Re: [PATCH 06/13] clk: amlogic: Add noglitch clock driver
From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date: 2026-02-09 21:51:40
Also in:
linux-amlogic, linux-clk, lkml
Hi Chuan Liu, On Mon, Feb 9, 2026 at 6:49 AM Chuan Liu via B4 Relay [off-list ref] wrote: [...]
+ * To prevent glitches from propagating to clk_out and affecting the normal + * operation of glitch-sensitive modules, the no-glitch clock must be configured + * following the specified sequence: + * - When the clock gate is disabled: configure it as a normal composite clock + * (any glitches generated will be blocked by the gate and will not + * propagate to clk_out).
This part is easy and makes sense.
+ * - When the clock gate is enabled: configure it according to the following + * sequence to suppress glitches: + * - Configure and enable the idle composite clock path of the + * noglitch_mux with the target frequency/parent clock. + * - Switch the noglitch_mux to the channel prepared in the previous step. + * - Disable the clock of the original noglitch_mux channel. + */
From a previous discussion it seems that in reality things need to be handled more carefully as you previously mentioned that CLK_SET_RATE_GATE is not good enough (the description above is what CLK_SET_RATE_GATE already achieves). For the more careful handling Jerome suggested using the clock protection logic: [0] You wanted to try it out at some point: [1] Is the verdict that Jerome's suggestion did not work? Can you please share some details as to why it doesn't work. Best regards, Martin [0] https://lore.kernel.org/linux-amlogic/1j1pnp5sg7.fsf@starbuckisacylon.baylibre.com/ (local) [1] https://lore.kernel.org/linux-amlogic/1639bb9d-9cb7-409f-bbf8-bfe4a5d1b8bc@amlogic.com/ (local)