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i2c: mv64xxx: handle probe deferral for the clock

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If a clock is registered by a platform driver and not by the
OF_CLK_DECLARE() mechanism, it might show up after the first attempt
to probe i2c-mv64xxx. In order to solve this, we need to handle
-EPROBE_PREFER as a special return value of devm_clk_get(), and return
the same error code from probe().

This gives us three situations:

 - There is no reference to a clock in the DT. In this case,
   devm_clk_get() returns an error that is not -EPROBE_DEFER
   (something like -ENODEV), and we continue the probing without
   enabling the clock.

 - There is a reference to the clock in the DT, and the clock is
   ready. devm_clk_get() returns a valid reference to the clock, and
   we prepare/enable it.

 - There is a reference to the clock in the DT, but the clock is not
   ready. devm_clk_get() returns -EPROBE_DEFER, and we exit from
   probe() with the same error code so that probe() is tried again
   later.

This is needed for Marvell Armada 7K/8K, where the clock driver is a
platform driver.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Thomas Petazzoni 2016-04-22 15:19:52 +02:00 committed by Wolfram Sang
parent 05872b8039
commit 9f4d6f1642
1 changed files with 2 additions and 0 deletions
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2
drivers/i2c/busses/i2c-mv64xxx.c
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@ -910,6 +910,8 @@ mv64xxx_i2c_probe(struct platform_device *pd)
#if defined(CONFIG_HAVE_CLK)
/* Not all platforms have a clk */
drv_data->clk = devm_clk_get(&pd->dev, NULL);
if (IS_ERR(drv_data->clk) && PTR_ERR(drv_data->clk) == -EPROBE_DEFER)
return -EPROBE_DEFER;
if (!IS_ERR(drv_data->clk)) {
clk_prepare(drv_data->clk);
clk_enable(drv_data->clk);