Hello, On Fri, Dec 07, 2018 at 10:57:48AM +0100, Geert Uytterhoeven wrote: > > Is the documentation for this hardware publically available? > > Please check Section 59 of the "User's Manual: Hardware" at > https://www.renesas.com/eu/en/products/microcontrollers-microprocessors/rz/rzg/rzg1m.html Thanks. So the ugly things here are: a) if the pwm is stopped (PWMCR.ENO = 0) the output is set to high after completion of the currently running period. b) setting a duty_cycle of 0 is forbidden both are bad. A workaround for both is implementation of something similar to the switch to a gpio suggested by Michal for imx. But this cannot be done reliably because the current period's end isn't observable. Alternatively a confirmation from the Renesas engineers that PWMCNT.PHO can be set to 0 with the intended effect despite being forbidden in the reference manual would be great. Did someone with access to such hardware test what happens if the PHO field is set to 0? Maybe the forbidden value is just a wrong copy&paste from the CYCO field? I think it would be a good idea to add the link to the documentation into a comment at the top of the driver. @Thierry: Given that nobody seems to have an overview about the features and ugly implementation details of all the PWMs, what about documenting them in the driver files in a greppable way. For the rcar driver something like: - duty-counter-bits: 10 - period-counter-bits: 10 - hardware-polarity-support: false - uglyness: - OUTPUT-ACTIVE-ON-DISABLE - NO-ZERO-DUTY-CYCLE Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
