On Tue, Feb 27, 2018 at 08:27:14PM -0600, Samuel Holland wrote:
> +	/*
> +	 * The failure path should not disable the clock or assert the reset,
> +	 * because the PSCI implementation in firmware relies on this device
> +	 * being functional. Claiming the clock in this driver is required to
> +	 * prevent Linux from turning it off.
> +	 */
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable bus clock: %d\n", ret);
> +		return ret;
> +	}

You don't need it to be always on though. You only need it to be
enabled when you access the registers (on both sides I guess?). So you
could very well enable the clock in your registers accessors in Linux,
and do the same in the ARISC firmware. That should work.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com