a >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> proper CPU voltage. >>>>>>>>>>>>>>>>>>>>>>>>>>>>> PLLP freq is safe to work for any CPU voltage= . >>>>>>>>>>>>>>>>>>>>>>>>>>>>> So no >>>>>>>>>>>>>>>>>>>>>>>>>>>>> need to enforce >>>>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL freq to PLLP rate before changing CCLK_G >>>>>>>>>>>>>>>>>>>>>>>>>>>>> source >>>>>>>>>>>>>>>>>>>>>>>>>>>>> to PLLP during >>>>>>>>>>>>>>>>>>>>>>>>>>>>> suspend >>>>>>>>>>>>>>>>>>>>>>>>>>>> Sorry, please ignore my above comment. During >>>>>>>>>>>>>>>>>>>>>>>>>>>> suspend, need to change >>>>>>>>>>>>>>>>>>>>>>>>>>>> CCLK_G source to PLLP when dfll is in closed >>>>>>>>>>>>>>>>>>>>>>>>>>>> loop >>>>>>>>>>>>>>>>>>>>>>>>>>>> mode first and >>>>>>>>>>>>>>>>>>>>>>>>>>>> then >>>>>>>>>>>>>>>>>>>>>>>>>>>> dfll need to be set to open loop. >>>>>>>>>>>>>>>>>>>>>>>>>>> Okay. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> And I don't exactly understand why we >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> need to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> switch to PLLP in >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPU >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> idle >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> driver. Just keep it on CL-DVFS mode all t= he >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> time. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In SC7 entry, the dfll suspend function >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> moves it >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the open-loop >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> mode. That's >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all. The sc7-entryfirmware will handle >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the rest >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> of the sequence to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> turn off >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the CPU power. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> In SC7 resume, the warmboot code will hand= le >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sequence to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> turn on >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> regulator and power up the CPU cluster. An= d >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> leave >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> it on PLL_P. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> After >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> resuming to the kernel, we re-init DFLL, >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> restore >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the CPU clock >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> policy (CPU >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> runs on DFLL open-loop mode) and then >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> moving to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> close-loop mode. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The DFLL is re-inited after switching CCLK t= o >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> parent during of >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> early clocks-state restoring by CaR driver. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hence >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> instead of having >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> odd >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> hacks in the CaR driver, it is much nicer to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> have a >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> proper suspend-resume sequencing of the devi= ce >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> drivers. In this case >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPUFreq >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> driver is the driver that enables DFLL and >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> switches >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPU