[PATCH mvebu v2 06/10] clk: mvebu: armada-37xx-periph: Fix workaround for switching from L1 to L0

[Stephen Boyd]

Quoting Pali Rohár (2021-01-14 04:40:28)
> When CPU frequency is at 250 MHz and set_rate() is called with 500 MHz (L1)
> quickly followed by a call with 1 GHz (L0), the CPU does not necessarily
> stay in L1 for at least 20ms as is required by Marvell errata.
> 
> This situation happens frequently with the ondemand cpufreq governor and
> can be also reproduced with userspace governor. In most cases it causes CPU
> to crash.
> 
> This change fixes the above issue and ensures that the CPU always stays in
> L1 for at least 20ms when switching from any state to L0.
> 
> Signed-off-by: Marek Behún <kabel at kernel.org>
> Signed-off-by: Pali Rohár <pali at kernel.org>
> Fixes: 61c40f35f5cd ("clk: mvebu: armada-37xx-periph: Fix switching CPU rate from 300Mhz to 1.2GHz")
> Cc: stable at vger.kernel.org
> ---

Acked-by: Stephen Boyd <sboyd at kernel.org>