From mboxrd@z Thu Jan 1 00:00:00 1970 From: siarhei.siamashka@gmail.com (Siarhei Siamashka) Date: Thu, 19 Mar 2015 12:28:13 +0200 Subject: [PATCH 1/2] ARM: dts: sun4i: a10-lime: Override and remove 1008MHz OPP setting In-Reply-To: References: <1426732773-7179-1-git-send-email-wens@csie.org> <1426732773-7179-2-git-send-email-wens@csie.org> <20150319085716.75d3ce76@i7> Message-ID: <20150319122813.39112da2@i7> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 19 Mar 2015 16:17:30 +0800 Chen-Yu Tsai wrote: > On Thu, Mar 19, 2015 at 2:57 PM, Siarhei Siamashka > wrote: > > On Thu, 19 Mar 2015 10:39:32 +0800 > > Chen-Yu Tsai wrote: > > > >> The Olimex A10-Lime is known to be unstable when running at 1008MHz. > >> > >> Signed-off-by: Chen-Yu Tsai > >> --- > >> arch/arm/boot/dts/sun4i-a10-olinuxino-lime.dts | 14 ++++++++++++++ > >> 1 file changed, 14 insertions(+) > >> > >> diff --git a/arch/arm/boot/dts/sun4i-a10-olinuxino-lime.dts b/arch/arm/boot/dts/sun4i-a10-olinuxino-lime.dts > >> index 31dc2f1c3870..16ecb8938e19 100644 > >> --- a/arch/arm/boot/dts/sun4i-a10-olinuxino-lime.dts > >> +++ b/arch/arm/boot/dts/sun4i-a10-olinuxino-lime.dts > >> @@ -74,6 +74,20 @@ > >> status = "okay"; > >> }; > >> > >> +&cpu0 { > >> + /* The A10-Lime is known to be unstable when running at 1008 MHz */ > >> + operating-points = < > >> + /* kHz uV */ > >> + 960000 1400000 > >> + 912000 1400000 > >> + 864000 1300000 > >> + 720000 1200000 > >> + 528000 1100000 > >> + 312000 1000000 > >> + 144000 900000 > >> + >; > >> +}; > >> + > >> &ehci0 { > >> status = "okay"; > >> }; > > > > Thanks for the patch. At least it should make my A10-OLinuXino-LIME > > working without obvious failures out of the box (the U-Boot is still > > another story though and there is a gap during boot up when the board > > is running with unreliable settings, but the probability of a failure > > is rather low). > > > > I should also mention that using 960MHz @1.4V does not fail, but it does > > not have any safety headroom either (the cyan 'sun4i_poorlime' line > > on the plot): > > > > http://people.freedesktop.org/~siamashka/files/20140512/sunxi-cpufreq-plot.png > > > > On the other hand, my board is on the worst part of the spectrum (many > > other a10-lime boards do not fail even at 1008MHz), so maybe having > > extra safety headroom is less necessary. > > > > An interesting question is whether the same problem may be reproducible > > on the Allwinner A10 devices other than A10-OLinuXino-LIME. My original > > problem report > > > > https://www.mail-archive.com/linux-sunxi at googlegroups.com/msg04343.html > > > > mentioned the A10-OLinuXino-LIME rev.A and introduced some sort of > > a bias by itself. At least I have seen people saying something like > > "my a10-lime revision is not rev.A, so it's none of my concern and > > I'm not going to bother running any tests". So far we have accumulated > > reports from 4 or 5 people having this reliability problem on their > > A10-OLinuXino-LIME (various revisions, not just rev.A), but not > > much from the other boards owners. > > > > Anyway, this particular patch is > > Tested-by: Siarhei Siamashka > > Acked-by: Siarhei Siamashka > > Good to hear it works. Did you test all the settings? You have nailed it. I was about to send the results of the full round of tests after running them a bit longer and revoke the initial Tested-by. Turns out that the 312MHz and 144MHz operating points fail to work reliable and tend to deadlock: Testing CPU 0 960 MHz ............................................................ OK 912 MHz ............................................................ OK 864 MHz ............................................................ OK 720 MHz ............................................................ OK 528 MHz ............................................................ OK 312 MHz ............................................................ OK 144 MHz Write failed: Broken pipe Testing CPU 0 960 MHz ............................................................ OK 912 MHz ............................................................ OK 864 MHz ............................................................ OK 720 MHz ............................................................ OK 528 MHz ............................................................ OK 312 MHz .................Write failed: Broken pipe > I copied the wrong settings, from sun5i-a13.dtsi instead of sun4i-a10.dtsi. I guess, this explains the problems at lower operating points. > I'll send a fixed version later. Thanks. -- Best regards, Siarhei Siamashka