to that >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> clock >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> source, which means that this driver is also >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> should >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> be responsible for >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> management of the DFLL's state during of >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> suspend/resume process. If >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CPUFreq driver disables DFLL during suspend >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> and >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> re-enables it >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> during >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> resume, then looks like the CaR driver hacks >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> around >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DFLL are not >>>>>>>>>>>>>>>>>>>>>>>>>>>>>> needed. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The DFLL part looks good to me. BTW, >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> change the >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> patch subject to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> "Add >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> suspend-resume support" seems more >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> appropriate to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> me. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> To clarify this, the sequences for DFLL use >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> are as >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> follows (assuming >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> all >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> required DFLL hw configuration has been don= e) >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Switch to DFLL: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 0) Save current parent and frequency >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 1) Program DFLL to open loop mode >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 2) Enable DFLL >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 3) Change cclk_g parent to DFLL >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> For OVR regulator: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 4) Change PWM output pin from tristate to >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> output >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 5) Enable DFLL PWM output >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> For I2C regulator: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 4) Enable DFLL I2C output >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 6) Program DFLL to closed loop mode >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Switch away from DFLL: >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 0) Change cclk_g parent to PLLP so the CPU >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> frequency is ok for >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> any >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> vdd_cpu voltage >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 1) Program DFLL to open loop mode >>>>>>>>>>>>>>>>>>>>>>>>>>>> I see during switch away from DFLL (suspend), >>>>>>>>>>>>>>>>>>>>>>>>>>>> cclk_g >>>>>>>>>>>>>>>>>>>>>>>>>>>> parent is not >>>>>>>>>>>>>>>>>>>>>>>>>>>> changed to PLLP before changing dfll to open >>>>>>>>>>>>>>>>>>>>>>>>>>>> loop >>>>>>>>>>>>>>>>>>>>>>>>>>>> mode. