hwrng: omap - Fix RNG wait loop timeout

[sfrench/cifs-2.6.git] / drivers / char / hw_random / omap-rng.c

diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c
index b27f39688b5e71de16650bb7a67c29a54b7539dd..e329f82c0467fffdcbe8c54732089d9735adc95b 100644 (file)
--- 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;