Messages in this thread | | | From | Christian Eggers <> | Subject | [PATCH 0/6] clk: imx6*: avoid GPMI clock glitches on reparenting/divider change | Date | Tue, 25 Jan 2022 09:52:00 +0100 |
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On the i.MX6 series (but not on i.MX7/8), most clock multiplexers and switchable dividers are not "glitch safe", so switching them while a consumer is connected can cause glitches with a higher frequency than supported by the consuming peripheral.
Without fixes, peripherals can fail occasionally. One example is that system boot fails due to lockup of the GPMI NAND controller:
f53d4c109a66 ("mtd: rawnand: gpmi: Add ERR007117 protection for nfc_apply_timings")
The conditions where this can appear also depend on the device from which the system is booted and whether the bootloader has already performed all reparenting of the clocks.
To avoid these problems, the clock subsystem must: - Gate consumer clocks during reparenting - Enforce that all consumer clocks are gated before client drivers can change the divider
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