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Will add this ... >>>>>>>>>>>>>>>>>>>>>>>>>>> The CPUFreq driver switches parent to PLLP duri= ng >>>>>>>>>>>>>>>>>>>>>>>>>>> the >>>>>>>>>>>>>>>>>>>>>>>>>>> probe, similar >>>>>>>>>>>>>>>>>>>>>>>>>>> should be done on suspend. >>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>> I'm also wondering if it's always safe to >>>>>>>>>>>>>>>>>>>>>>>>>>> switch to >>>>>>>>>>>>>>>>>>>>>>>>>>> PLLP in the probe. >>>>>>>>>>>>>>>>>>>>>>>>>>> If CPU is running on a lower freq than PLLP, th= en >>>>>>>>>>>>>>>>>>>>>>>>>>> some >>>>>>>>>>>>>>>>>>>>>>>>>>> other more >>>>>>>>>>>>>>>>>>>>>>>>>>> appropriate intermediate parent should be >>>>>>>>>>>>>>>>>>>>>>>>>>> selected. >>>>>>>>>>>>>>>>>>>>>>>>>> CPU parents are PLL_X, PLL_P, and dfll. PLL_X >>>>>>>>>>>>>>>>>>>>>>>>>> always >>>>>>>>>>>>>>>>>>>>>>>>>> runs at higher >>>>>>>>>>>>>>>>>>>>>>>>>> rate >>>>>>>>>>>>>>>>>>>>>>>>>> so switching to PLL_P during CPUFreq probe >>>>>>>>>>>>>>>>>>>>>>>>>> prior to >>>>>>>>>>>>>>>>>>>>>>>>>> dfll clock enable >>>>>>>>>>>>>>>>>>>>>>>>>> should be safe. >>>>>>>>>>>>>>>>>>>>>>>>> AFAIK, PLLX could run at ~200MHz. There is also a >>>>>>>>>>>>>>>>>>>>>>>>> divided output of >>>>>>>>>>>>>>>>>>>>>>>>> PLLP >>>>>>>>>>>>>>>>>>>>>>>>> which CCLKG supports, the PLLP_OUT4. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> Probably, realistically, CPU is always running >>>>>>>>>>>>>>>>>>>>>>>>> off a >>>>>>>>>>>>>>>>>>>>>>>>> fast PLLX during >>>>>>>>>>>>>>>>>>>>>>>>> boot, but I'm wondering what may happen on KEXEC.= I >>>>>>>>>>>>>>>>>>>>>>>>> guess ideally CPUFreq driver should also have a >>>>>>>>>>>>>>>>>>>>>>>>> 'shutdown' callback to teardown DFLL >>>>>>>>>>>>>>>>>>>>>>>>> on a reboot, but likely that there are other >>>>>>>>>>>>>>>>>>>>>>>>> clock-related problems as >>>>>>>>>>>>>>>>>>>>>>>>> well that may break KEXEC and thus it is not very >>>>>>>>>>>>>>>>>>>>>>>>> important at the >>>>>>>>>>>>>>>>>>>>>>>>> moment. >>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>> [snip] >>>>>>>>>>>>>>>>>>>>>>>> During bootup CPUG sources from PLL_X. By PLL_P >>>>>>>>>>>>>>>>>>>>>>>> source >>>>>>>>>>>>>>>>>>>>>>>> above I meant >>>>>>>>>>>>>>>>>>>>>>>> PLL_P_OUT4. >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> As per clock policies, PLL_X is always used for hi= gh >>>>>>>>>>>>>>>>>>>>>>>> freq >>>>>>>>>>>>>>>>>>>>>>>> like >>>>>>>>>>>>>>>>>>>>>>>>> 800Mhz >>>>>>>>>>>>>>>>>>>>>>>> and for low frequency it will be sourced from PLLP= . >>>>>>>>>>>>>>>>>>>>>>> Alright, then please don't forget to pre-initialize >>>>>>>>>>>>>>>>>>>>>>> PLLP_OUT4 rate to a >>>>>>>>>>>>>>>>>>>>>>> reasonable value using tegra_clk_init_table or >>>>>>>>>>>>>>>>>>>>>>> assigned-clocks. >>>>>>>>>>>>>>>>>>>>>> PLLP_OUT4 rate update is not needed as it is safe to >>>>>>>>>>>>>>>>>>>>>> run at >>>>>>>>>>>>>>>>>>>>>> 408Mhz because it is below fmax @ Vmin >>>>>>>>>>>>>>>>>>>>> So even 204MHz CVB entries are having the same >>>>>>>>>>>>>>>>>>>>> voltage as >>>>>>>>>>>>>>>>>>>>> 408MHz, correct? It's not instantly obvious to me >>>>>>>>>>>>>>>>>>>>> from the >>>>>>>>>>>>>>>>>>>>> DFLL driver's code where the fmax @ Vmin is defined, >>>>>>>>>>>>>>>>>>>>> I see >>>>>>>>>>>>>>>>>>>>> that there is the min_millivolts >>>>>>>>>>>>>>>>>>>>> and frequency entries starting from 204MHZ defined >>>>>>>>>>>>>>>>>>>>> per-table. >>>>>>>>>>>>>>>>>>>> Yes at Vmin CPU Fmax is ~800Mhz. So anything below tha= t >>>>>>>>>>>>>>>>>>>> will >>>>>>>>>>>>>>>>>>>> work at Vmin voltage and PLLP max is 408Mhz. >>>>>>>>>>>>>>>>>>> Thank you for the clarification. It would be good to ha= ve >>>>>>>>>>>>>>>>>>> that >>>>>>>>>>>>>>>>>>> commented >>>>>>>>>>>>>>>>>>> in the code as well. >>>>>>>>>>>>>>>>>> OK, Will add... >>>>>>>>>>>>>>>>> Regarding, adding suspend/resume to CPUFreq, CPUFreq >>>>>>>>>>>>>>>>> suspend >>>>>>>>>>>>>>>>> happens very early even before disabling non-boot CPUs an= d >>>>>>>>>>>>>>>>> also >>>>>>>>>>>>>>>>> need to export clock driver APIs to CPUFreq. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Was thinking of below way of implementing this... >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Clock DFLL driver Suspend: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0= =C2=A0=C2=A0 - Save CPU clock policy registers, and >>>>>>>>>>>>>>>>> Perform >>>>>>>>>>>>>>>>> dfll >>>>>>>>>>>>>>>>> suspend which sets in open loop mode >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> CPU Freq driver Suspend: does nothing >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Clock DFLL driver Resume: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0= =C2=A0=C2=A0 - Re-init DFLL, Set in Open-Loop mode, >>>>>>>>>>>>>>>>> restore >>>>>>>>>>>>>>>>> CPU >>>>>>>>>>>>>>>>> Clock policy registers which actually sets source to DFLL >>>>>>>>>>>>>>>>> along >>>>>>>>>>>>>>>>> with other CPU Policy register restore. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> CPU Freq driver Resume: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0= =C2=A0=C2=A0 - do clk_prepare_enable which acutally sets >>>>>>>>>>>>>>>>> DFLL in >>>>>>>>>>>>>>>>> Closed loop mode >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Adding one more note: Switching CPU Clock to PLLP is not >>>>>>>>>>>>>>>>> needed >>>>>>>>>>>>>>>>> as CPU CLock can be from dfll in open-loop mode as DFLL >>>>>>>>>>>>>>>>> is not >>>>>>>>>>>>>>>>> disabled anywhere throught the suspend/resume path and SC= 7 >>>>>>>>>>>>>>>>> entry >>>>>>>>>>>>>>>>> FW and Warm boot code will switch CPU source to PLLP. >>>>>>>>>>>>>>> Since CPU resumes on PLLP, it will be cleaner to suspend >>>>>>>>>>>>>>> it on >>>>>>>>>>>>>>> PLLP as well. And besides, seems that currently disabling >>>>>>>>>>>>>>> DFLL >>>>>>>>>>>>>>> clock will disable DFLL completely and then you'd want to >>>>>>>>>>>>>>> re-init >>>>>>>>>>>>>>> the DFLL on resume any ways. So better to just disable DFLL >>>>>>>>>>>>>>> completely on suspend, which should happen on >>>>>>>>>>>>>>> clk_disable(dfll). >>>>>>>>>>>>>> Will switch to PLLP during CPUFreq suspend. With decision of >>>>>>>>>>>>>> using >>>>>>>>>>>>>> clk_disable during suspend, its mandatory to switch to PLLP = as >>>>>>>>>>>>>> DFLL >>>>>>>>>>>>>> is completely disabled. >>>>>>>>>>>>>> >>>>>>>>>>>>>> My earlier concern was on restoring CPU policy as we can't d= o >>>>>>>>>>>>>> that >>>>>>>>>>>>>> from CPUFreq driver and need export from clock driver. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Clear now and will do CPU clock policy restore in after dfll >>>>>>>>>>>>>> re-init. >>>>>>>>>>>>> Why the policy can't be saved/restored by the CaR driver as a >>>>>>>>>>>>> context of any other clock? >>>>>>>>>>>> restoring cpu clock policy involves programming source and >>>>>>>>>>>> super_cclkg_divider. >>>>>>>>>>>> >>>>>>>>>>>> cclk_g is registered as clk_super_mux and it doesn't use >>>>>>>>>>>> frac_div ops >>>>>>>>>>>> to do save/restore its divider. >>>>>>>>>>> That can be changed of course and I guess it also could be as >>>>>>>>>>> simple as >>>>>>>>>>> saving and restoring of two raw u32 values of the policy/divide= r >>>>>>>>>>> registers. >>>>>>>>>>> >>>>>>>>>>>> Also, during clock context we cant restore cclk_g as cclk_g >>>>>>>>>>>> source >>>>>>>>>>>> will be dfll and dfll will not be resumed/re-initialized by th= e >>>>>>>>>>>> time >>>>>>>>>>>> clk_super_mux save/restore happens. >>>>>>>>>>>> >>>>>>>>>>>> we can't use save/restore context for dfll clk_ops because >>>>>>>>>>>> dfllCPU_out parent to CCLK_G is first in the clock tree and >>>>>>>>>>>> dfll_ref >>>>>>>>>>>> and dfll_soc peripheral clocks are not restored by the time df= ll >>>>>>>>>>>> restore happens. Also dfll peripheral clock enables need to be >>>>>>>>>>>> restored before dfll restore happens which involves programmin= g >>>>>>>>>>>> dfll >>>>>>>>>>>> controller for re-initialization. >>>>>>>>>>>> >>>>>>>>>>>> So dfll resume/re-init is done in clk-tegra210 at end of all >>>>>>>>>>>> clocks >>>>>>>>>>>> restore in V5 series but instead of in clk-tegra210 driver I >>>>>>>>>>>> moved >>>>>>>>>>>> now to dfll-fcpu driver pm_ops as all dfll dependencies will b= e >>>>>>>>>>>> restored thru clk_restore_context by then. This will be in V6. >>>>>>>>>>> Since DFLL is now guaranteed to be disabled across CaR >>>>>>>>>>> suspend/resume >>>>>>>>>>> (hence it has nothing to do in regards to CCLK) and given that >>>>>>>>>>> PLLs >>>>>>>>>>> state is restored before the rest of the clocks, I don't see wh= y >>>>>>>>>>> not to >>>>>>>>>>> implement CCLK save/restore in a generic fasion. CPU policy >>>>>>>>>>> wull be >>>>>>>>>>> restored to either PLLP or PLLX (if CPUFreq driver is disabled)= . >>>>>>>>>>> >>>>>>>>>> CCLK_G save/restore should happen