From mboxrd@z Thu Jan 1 00:00:00 1970 From: a.aubert@overkiz.com (Antoine Aubert) Date: Tue, 6 Oct 2015 17:26:26 +0200 Subject: at91sam9 Main crystal frequency problems In-Reply-To: <20151006161244.06f3ceb4@bbrezillon> References: <55ED3D3B.8060700@overkiz.com> <20150908181212.0b4336f0@bbrezillon> <55F6C07C.8080803@overkiz.com> <20151006161244.06f3ceb4@bbrezillon> Message-ID: <5613E822.2020004@overkiz.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Boris Le 06/10/2015 16:12, Boris Brezillon a ?crit : > Hi Antoine, > > On Mon, 14 Sep 2015 14:41:32 +0200 > Antoine Aubert wrote: > >> Hi Boris, >> >> Thank you for your help. I have some news thanks to traces in clk driver. > > Any progress regarding this problem. I think Jiri (in Cc) has pretty > much the same problem (see this thread [1]). > IIRC, activating NO_HZ_IDLE solved the problem for you, but have you > find the root cause? I'm not sure that the same issue. Here I don't have slow xtal. What I found: * DTB was not up to date (build with an other kernel version) Since we start from kexec, we added --dtb option * slow_xtal wasn't disabled in our DTS * defconfig was outdated What i did first: * updated the dts, disabled slow xtal * Update DTB * activating NO_HZ_IDLE > 20d updtime without WRST Today what I did: * use LTS last kernel: 4.1.6 * updated the dts, disabled slow xtal * generate config from scratch using "make ARCH=arm at91_dt_defconfig" (without NO_HZ_IDLE= 12h uptime, at this time no WRST > > Best Regards, > > Boris > > [1]http://thread.gmane.org/gmane.linux.ports.arm.kernel/413356 > >> >> >> Le 08/09/2015 18:12, Boris Brezillon a ?crit : >>> Hi Antoine, >>> >>> On Mon, 7 Sep 2015 09:31:07 +0200 >>> Antoine Aubert wrote: >>> >>>> Hi, >>>> >>>> I currently bring up a board based on AT91SAM9G25cu, and I having >>>> problems of watchdogs resets. >>>> >>>> We use linux-4.04 mainline, and i found some weird warnings on kernel >>>> traces, concerning main clk. >>>> >>>> [ 0.000000] Main crystal frequency not set, using approximate value >>>> [ 0.000000] master clk is overclocked >>>> [ 0.000000] sched_clock: 32 bits at 128 Hz, resolution 7812500ns, >>>> wraps every 16777216000000000ns >>>> [ 0.007812] Calibrating delay loop... 198.76 BogoMIPS (lpj=775168) >>>> >>>> I set crystal clock in the DT, but it doesn't seems to work.. I feel >>>> that the board works out of the specified range. >>> >>> According to your clk_summary dump that's not the case. >>> >>>> >>>> So here comes my questions: >>>> Can there be a relationship with watchdog problems ? (1 per day) >>> >>> I'd say no, but could you tell me more about your watchdog issues. >> >> Yet, we did not take the analysis. We just observed these resets. >> >> But, I found a clue: >> We recently removed the slow clock to the PCB. I forgot to disabled the >> slow_xtal. :/ >> Can there be a link ? (I think so...) >> >>> >>>> Why is it that the frequency of Crystal is not found ? >>> >>> That's a good question, and honestly I don't. Everything seems to be >>> defined properly in your device tree. >>> >>> Could you add some traces in the fixed-rate clk driver [1] to see if the >>> main_xtal is correctly registered and if its registration occurs before >>> the main_osc registration? >> >> On our board, there is two kernel boot phases. >> >> First, we boot from at91-bootstrap. >> Second we launched kexec with an other kernel. >> >> I found that the device tree is well loaded from the at91-bootstrap. Any >> crystal issues. But, on kexec --exec, (with the same kernel) those >> issues appears. (see dmesg attached) >> >> If I launch kexec with --dtb, it's working ... >> I thought kexec keep old dtb. Was I wrong ? >> >>> >>> Best Regards, >>> >>> Boris >>> >>> [1]https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/drivers/clk/clk-fixed-rate.c?id=refs/tags/v4.0.4#n115 >>> >> >> Best regards, >> Antoine Aubert >> a.aubert at overkiz.com > > > Antoine Aubert a.aubert at overkiz.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 473 bytes Desc: OpenPGP digital signature URL: