Re: [PATCH v2] clk: meson-gxbb: set fclk_div3 as CLK_IS_CRITICAL

Neil Armstrong
2018-11-13T16:38:29Z

Hi Stable team,

Le 06/11/2018 00:08, Jerome Brunet a ï¿½crit :
> From: Christian Hewitt <christianshewitt@gmail.com>
>
> On the Khadas VIM2 (GXM) and LePotato (GXL) board there are problems
> with reboot; e.g. a ~60 second delay between issuing reboot and the
> board power cycling (and in some OS configurations reboot will fail
> and require manual power cycling).
>
> Similar to 'commit c987ac6f1f088663b6dad39281071aeb31d450a8 ("clk:
> meson-gxbb: set fclk_div2 as CLK_IS_CRITICAL")' the SCPI Cortex-M4
> Co-Processor seems to depend on FCLK_DIV3 being operational.
>
> Until commit 05f814402d6174369b3b29832cbb5eb5ed287059 ("clk:
> meson: add fdiv clock gates"), this clock was modeled and left on by
> the bootloader.
>
> We don't have precise documentation about the SCPI Co-Processor and
> its clock requirement so we are learning things the hard way.
>
> Marking this clock as critical solves the problem but it should not
> be viewed as final solution. Ideally, the SCPI driver should claim
> these clocks. We also depends on some clock hand-off mechanism
> making its way to CCF, to make sure the clock stays on between its
> registration and the SCPI driver probe.
>
> Fixes: 05f814402d61 ("clk: meson: add fdiv clock gates")
> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Could this patch go into the next 4.18 stable release since it hit linus master with commit id e2576c8bdfd462c34b8a46c0084e7c30b0851bf4 ?

Thanks,
Neil

> ---
> drivers/clk/meson/gxbb.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/clk/meson/gxbb.c b/drivers/clk/meson/gxbb.c
> index 9309cfaaa464..4ada9668fd49 100644
> --- a/drivers/clk/meson/gxbb.c
> +++ b/drivers/clk/meson/gxbb.c
> @@ -506,6 +506,18 @@ static struct clk_regmap gxbb_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,
> },
> };
>
>