From mboxrd@z Thu Jan 1 00:00:00 1970 From: siarhei.siamashka@gmail.com (Siarhei Siamashka) Date: Thu, 19 Mar 2015 08:57:16 +0200 Subject: [PATCH 1/2] ARM: dts: sun4i: a10-lime: Override and remove 1008MHz OPP setting In-Reply-To: <1426732773-7179-2-git-send-email-wens@csie.org> References: <1426732773-7179-1-git-send-email-wens@csie.org> <1426732773-7179-2-git-send-email-wens@csie.org> Message-ID: <20150319085716.75d3ce76@i7> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 -- Best regards, Siarhei Siamashka