Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754862AbbKMSdD (ORCPT ); Fri, 13 Nov 2015 13:33:03 -0500 Received: from arroyo.ext.ti.com ([192.94.94.40]:44478 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754762AbbKMSdB (ORCPT ); Fri, 13 Nov 2015 13:33:01 -0500 From: Felipe Balbi To: Grygorii Strashko , , Daniel Lezcano , Thomas Gleixner , Srinivas Kandagatla , Maxime Coquelin CC: , , , , Arnd Bergmann , John Stultz , Tony Lindgren Subject: Re: [PATCH] clocksource: arm_global_timer: fix suspend resume In-Reply-To: <56462C0A.6070802@ti.com> References: <1447431951-23713-1-git-send-email-grygorii.strashko@ti.com> <87a8qhq284.fsf@saruman.tx.rr.com> <56461688.1090809@ti.com> <87y4e1ol0g.fsf@saruman.tx.rr.com> <56462742.3020300@ti.com> <87si49ojed.fsf@saruman.tx.rr.com> <56462C0A.6070802@ti.com> User-Agent: Notmuch/0.21 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) Date: Fri, 13 Nov 2015 12:32:12 -0600 Message-ID: <87mvuhoimr.fsf@saruman.tx.rr.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5942 Lines: 161 --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, Grygorii Strashko writes: > On 11/13/2015 08:15 PM, Felipe Balbi wrote: >> >> Hi, >> >> Grygorii Strashko writes: >>> On 11/13/2015 07:40 PM, Felipe Balbi wrote: >>>> >>>> Hi, >>>> >>>> Grygorii Strashko writes: >>>>> On 11/13/2015 06:43 PM, Felipe Balbi wrote: >>>>>> >>>>>> Hi, >>>>>> >>>>>> Grygorii Strashko writes: >>>>>>> Now the System stall is observed on TI AM437x based board >>>>>>> (am437x-gp-evm) during resuming from System suspend when ARM Global >>>>>>> timer is selected as clocksource device - SysRq are working, but >>>>>>> nothing else. The reason of stall is that ARM Global timer loses its >>>>>>> contexts. >>>>>>> >>>>>>> The reason of stall is that ARM Global timer loses its contexts dur= ing >>>>>>> System suspend: >>>>>>> GT_CONTROL.TIMER_ENABLE =3D 0 (unbanked) >>>>>>> GT_COUNTERx =3D 0 >>>>>>> >>>>>>> Hence, update ARM Global timer driver to reflect above behaviour >>>>>>> - save GT_CONTROL.TIMER_ENABLE during suspend and restore on resume; >>>>>>> - ensure clocksource and clockevent devices have coresponding flags >>>>>>> (CLOCK_SOURCE_SUSPEND_NONSTOP and CLOCK_EVT_FEAT_C3STOP) set >>>>>>> depending on presence of "always-on" DT property. >>>>>>> >>>>>>> CC: Arnd Bergmann >>>>>>> Cc: John Stultz >>>>>>> Cc: Felipe Balbi >>>>>>> Cc: Tony Lindgren >>>>>>> Signed-off-by: Grygorii Strashko >>>>>>> --- >>>>>>> drivers/clocksource/arm_global_timer.c | 23 +++++++++++++++++++= ++++ >>>>>>> 1 file changed, 23 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clock= source/arm_global_timer.c >>>>>>> index a2cb6fa..1bbaf64 100644 >>>>>>> --- a/drivers/clocksource/arm_global_timer.c >>>>>>> +++ b/drivers/clocksource/arm_global_timer.c >>>>>>> @@ -51,6 +51,8 @@ static void __iomem *gt_base; >>>>>>> static unsigned long gt_clk_rate; >>>>>>> static int gt_ppi; >>>>>>> static struct clock_event_device __percpu *gt_evt; >>>>>>> +static bool gt_always_on; >>>>>>> +static u32 gt_control; >>>>>>> >>>>>>> /* >>>>>>> * To get the value from the Global Timer Counter register proc= eed as follows: >>>>>>> @@ -168,6 +170,9 @@ static int