| Message ID | 20190913220922.29501-4-tony@atomide.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Non-urgent fixes and improvments for omap3-rom-rng | expand |
Hi, On Fri, Sep 13, 2019 at 03:09:19PM -0700, Tony Lindgren wrote: > Also, we should not call prepare and unprepare except during init, and > only call enable and disable during use. Why? Usually clk_(un)prepare() is the part saving most power, so I would expect the runtime resume handlers to call clk_prepare_enable and vice versa in the suspend handler. -- Sebastian
* Sebastian Reichel <sre@kernel.org> [190914 13:01]: > Hi, > > On Fri, Sep 13, 2019 at 03:09:19PM -0700, Tony Lindgren wrote: > > Also, we should not call prepare and unprepare except during init, and > > only call enable and disable during use. > > Why? Usually clk_(un)prepare() is the part saving most power, so I > would expect the runtime resume handlers to call clk_prepare_enable > and vice versa in the suspend handler. Sure yeah fine with me, clk_prepare_enable() is more generic at the cost of some extra calls to toggle a clock gate bit :) Let's also forget the probe changes, those will get cleared with the runtime PM changes anyways. Regards, Tony
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; }
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(-)