On 25/06/2020 13:09:28+0300, Claudiu Beznea wrote:
> Return in clk_main_osc_prepare()/clk_main_rc_osc_prepare() if
> oscillators are already enabled.
>
> Fixes: 27cb1c2083373 ("clk: at91: rework main clk implementation")
> Fixes: 1bdf02326b71e ("clk: at91: make use of syscon/regmap internally")
Is this really a fix? What is the observed issue?
> Signed-off-by: Claudiu Beznea <[email protected]>
> ---
> drivers/clk/at91/clk-main.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
> index 37c22667e831..46b4d2131989 100644
> --- a/drivers/clk/at91/clk-main.c
> +++ b/drivers/clk/at91/clk-main.c
> @@ -74,13 +74,11 @@ static int clk_main_osc_prepare(struct clk_hw *hw)
> regmap_read(regmap, AT91_CKGR_MOR, &tmp);
> tmp &= ~MOR_KEY_MASK;
>
> - if (tmp & AT91_PMC_OSCBYPASS)
> + if (tmp & (AT91_PMC_OSCBYPASS | AT91_PMC_MOSCEN))
> return 0;
While this seems like a good optimization, it is also not correct.
Having AT91_PMC_MOSCEN set doesn't mean that the clock is ready, you
need to at least check MOSCS once.
>
> - if (!(tmp & AT91_PMC_MOSCEN)) {
> - tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY;
> - regmap_write(regmap, AT91_CKGR_MOR, tmp);
> - }
> + tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY;
> + regmap_write(regmap, AT91_CKGR_MOR, tmp);
>
> while (!clk_main_osc_ready(regmap))
> cpu_relax();
> @@ -186,10 +184,12 @@ static int clk_main_rc_osc_prepare(struct clk_hw *hw)
>
> regmap_read(regmap, AT91_CKGR_MOR, &mor);
>
> - if (!(mor & AT91_PMC_MOSCRCEN))
> - regmap_update_bits(regmap, AT91_CKGR_MOR,
> - MOR_KEY_MASK | AT91_PMC_MOSCRCEN,
> - AT91_PMC_MOSCRCEN | AT91_PMC_KEY);
> + if (mor & AT91_PMC_MOSCRCEN)
> + return 0;
> +
> + regmap_update_bits(regmap, AT91_CKGR_MOR,
> + MOR_KEY_MASK | AT91_PMC_MOSCRCEN,
> + AT91_PMC_MOSCRCEN | AT91_PMC_KEY);
>
> while (!clk_main_rc_osc_ready(regmap))
> cpu_relax();
> --
> 2.7.4
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
