Hello, On Fri, Oct 13, 2023 at 01:13:50PM +0200, Alexander Stein wrote: > Am Freitag, 13. Oktober 2023, 13:04:48 CEST schrieb Stefan Wahren: > > Am 13.10.23 um 12:46 schrieb Sean Young: > > > clk_get_rate() may do a mutex lock. Since the clock rate cannot change on > > > an rpi, simply fetch it once. > > > > does it mean you checked all possible SoCs (BCM2835, BCM2836, BCM2837, > > BCM2711, BCM2712) for this change? > > > > Is it impossible that the real clock can never be influenced by turbo > > mode like SPI? > > Assuming the clock can change, which I would, then a clock notifier seems > appropriate. See [1] for an example. I'm not a fan. If the clock changes, the output also changes. With a clock notifier you can soften the issue and reconfigure to something similar as the original wave form, but a glitch happens for sure. I already toyed with the thought to add clk_rate_exclusive_get() to all PWM drivers, but didn't come around it yet. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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