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

Neil Armstrong
2018-11-14T02:40:05Z

Le 13/11/2018 17:38, Neil Armstrong a ï¿½crit :
> 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 ?

I forgot, but it should also go into the next 4.19 stable release aswell.

Neil

> 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,
>> },
>> };
>>
>>