On Wed 28 Apr 13:49 CDT 2021, Subbaraman Narayanamurthy wrote: > >> Add PWM driver to support PWM modules inside QCOM PMIC chips which are accessed > >> through SPMI bus. Normally, there would be multiple PWM modules with adjacent > >> address spaces present in one PMIC chip, and each PWM module has 0x100 size of > >> address space. With this driver, a pwm_chip with multiple pwm_device individuals > >> is created, and each pwm_device individual is corresponding to one PWM module. > >> > > > Exposing this as individual pwm_chips will prevent us from enabling the > > LED related use cases (patterns and multicolor) that most versions of > > the hardware support. > > > I proposed [1] a while ago and think this is a better approach. I'll > > take some time to respin this and send out the next version. > > > [1] https://lore.kernel.org/linux-arm-msm/20201021201224.3430546-1-bjorn.andersson@xxxxxxxxxx/ > > Hi Bjorn, > Yes, we came across this patch series but this driver (leds-qcom-lpg) is a > combo one which provides support only for RGB LEDs (or TRI_LED module) along > with PWM/LPG channels allocated for it. Say, if we've additional PWM channels > on the same PMIC (that provides user-interface support) or another PMIC > (non user-interface) that has multiple PWM channels that are not used for LED > notifications, it would be good to have a separate PWM driver to support such > channels IMHO. There are couple of use cases we've come across recently. > > 1. Using a PWM channel for controlling external LCD backlight controller > 2. Using a PWM channel for controlling a haptics actuator > The LPG driver, as it's currently written, support using each channel as a LED, part of a multicolor LED or as a pwm_chip. It's been tested on pm8916 (which doesn't have triled or the lut), pm*8994, pmi8996 and pm8150* in various combinations. In particular the PWM-only modes that you describe here is how the driver has been used on db410c, for driving the "backlight GPIO" in the low-speed connector. Regards, Bjorn
