On 27.06.2020 00:03, Alexandre Belloni wrote:

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On 25/06/2020 13:09:28+0300, Claudiu Beznea wrote:

quoted

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

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.

I agree! This is may introduce issues. Thank you for reviewing it.

quoted

-     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

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