2017-05-30 16:51 GMT+02:00 Ralph Sennhauser <ralph.sennhauser@xxxxxxxxx>: > On Tue, 30 May 2017 15:40:00 +0200 > Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> wrote: > >> Hi Ralph and Linus, >> >> I resurrect this thread following the series post by Richard Genoud: >> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-May/509461.html >> >> On lun., avril 24 2017, Linus Walleij <linus.walleij@xxxxxxxxxx> >> wrote: >> >> > On Fri, Apr 14, 2017 at 5:40 PM, Ralph Sennhauser >> > <ralph.sennhauser@xxxxxxxxx> wrote: >> > >> >> From: Andrew Lunn <andrew@xxxxxxx> >> >> >> >> Armada 370/XP devices can 'blink' GPIO lines with a configurable on >> >> and off period. This can be modelled as a PWM. >> >> >> >> However, there are only two sets of PWM configuration registers for >> >> all the GPIO lines. This driver simply allows a single GPIO line >> >> per GPIO chip of 32 lines to be used as a PWM. Attempts to use >> >> more return EBUSY. >> >> >> >> Due to the interleaving of registers it is not simple to separate >> >> the PWM driver from the GPIO driver. Thus the GPIO driver has been >> >> extended with a PWM driver. >> >> >> >> Signed-off-by: Andrew Lunn <andrew@xxxxxxx> >> >> URL: https://patchwork.ozlabs.org/patch/427287/ >> >> URL: https://patchwork.ozlabs.org/patch/427295/ >> >> [Ralph Sennhauser: >> >> * Port forward >> >> * Merge PWM portion into gpio-mvebu.c >> >> * Switch to atomic PWM API >> >> * Add new compatible string marvell,armada-370-xp-gpio >> >> The fact that Richard managed to run the code on Armada 38x draw my >> attention on the documentation that need to be amend. > > Hi Gregory > > But does it behave as a pwm-fan? I don't have access to the 38x > functional spec (no NDA with Marvell), the one for XP is public. > According to Andrew the 38x doesn't have the blinking hardware and so I > expect the pwm-fan is just an overblown gpio-fan there, additionally > writing some random values to random registers where luck has it nothing > goes wrong. > > Kirkwood apparently has blinking support but only at fixed frequency of > 10Hz, so not usable for this purpose either. > > So to my knowledge it really is just 370 and XP. Hi Ralph, I have the functional spec (no NDA needed, but it's not the full one) : A38x-Functional-Spec-PU0A.pdf https://marvellcorp.wufoo.com/forms/marvell-armada-38x-functional-specifications/ (just an email needed, no blood signing nor chicken slaughtering) There are the GPIO Blink Counter A/B is ON/OFF Duration Registers as well as the Blink Enable Registers. I've done a pwm with different periods (8ms, 4ms, 100ns). Looking at the scope, it seems to work pretty well :) >> >> And it makes me realized that I missed the bad naming of the >> compatible string. We don't use family name for the compatible >> string, but the name of the first SoC compatible with. So in this >> case we should use "marvell,armada-370", as it is still in rc and not >> yet deployed. What about fixing the name now? > > I don't mind but certainly not for me to decide at this point. > >> >> I can send a patch for it if you want and fix the dts that are still >> in my mvebu branch. > > Sure, or if you prefer I can do it as well if we decide for the change. > No preference. > > Ralph -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