in clk_super_mux ops >>>>>>>>>> save/context and >>>>>>>>>> clk_super_mux save/restore happens very early as cclk_g is first >>>>>>>>>> in the >>>>>>>>>> clock tree and save/restore traverses through the tree top-botto= m >>>>>>>>>> order. >>>>>>>>> If CCLK_G is restored before the PLLs, then just change the clock= s >>>>>>>>> order >>>>>>>>> such that it won't happen. >>>>>>>>> >>>>>>>> I dont think we can change clocks order for CCLK_G. >>>>>>>> >>>>>>>> During bootup, cclk_g is registered after all pll's and peripheral >>>>>>>> clocks which is the way we wanted, So cclk_g will be the first >>>>>>>> one in >>>>>>>> the clk list as clk_register adds new clock first in the list. >>>>>>>> >>>>>>>> When clk_save_context and clk_restore_context APIs iterates over t= he >>>>>>>> list, cclk_g is the first >>>>>>> Looking at clk_core_restore_context(), I see that it walks up CLKs >>>>>>> list >>>>>>> from parent to children, hence I don't understand how it can ever >>>>>>> happen >>>>>>> that CCLK will be restored before the parent. The clocks registrati= on >>>>>>> order doesn't matter at all in that case. >>>>>> yes from parent to children and dfllCPU_out is the top in the list a= nd >>>>>> its child is cclk_g. >>>>>> >>>>>> the way clocks are registered is the order I see in the clock list a= nd >>>>>> looking into clk_register API it adds new node first in the list. >>>>>> >>>>> cclkg_g & dfll register happens after all plls and peripheral clocks = as >>>>> it need ref, soc and peripheral clocks to be enabled. >>>>>> So they are the last to get registered and so becomes first in the >>>>>> list. >>>>>> >>>>>> During save/restore context, it traverses thru this list and first i= n >>>>>> the list is dfllcpu_OUT (parent) and its child (cclk_g) >>>>>> >>>>>> saving should not be an issue at all but we cant restore cclk_g/dfll >>>>>> in normal way thru clk_ops restore as plls and peripherals restore >>>>>> doesn't happen by that time. >>>>>> >>>>> I was referring to clk_restore_context where it iterates thru root li= st >>>>> and for each core from the root list clk_core_restore does restore of >>>>> parent and children. >>>>> >>>>> dfllCPU_Out gets first in the list and its child is cclk_g >>>>> >>>>> https://elixir.bootlin.com/linux/v5.2.1/source/drivers/clk/clk.c#L110= 5 >>>> What list you're talking about? clk_summary? It shows current *active* >>>> clocks configuration, if you'll try to disable CPUFreq driver then the >>>> parent of CCLK_G should be PLLX. Similarly when CPU is reparented to >>>> PLLP on driver's suspend, then PLLP is the parent. >>>> >>>>>>>>>> DFLL enable thru CPUFreq resume happens after all >>>>>>>>>> clk_restore_context >>>>>>>>>> happens. So during clk_restore_context, dfll re-init doesnt happ= en >>>>>>>>>> and >>>>>>>>>> doing cpu clock policy restore during super_mux clk_ops will >>>>>>>>>> crash as >>>>>>>>>> DFLL is not initialized and its clock is not enabled but CPU clo= ck >>>>>>>>>> restore sets source to DFLL if we restore during super_clk_mux >>>>>>>>> If CPU was suspended on PLLP, then it will be restored on PLLP by >>>>>>>>> CaR. I >>>>>>>>> don't understand what DFLL has to do with the CCLK in that case >>>>>>>>> during >>>>>>>>> the clocks restore. >>>>>>>> My above comment is in reference to your request of doing >>>>>>>> save/restore >>>>>>>> for cclk_g in normal fashion thru save/restore context. Because >>>>>>>> of the >>>>>>>> clk order I mentioned above, we cclk_g will be the first one to >>>>>>>> go thru >>>>>>>> save/context. >>>>>>>> >>>>>>>> During save_context of cclk_g, source can be from PLLX, dfll. >>>>>>>> >>>>>>>> Issue will be when we do restore during clk_restore_context of >>>>>>>> cclk_g as >>>>>>>> by that time PLLX/dfll will not be restored. >>>>>>>> >>>>>>> Seems we already agreed that DFLL will be disabled by the CPUFreq >>>>>>> driver >>>>>>> on suspend. Hence CCLK can't be from DFLL if CPU is reparented to >>>>>>> PLLP >>>>>>> on CPUFreq driver's suspend, otherwise CPU keeps running from a >>>>>>> boot-state PLLX if CPUFreq driver is disabled. >>>>>> Yes suspend should not be an issue but issue will be during resume >>>>>> where if we do cclk_g restore in normal way thru clk_restore_context= , >>>>>> cclk_g restore happens very early as dfllCPU out is the first one th= at >>>>>> goes thru restore context and plls/peripherals are not resumed by >>>>>> then. >>>>>> >>>>>> CPU runs from PLLX if dfll clock enable fails during boot. So when i= t >>>>>> gets to suspend, we save CPU running clock source as either PLLX or >>>>>> DFLL and then we switch to PLLP. >>>>>> >>>>>> >>>>>> On resume, CPU runs from PLLP by warm boot code and we need to resto= re >>>>>> back its source to the one it was using from saved source context >>>>>> (which can be either PLLX or DFLL) >>>>>> >>>>>> So PLLs & DFLL resume need to happen before CCLKG restore/resume. >>>>>> >>>>>> >>>>>> With all above discussions, we do DFLL disable in CPUFreq driver on >>>>>> suspend and on CPUFreq resume we enable DFLL back and restore CPU >>>>>> clock source it was using during suspend (which will be either PLLX = if >>>>>> dfll enable fails during probe or it will be using DFLL). >>>> During suspend CPU's parent shall be PLLP and not DFLL (note that it i= s >>>> disabled) after reparenting to PLLP by the CPUFreq driver. >>>> >>> CPU source context should be saved before switching to safe source of >>> PLLP as on resume we need to restore back to source it was using >>> before we switch to safe source during suspend entry. >>> >>> So saved context for CPU Source will be either dfll or PLLX >>> >> PLLP reparenting is only during suspend/entry to have it as safe source >> but actual CPU source it was running from before suspending is either >> dfll/pllx which should be the one to be restored on CPUFreq resume. >> Resume happens with CPU running from PLLP till it gets to the point of >> restoring its original source (dfll or pllx) > CaR should restore CPU to PLLP or PLLX, while CPUFreq driver restores > CPU to DFLL. Please see more comments below. > >>>>>> So i was trying to say dfll/cclk_g restore can't be done in normal w= ay >>>>>> thru clk_ops save/restore context >>>> Let's see what happens if CPUFreq is active: >>>> >>>> 1. CPUFreq driver probe happens >>>> =C2=A0=C2=A0=C2=A0=C2=A02. CPU is reparented to PLLP >>>> =C2=A0=C2=A0=C2=A0=C2=A03. DFLL inited >>>> =C2=A0=C2=A0=C2=A0=C2=A04. CPU is reparented to DFLL >>>> >>>> 5. CPUFreq driver suspend happens >>>> =C2=A0=C2=A0=C2=A0=C2=A06. CPU is reparented to PLLP >>>> =C2=A0=C2=A0=C2=A0=C2=A07. DFLL is disabled >>>> >>>> 8. Car suspend happens >>>> =C2=A0=C2=A0=C2=A0=C2=A09. DFLL context saved >>>> =C2=A0=C2=A0=C2=A0=C2=A010. PLLP/PLLX context saved >>>> =C2=A0=C2=A0=C2=A0=C2=A011. CCLK context saved >>>> >>>> 12. Car resume happens >>>> =C2=A0=C2=A0=C2=A0=C2=A013. DFLL context restored >>>> =C2=A0=C2=A0=C2=A0=C2=A014. PLLP/PLLX context restored >>>> =C2=A0=C2=A0=C2=A0=C2=A015. CCLK context restored >>>> >>>> 16. CPUFreq driver resume happens >>>> =C2=A0=C2=A0=C2=A0=C2=A017. DFLL re-inited >>>> =C2=A0=C2=A0=C2=A0=C2=A018. CPU is reparented to DFLL >>> >>> Below is the order of sequence it should be based on the order of clk >>> register. >>> >>> My comments inline in this sequence. >>> >>> 1. CPUFreq driver probe happens >>> =C2=A0=C2=A0=C2=A0=C2=A02. CPU is reparented to PLLP >>> =C2=A0=C2=A0=C2=A0=C2=A03. DFLL inited >>> =C2=A0=C2=A0=C2=A0=C2=A04. CPU is reparented to DFLL >>> >>> >>> 5. CPUFreq driver suspend happens >>> =C2=A0=C2=A0=C2=A0=C2=A06. Save CPU source which could be either dfll = or pllx > Please see my next comment. > >>> =C2=A0=C2=A0=C2=A0=C2=A07. CPU is reparented to safe known source PLLP >>> =C2=A0=C2=A0=C2=A0=C2=A08. DFLL is disabled >>> >>> 8. Car suspend happens >>> =C2=A0=C2=A0=C2=A0=C2=A09. DFLL context saved (With DFLL disabled in C= PUFreq suspend, >>> nothing to be saved here as last freq req will always be saved). >>> =C2=A0=C2=A0=C2=A0=C2=A010. CCLK context saved (CPU clock source will = be saved in CPUFreq >>> driver suspend which could be either dfll or pllx) > That I don't understand. The CPU's clock source state should be saved at > the moment of the CaR's suspending (i.e. CCLK policy will be set to PLLP > or PLLX) and then CCLK state should be also restored by the CaR in step 1= 4. CPU clock to be saved and restored should be the source used before we=20 switch it to safe PLLP for suspend/resume operation. This original source could be either PLLX or DFLL which it was using=20 before we disable DFLL during CPU Freq suspend. If we save CPU clock source at moment of CAR suspending, it will be PLLP=20 as we switch to safe PLLP in CPUFreq driver suspend. Infact, we dont need to restore CPU clock source to PLLP anywhere in=20 resume as it comes up with PLLP source from warm boot code itself. But we need to restore CPU source to original source it was using before=20 we switch to safe PLLP source for suspend operation. This original=20 source could be PLLX/DFLL and this should be re-stored in CPUFreq resume=20 as by this time PLLs and peripherals are restored and dfll is=20 re-initialized. So saving actual CPU source before switching to intermediate safe PLLP=20 in CPUFreq driver and then restoring back during CPUFreq resume should=20 be good as CPUFreq resume happens right after all clocks (plls restore,=20 peripherals restore, dfll resume) > CPUFreq driver should only switch CPU to PLLP and disable DFLL on > suspend in step 5, that's it. On resume CPUFreq driver will restore CPU > to DFLL in step 18. Also I don't think we should hard-code to force CPU source to DFLL on=20 CPUFreq resume. Reason is during CPU Probe when it tries to switch to dfll source, for=20 some reason if dfll enable fails it sets CPU to its original source=20 which will be PLLX. So CPU source could be either DFLL or PLLX in CPUFreq=20 tegra124_cpu_switch_to_dfll >>> =C2=A0=C2=A0=C2=A0=C2=A011. PLLP/PLLX context saved >>> =C2=A0=C2=A0=C2=A0=C2=A012. Peripheral Clock saved >>> >>> 12. Car resume happens >>> =C2=A0=C2=A0=C2=A0=C2=A013. DFLL context restored : No DFLL context to= be restored and we >>> only need to reinitialize DFLL and re-initialize can't be done here as >>> this is the 1st to get restored and PLL/Peripheral clocks are not >>> restored by this time. So we can't use clk_ops restore for DFLL > It looks to me that clk_core_restore_context() should just do > hlist_for_each_entry *_reverse*. Don't you think so? Thought of that but this is in core driver and is used by other=20 non-tegra clock driver and not sure if that impacts for those. But with decision of switching CPUFreq with dfll clock enable/disable=20 during CPUFreq suspend/resume, we can re-init dfll during dfll-fcpu=20 driver resume and we don't need CCLK save/restore. >>> =C2=A0=C2=A0=C2=A0=C2=A014. CCLK context restored >>> CCLK cant be restored here as context could be either dfll or pllx >>> which is the source orginally it was actually using before we force >>> switch to safe PLLP for suspend entry. So we can't use clk_ops restore >>> for DFLL > See my comment to step 10. CCLK should be restored to the *CaR's saved* > context, which is either PLLX or PLLP policy. > >>> 15. PLLP/PLLX context restored >>> =C2=A0=C2=A0=C2=A0=C2=A016. Peripheral context restored >>> >>> 16. CPUFreq driver resume happens >>> =C2=A0=C2=A0=C2=A0=C2=A017. DFLL re-inited (Invoking DFLL re-init in C= PUFreq resume need >>> exporting DFLL reinit from Clock driver to CPUFreq driver) > Will be nice if clk_enable(dfll) could be enough to re-init DFLL. That > should achievable with my next comment to step 18. > >>> =C2=A0=C2=A0=C2=A0=C2=A018. CPU is reparented to DFLL or PLLX based on= saved context from >>> step 9. >>> >>> Note: instead of exporting, we can do DFLL re-init from clock-dfll >>> driver itself thru dfll-fcpu pm_ops resume. So dfll will be >>> re-initialized by the time CPUFreq driver resumes and switches to use >>> DFLL source. >>> > Yes, I guess DFLL hardware should be fully reset on DFLL's driver resume > to be on a safe side any ways. > > But(!) we could probably just fix clk_core_restore_context(), like I > suggested in step 13. Then DFLL clock could use generic save / restore > context and CPUFreq driver won't have to do anything at all because DFLL > clock will be saved first and resumed *after* all of the peripherals by > the CCF. In the end CCLK will be switched to DFLL by the CCF restore as > well.