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[PATCH 3/3] hwrng: st: Use real-world device timings for timeout

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Samples are documented to be available every 0.667us, so in theory
the 8 sample deep FIFO should take 5.336us to fill.  However, during
thorough testing, it became apparent that filling the FIFO actually
takes closer to 12us.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/char/hw_random/st-rng.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
index 44480fe..3b1432c 100644
--- a/drivers/char/hw_random/st-rng.c
+++ b/drivers/char/hw_random/st-rng.c
@@ -33,8 +33,13 @@
 #define ST_RNG_FIFO_DEPTH		8
 #define ST_RNG_FIFO_SIZE		(ST_RNG_FIFO_DEPTH * ST_RNG_SAMPLE_SIZE)
 
-/* Samples are available every 0.667us, which we round to 1us */
-#define ST_RNG_FILL_FIFO_TIMEOUT   (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))
+/*
+ * Samples are documented to be available every 0.667us, so in theory
+ * the 8 sample deep FIFO should take 5.336us to fill.  However, during
+ * thorough testing, it became apparent that filling the FIFO actually
+ * takes closer to 12us.
+ */
+#define ST_RNG_FILL_FIFO_TIMEOUT	12
 
 struct st_rng_data {
 	void __iomem	*base;
-- 
1.9.1

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[RESEND 1/3] hwrng: st: dt: Fix trivial typo in node address Lee Jones <lee.jones@linaro.org> - 2015-10-06 16:50 +0200
  [PATCH 3/3] hwrng: st: Use real-world device timings for timeout Lee Jones <lee.jones@linaro.org> - 2015-10-06 16:50 +0200
    Re: [PATCH 3/3] hwrng: st: Use real-world device timings for timeout Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-06 21:40 +0200
      Re: [PATCH 3/3] hwrng: st: Use real-world device timings for timeout Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-06 23:00 +0200
        Re: [PATCH 3/3] hwrng: st: Use real-world device timings for timeout Lee Jones <lee.jones@linaro.org> - 2015-10-07 10:00 +0200
      Re: [PATCH 3/3] hwrng: st: Use real-world device timings for timeout Lee Jones <lee.jones@linaro.org> - 2015-10-06 23:00 +0200
  Re: [RESEND 1/3] hwrng: st: dt: Fix trivial typo in node address Herbert Xu <herbert@gondor.apana.org.au> - 2015-10-06 17:40 +0200

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