Re: [PATCH 2/2] clk: at91: main: do not continue if oscillators already prepared
From: Alexandre Belloni <alexandre.belloni@bootlin.com>
Date: 2020-06-26 21:04:02
Also in:
linux-clk, lkml
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?
quoted hunk ↗ jump to hunk
Signed-off-by: Claudiu Beznea <redacted> --- 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.
quoted hunk ↗ jump to hunk
- 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel