#qi-hardware IRC log for Friday, 2015-04-10

viricdoes anybody understand the "Attention" warning in http://en.nanotec.com/products/1023-smci12-stepper-motor-controllers/ ?12:46
whitequarkyes13:38
whitequarkthe power supply apparently has a virtual ground made using two capacitors between line and neutral13:39
whitequarkusually done for EMI reasons which is likely a factor with a stepper controller13:41
viricwhat power supply?13:44
whitequarklaptop13:45
viricso what should I do? Power the board, unplug the laptop from the line, connect the board to the laptop with usb, ...13:58
viricand never connect the laptop to powerline again?13:58
whitequarkwell, it appears this is what they recommend14:01
whitequarkalternatively you can use a line-isolated power supply for either of the laptop and the board14:01
whitequarke.g.: plug it into an isolating transformer, or use a supply that does /not/ have the above connection14:02
whitequark(poke your oscilloscope into GND of the supply and you'll see)14:02
viricwhat should I see in the DC GND of the supply?14:06
whitequarksine with a large amplitude14:30
viricbetween dc gnd and what?14:39
whitequarkand nothing. just put a probe there14:53
viricI don't have an oscilloscope here :)15:00
paul_boddiepcercuei: Looking at pinctrl for jz4740. Lots of repetition between the pinctrl driver and the DTS file. Is that normal?16:01
pcercueipaul_boddie: blame larsc D:16:06
pcercueiI think he's the author16:06
pcercueipaul_boddie: where is this driver? I can't find it16:09
paul_boddieIt's the jz4770 driver I'm adapting. I haven't seen a jz4740 version.16:09
pcercueioh16:09
pcercueidon't use htat16:09
paul_boddieNo, I meant that in the pinctrl, there's a lot of GP?(?) stuff and then in the DTS the GPIOs are defined again.16:09
pcercueiyeah16:09
pcercueidon't use that16:09
pcercueiwe don't even use it anymore16:10
paul_boddieDo you use the jz4780 one, then? The MIPS/Imgtec one?16:10
pcercueiyes16:10
pcercueithe one you're looking at, won't read anything from devicetree16:11
pcercueiwe're using this one now: https://github.com/gcwnow/linux/blob/jz-3.19/drivers/pinctrl/pinctrl-jz4780.c16:11
paul_boddieOK. I saw that, but wondered if it was appropriate.16:11
pcercueiwith this devicetree: https://github.com/gcwnow/linux/blob/jz-3.19/arch/mips/boot/dts/jz4770.dtsi#L6316:12
pcercueiI wrote pinctrl-jz4770, and one week after ImgTec released their set of drivers for the jz478016:12
paul_boddieOK. That might be a better starting point, I guess.16:12
pcercueiI think you could start from MIPS/CI20_Linux16:13
pcercueithey have some improvements to the jz4740 core that is not upstream (and not in the qi-kernel repo either)16:13
paul_boddieI was looking at gcwnow jz-3.18-dts and jz-3.19. The MIPS one didn't seem to be any different.16:14
pcercueilet's say it's getting more and more similar ;)16:14
pcercueithat wasn't really the case a few months ago when they first released the code16:14
pcercueibut we still have some crappy ingenic code in arch/mips/jz477016:16
pcercueifor instance, we don't have real support for DMA or timers16:16
paul_boddieWhat about the upstream jz4740 DMA support?16:17
pcercueiwe use a MMC driver that would scare away any sane kernel developer16:17
pcercueiit's for jz4740; we would need to adapt it to jz477016:17
pcercueithe only difference AFAIK is that we have two DMA chips16:17
pcercueiso 2x 6 channels16:17
paul_boddieHow does one find out the differences? I'm just hoping at the moment that most of the work has already been kind of done. ;-)16:18
pcercueiwhat do you mean?16:18
paul_boddieI'm just thinking about the details like registers, interrupts, and so on.16:19
pcercueiby reading the docs16:19
paul_boddieThe programming manual, I guess.16:20
pcercueiyes16:21
paul_boddieI'll look at MIPS/CI20_Linux ci20-v3.18, then.16:23
paul_boddie(If any of that EOMA-68 hardware gets released with a jz4775 CPU, it'd be nice to see a kernel later than Ingenic's own code-drop version that actually supports it.)16:24
paul_boddieStupid git! Is it normal that git fails when cloning and then leaves no trace of its CPU-thrashing antics?17:05
wpwrakhmm, one for the gnu cpp wish list: #define foo(x) #ifdef x##foo ...22:51
--- Sat Apr 11 201500:00

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