Re: [PATCH] clk: meson: axg: mark fdiv2 and fdiv3 as critical

From: Neil Armstrong
Date: Thu Nov 08 2018 - 08:27:06 EST


On 08/11/2018 10:31, Jerome Brunet wrote:
> Similar to gxbb and gxl platforms, axg SCPI Cortex-M co-processor
> uses the fdiv2 and fdiv3 to, among other things, provide the cpu
> clock.
>
> Until clock hand-off mechanism makes its way to CCF and the generic
> SCPI claims platform specific clocks, these clocks must be marked as
> critical to make sure they are never disabled when needed by the
> co-processor.
>
> Fixes: 05f814402d61 ("clk: meson: add fdiv clock gates")
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> ---
>
> Hi Stephen,
>
> If you can put this one in clk-fixes as well, it would be awesome.
> It is basically the same thing as the change you took this Tuesday.
>
> Since then, we had reports the same problem with SCPI was happening
> on the axg, calling for the same fixup.
>
> Cheers
> Jerome
>
> drivers/clk/meson/axg.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/clk/meson/axg.c b/drivers/clk/meson/axg.c
> index c981159b02c0..792735d7e46e 100644
> --- a/drivers/clk/meson/axg.c
> +++ b/drivers/clk/meson/axg.c
> @@ -325,6 +325,7 @@ static struct clk_regmap axg_fclk_div2 = {
> .ops = &clk_regmap_gate_ops,
> .parent_names = (const char *[]){ "fclk_div2_div" },
> .num_parents = 1,
> + .flags = CLK_IS_CRITICAL,
> },
> };
>
> @@ -349,6 +350,18 @@ static struct clk_regmap axg_fclk_div3 = {
> .ops = &clk_regmap_gate_ops,
> .parent_names = (const char *[]){ "fclk_div3_div" },
> .num_parents = 1,
> + /*
> + * FIXME:
> + * This clock, as fdiv2, is used by the SCPI FW and is required
> + * by the platform to operate correctly.
> + * Until the following condition are met, we need this clock to
> + * be marked as critical:
> + * a) The SCPI generic driver claims and enable all the clocks
> + * it needs
> + * b) CCF has a clock hand-off mechanism to make the sure the
> + * clock stays on until the proper driver comes along
> + */
> + .flags = CLK_IS_CRITICAL,
> },
> };
>
>

Acked-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>