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Subject[PATCH 3/6] hwrng: omap3-rom - Call clk_prepare() on init and exit only
Date
When unloading omap3-rom-rng, we'll get the following:

WARNING: CPU: 0 PID: 100 at drivers/clk/clk.c:948 clk_core_disable

This is because the clock is already disabled by omap3_rom_rng_idle().

Also, we should not call prepare and unprepare except during init, and
only call enable and disable during use.

Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Adam Ford <aford173@gmail.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: Tero Kristo <t-kristo@ti.com>
Fixes: 1c6b7c2108bd ("hwrng: OMAP3 ROM Random Number Generator support")
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
drivers/char/hw_random/omap3-rom-rng.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/char/hw_random/omap3-rom-rng.c b/drivers/char/hw_random/omap3-rom-rng.c
--- a/drivers/char/hw_random/omap3-rom-rng.c
+++ b/drivers/char/hw_random/omap3-rom-rng.c
@@ -44,7 +44,7 @@ static void omap3_rom_rng_idle(struct work_struct *work)
pr_err("reset failed: %d\n", r);
return;
}
- clk_disable_unprepare(rng_clk);
+ clk_disable(rng_clk);
rng_idle = 1;
}

@@ -55,13 +55,13 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int count)

cancel_delayed_work_sync(&idle_work);
if (rng_idle) {
- r = clk_prepare_enable(rng_clk);
+ r = clk_enable(rng_clk);
if (r)
return r;

r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
if (r != 0) {
- clk_disable_unprepare(rng_clk);
+ clk_disable(rng_clk);
pr_err("HW init failed: %d\n", r);
return -EIO;
}
@@ -114,20 +114,32 @@ static int omap3_rom_rng_probe(struct platform_device *pdev)
return PTR_ERR(rng_clk);
}

+ ret = clk_prepare(rng_clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "clk_prepare failed: %i\n", ret);
+ return ret;
+ }
+
/* Leave the RNG in reset state. */
- ret = clk_prepare_enable(rng_clk);
+ ret = clk_enable(rng_clk);
if (ret)
- return ret;
+ goto err_unprepare;
omap3_rom_rng_idle(0);

return hwrng_register(&omap3_rom_rng_ops);
+
+err_unprepare:
+ clk_unprepare(rng_clk);
+
+ return ret;
}

static int omap3_rom_rng_remove(struct platform_device *pdev)
{
cancel_delayed_work_sync(&idle_work);
hwrng_unregister(&omap3_rom_rng_ops);
- clk_disable_unprepare(rng_clk);
+ clk_unprepare(rng_clk);
+
return 0;
}

--
2.23.0
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