Le 24 sept. 2018 07:35, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> a écrit : > > On 24/09/2018 07:24, Paul Cercueil wrote: > > Hi Daniel, > > > > Le 24 sept. 2018 05:12, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> a écrit : > >> > >> On 21/08/2018 19:16, Paul Cercueil wrote: > >>> This driver handles the TCU (Timer Counter Unit) present on the Ingenic > >>> JZ47xx SoCs, and provides the kernel with a system timer, and optionally > >>> with a clocksource and a sched_clock. > >>> > >>> It also provides clocks and interrupt handling to client drivers. > >> > >> Can you provide a much more complete description of the timer in order > >> to make my life easier for the review of this patch? > > > > See patch [03/24], it adds a doc file that describes the hardware. > > Thanks, I went through but it is incomplete to understand what the timer > do. I will reverse-engineer the code but it would help if you can give > the gross approach. Why multiple channels ? mutexes and completion ? Much of the complexity is because of the multi-purpose nature of the TCU channels. Each one can be used as timer/clocksource, or PWM. The driver starts by using channels 0 and 1 as system timer and clocksource, respectively, the other ones being unused for now. Then, *if* the PWM driver requests one of the channels in use by the timer/clocksource driver, say channel 0, the timer/clocksource driver will dynamically reassign the system timer to a free channel, from channel 0 to e.g. channel 2. Only in that case the completion/mutex are actually used. -Paul
