Re: [PATCH v3 3/6] pwm: stm32: add capture support

From: Lee Jones
Date: Mon Apr 16 2018 - 08:24:36 EST


On Fri, 30 Mar 2018, Fabrice Gasnier wrote:

> Add support for PMW input mode on pwm-stm32. STM32 timers support
> period and duty cycle capture as long as they have at least two PWM
> channels. One capture channel is used for period (rising-edge), one
> for duty-cycle (falling-edge).
> When there's only one channel available, only period can be captured.
> Duty-cycle is simply zero'ed in such a case.
>
> Capture requires exclusive access (e.g. no pwm output running at the
> same time, to protect common prescaler).
> Timer DMA burst mode (from MFD core) is being used, to take two
> snapshots of capture registers (upon each period rising edge).
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
> Reviewed-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
> Acked-by: Thierry Reding <thierry.reding@xxxxxxxxx>
> ---
> Changes in v3:
> - update stm32_timers_dma_burst_read() call: don't pass ddata structure,
> use MFD parent device structure instead since MFD core update.
>
> Changes in v2:
> - DMA handling has been moved to MFD core. Rework capture routines to
> use it.
> ---
> drivers/pwm/pwm-stm32.c | 176 +++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/stm32-timers.h | 11 +++

For my own reference:
Acked-for-MFD-by: Lee Jones <lee.jones@xxxxxxxxxx>

> 2 files changed, 187 insertions(+)

--
Lee Jones [æçæ]
Linaro Services Technical Lead
Linaro.org â Open source software for ARM SoCs
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