gt_clockevents_init(struct clock_eve= nt_device *clk) >>>>>>> { >>>>>>> int cpu =3D smp_processor_id(); >>>>>>> >>>>>>> + if (!gt_always_on) >>>>>>> + clk->features |=3D CLOCK_EVT_FEAT_C3STOP; >>>>>>> + >>>>>>> clk->name =3D "arm_global_timer"; >>>>>>> clk->features =3D CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONE= SHOT | >>>>>>> CLOCK_EVT_FEAT_PERCPU; >>>>>>> @@ -195,12 +200,25 @@ static cycle_t gt_clocksource_read(struct clo= cksource *cs) >>>>>>> return gt_counter_read(); >>>>>>> } >>>>>>> >>>>>>> +static void gt_suspend(struct clocksource *cs) >>>>>>> +{ >>>>>>> + gt_control =3D readl(gt_base + GT_CONTROL); >>>>>>> +} >>>>>>> + >>>>>>> +static void gt_resume(struct clocksource *cs) >>>>>>> +{ >>>>>>> + /* enables timer on all the cores */ >>>>>>> + writel(gt_control & GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL= ); >>>>>> >>>>>> do you really need to save context if all you restore is TIMER_ENABLE >>>>>> bit ? seems like you could skip gt_suspend altogether. Is there real= ly a >>>>>> situation where this driver is running and GT isn't enabled ? >>>>> >>>>> Now It's not. It's always enabled. I did it because .suspend() is cal= led for >>>>> all registered clock sources regardless of their usage. So, potential= ly >>>>> in the future, at the moment when .suspend() is called it might be di= sabled >>>>> (for example, .enable/disable() callbacks can be added and, if ARM Gl= obal timer >>>>> will not be registered as sched_clock, it will be possible to keep it= disabled >>>>> if not used now). >>>>> >>>>> But It's not essentially now - I can update it and drop save restore. >>>>> Pls, confirm. >>>> >>>> I think it's best to skip suspend completely. You're not restoring >>>> anything you saved during suspend, unless you meant | where you used &. >>>> >>> >>> I didn't get it - I'm restoring one bit(0) only. >> >> that's the point, if you know you're restoring only that bit. Why save >> anything at all ? >> > > i think there are difference between "restoring" and "re-enabling". > "restoring" - assume saving smth.. then restore saving value. > I'm saving & restoring one bit here. with your current suspend/resume, they are the same thing. You save GT_CONTROL contents, timer goes off and looses context, you set ENABLE bit. No difference what so ever. =2D-=20 balbi --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJWRiytAAoJEIaOsuA1yqREQKkP/R6set2PNg1NAq6D6CNBU/7r +eQXNpBlN9pxtzVgcgRCfevOv1qacEaYggIQTyPQwT1S5wR+G1K3nfyWdE2e30pt IVd7skS76lLKICkiTyv6qBgcz9j/TyKx3GBeb5PHgdB7yXQnpaJT5BDzvE7JkeR4 /bTcRlpPR3N2+FsfI4uwhCKkcufDCPDCsLL5ux1YI4D5ekOiBsLPHjti/U6RdxTR 217MMBuW9mZVNawCcqPRNNiwM0pwBXiYwnXzhQ3X0ed33CcmA3aEYiNEsVj0ksgq 8hVmW0qkQindn06dV1PSvhU68cmMLcKfZQS1RfsI6o0oHw4ntPMpfU+aWLS505nQ cDS6zEnE1l0n9IhkZFzz2v3QYZHCPbFoX/1K3fjksNekB6hKODZy6kU/duujcXgI JQqvwVc6Sew1c14mevzg3h87PBXbTdVbrcJ0JafyeSVJB+T59KFACDAtr4ax9bZK VcpWIpU9ioxA+omQCx6VkEcjCv0p52Odc+TU8zeOXOwYvZZna1o6a4pDOnK40La1 NaYgURQNXY8vkwPxB5XeUniUtywv19wobQJZz17wc2A7DKgAitoFCWEDf807ac+x AiUqGyGpMPZevr8GsXRKVGinBMmM7pCVymXP7e+mVJCAqcX50Zxm0ueUyuC11oi9 2xbJRvzCHTacxW1QSF2m =Ba9t -----END PGP SIGNATURE----- --=-=-=-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/