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Date: Tue, 6 Oct 2015 17:12:50 +0100 From: Lee Jones <lee.jones@...aro.org> To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: kernel@...inux.com, herbert@...dor.apana.org.au, linux-crypto@...r.kernel.org, peter@...sgaard.com, festevam@...il.com, pankaj.dev@...com, daniel.thompson@...aro.org, Lee Jones <lee.jones@...aro.org> Subject: [RESEND 2/3] hwrng: st: Use real-world device timings for timeout 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@...aro.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 8c8a435..a1ff080 100644 --- a/drivers/char/hw_random/st-rng.c +++ b/drivers/char/hw_random/st-rng.c @@ -32,8 +32,13 @@ #define ST_RNG_FIFO_SIZE 8 #define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */ -/* 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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