2015-11-18 19:59:14

by Aaro Koskinen

Subject: [PATCH v2] hw_random: omap3-rom-rng: convert timer to delayed work

We cannot put the HW RNG to idle using a timer because we cannot disable
clocks from atomic context. Use a delayed work instead.

Fixes a warning with CONFIG_DEBUG_MUTEXES on Nokia N900 during boot.

Reported-by: Sebastian Reichel <[email protected]>
Signed-off-by: Aaro Koskinen <[email protected]>
---

v2: Include workqueue.h instead of timer.h.

drivers/char/hw_random/omap3-rom-rng.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/char/hw_random/omap3-rom-rng.c b/drivers/char/hw_random/omap3-rom-rng.c
index a405cdc..8da14f1 100644
--- a/drivers/char/hw_random/omap3-rom-rng.c
+++ b/drivers/char/hw_random/omap3-rom-rng.c
@@ -17,7 +17,7 @@
#include <linux/init.h>
#include <linux/random.h>
#include <linux/hw_random.h>
-#include <linux/timer.h>
+#include <linux/workqueue.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/platform_device.h>
@@ -29,11 +29,11 @@
/* param1: ptr, param2: count, param3: flag */
static u32 (*omap3_rom_rng_call)(u32, u32, u32);

-static struct timer_list idle_timer;
+static struct delayed_work idle_work;
static int rng_idle;
static struct clk *rng_clk;

-static void omap3_rom_rng_idle(unsigned long data)
+static void omap3_rom_rng_idle(struct work_struct *work)
{
int r;

@@ -51,7 +51,7 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int count)
u32 r;
u32 ptr;

- del_timer_sync(&idle_timer);
+ cancel_delayed_work_sync(&idle_work);
if (rng_idle) {
clk_prepare_enable(rng_clk);
r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
@@ -65,7 +65,7 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int count)

ptr = virt_to_phys(buf);
r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW);
- mod_timer(&idle_timer, jiffies + msecs_to_jiffies(500));
+ schedule_delayed_work(&idle_work, msecs_to_jiffies(500));
if (r != 0)
return -EINVAL;
return 0;
@@ -102,7 +102,7 @@ static int omap3_rom_rng_probe(struct platform_device *pdev)
return -EINVAL;
}

- setup_timer(&idle_timer, omap3_rom_rng_idle, 0);
+ INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle);
rng_clk = devm_clk_get(&pdev->dev, "ick");
if (IS_ERR(rng_clk)) {
pr_err("unable to get RNG clock\n");
@@ -118,6 +118,7 @@ static int omap3_rom_rng_probe(struct platform_device *pdev)

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);
return 0;
--
2.4.0

2015-11-23 13:05:44

by Herbert Xu

Subject: Re: [PATCH v2] hw_random: omap3-rom-rng: convert timer to delayed work

On Wed, Nov 18, 2015 at 09:59:01PM +0200, Aaro Koskinen wrote:
> We cannot put the HW RNG to idle using a timer because we cannot disable
> clocks from atomic context. Use a delayed work instead.
>
> Fixes a warning with CONFIG_DEBUG_MUTEXES on Nokia N900 during boot.
>
> Reported-by: Sebastian Reichel <[email protected]>
> Signed-off-by: Aaro Koskinen <[email protected]>

Patch applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt