On 01/17, Geert Uytterhoeven wrote:
> INTC-SYS is the module clock for the GIC. Accessing the GIC while it is
> disabled causes:
>
> Unhandled fault: asynchronous external abort (0x1211) at 0x00000000
>
> Currently, the GIC-400 driver cannot enable its module clock for several
> reasons:
> - It does not use a platform device, so Runtime PM is not an option,
> - gic_of_init() runs before any clocks are registered, so it cannot
> enable the clock explicitly,
> - gic_of_init() cannot return -EPROBE_DEFER, as IRQCHIP_DECLARE()
> doesn't support deferred probing.
>
> Hence we have to keep on relying on the boot loader for enabling the
> module clock.
>
> To prevent the module clock from being disabled when the CCF core thinks
> it is unused, and thus causing a system lock-up, add a check to the MSTP
> clock driver and enable CLK_IS_CRITICAL. This will make sure the module
> clock is never disabled.
>
> This is a hard dependency for describing the INTC-SYS clock in DT on
> R-Mobile APE6 and R-Car Gen2.
>
> Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
> ---
Acked-by: Stephen Boyd <sb...@codeaurora.org>
> diff --git a/drivers/clk/renesas/clk-mstp.c b/drivers/clk/renesas/clk-mstp.c
> index 9375777776d99407..c0319b8acf3521a2 100644
> --- a/drivers/clk/renesas/clk-mstp.c
> +++ b/drivers/clk/renesas/clk-mstp.c
> @@ -144,6 +144,11 @@ static int cpg_mstp_clock_is_enabled(struct clk_hw *hw)
Sad that git gets confused about which function this is in.
> init.name = name;
> init.ops = &cpg_mstp_clock_ops;
> init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
> + /* INTC-SYS is the module clock of the GIC, and must not be disabled */
> + if (!strcmp(name, "intc-sys")) {
> + pr_debug("MSTP %s setting CLK_IS_CRITICAL\n", name);
> + init.flags |= CLK_IS_CRITICAL;
> + }
> init.parent_names = &parent_name;
> init.num_parents = 1;
>
--
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