From mboxrd@z Thu Jan 1 00:00:00 1970 From: wens@csie.org (Chen-Yu Tsai) Date: Thu, 26 Mar 2015 10:56:00 -0700 Subject: [linux-sunxi] Re: [PATCH 1/2] ARM: dts: sun4i: a10-lime: Override and remove 1008MHz OPP setting In-Reply-To: <55143ACF.9070800@gmail.com> References: <1426732773-7179-1-git-send-email-wens@csie.org> <1426732773-7179-2-git-send-email-wens@csie.org> <20150319085716.75d3ce76@i7> <55143ACF.9070800@gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Thu, Mar 26, 2015 at 9:58 AM, Iain Paton wrote: > On 19/03/15 06:57, Siarhei Siamashka wrote: > >> 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. > > I'm somewhat sad to see 1008MHz go. I have 2x revA A10-Lime boards that > are stable at 1008MHz with Maximes sunxi/for-next, a full regulator > description in the dts and a very recent u-boot. They are not stable at > 1056 or above however. > > > Can I ask what the basis is for the 960MHz setting? I don't see any > instances of it in any of the a10 fex files, meaning it's likely not > very well tested. It was copied from the wrong file. Please see v2 of the series. > If there's interest, I'll send the patch adding regulators to the dts for > the a10-lime. Please do. ChenYu