From 6960f29d4268b622ebc9a3177aecd107f7ae00b5 Mon Sep 17 00:00:00 2001 From: Sumit Garg Date: Mon, 14 Oct 2019 17:32:45 +0530 Subject: [PATCH] hwrng: omap - Fix RNG wait loop timeout Existing RNG data read timeout is 200us but it doesn't cover EIP76 RNG data rate which takes approx. 700us to produce 16 bytes of output data as per testing results. So configure the timeout as 1000us to also take account of lack of udelay()'s reliability. Fixes: d3c2e883a251 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K") Cc: Signed-off-by: Sumit Garg Signed-off-by: Herbert Xu --- drivers/char/hw_random/omap-rng.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c index b27f39688b5e7..e329f82c0467f 100644 --- a/drivers/char/hw_random/omap-rng.c +++ b/drivers/char/hw_random/omap-rng.c @@ -66,6 +66,13 @@ #define OMAP4_RNG_OUTPUT_SIZE 0x8 #define EIP76_RNG_OUTPUT_SIZE 0x10 +/* + * EIP76 RNG takes approx. 700us to produce 16 bytes of output data + * as per testing results. And to account for the lack of udelay()'s + * reliability, we keep the timeout as 1000us. + */ +#define RNG_DATA_FILL_TIMEOUT 100 + enum { RNG_OUTPUT_0_REG = 0, RNG_OUTPUT_1_REG, @@ -176,7 +183,7 @@ static int omap_rng_do_read(struct hwrng *rng, void *data, size_t max, if (max < priv->pdata->data_size) return 0; - for (i = 0; i < 20; i++) { + for (i = 0; i < RNG_DATA_FILL_TIMEOUT; i++) { present = priv->pdata->data_present(priv); if (present || !wait) break; -- 2.39.5