From: Kevin Hao <kexin....@windriver.com>
The SDK commit a9d5338d0643 ("hwrng: bcm2835 - sleep more
intelligently") and stable commit 3c5c7f926a4b ("hwrng: bcm2835 - Fix
hwrng throughput regression") are trying to fix the same issue with
different implementation. The later approach is better. So revert
the SDK changes.
Signed-off-by: Kevin Hao <kexin....@windriver.com>
---
Hi Bruce,
Please help me merge this into the following two branches:
v6.1/standard/bcm-2xxx-rpi
v6.1/standard/preempt-rt/bcm-2xxx-rpi
drivers/char/hw_random/bcm2835-rng.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)
diff --git a/drivers/char/hw_random/bcm2835-rng.c
b/drivers/char/hw_random/bcm2835-rng.c
index b821fc12c80d..f46731a5dfe1 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -14,7 +14,6 @@
#include <linux/printk.h>
#include <linux/clk.h>
#include <linux/reset.h>
-#include <linux/delay.h>
#define RNG_CTRL 0x0
#define RNG_STATUS 0x4
@@ -29,9 +28,6 @@
#define RNG_INT_OFF 0x1
-#define RNG_FIFO_WORDS 4
-#define RNG_US_PER_WORD 34 /* Tuned for throughput */
-
struct bcm2835_rng_priv {
struct hwrng rng;
void __iomem *base;
@@ -68,24 +64,19 @@ static inline void rng_writel(struct bcm2835_rng_priv
*priv, u32 val,
static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
- u32 retries = 1000000/(RNG_FIFO_WORDS * RNG_US_PER_WORD);
struct bcm2835_rng_priv *priv = to_rng_priv(rng);
u32 max_words = max / sizeof(u32);
u32 num_words, count;
- num_words = rng_readl(priv, RNG_STATUS) >> 24;
-
- while (!num_words) {
- if (!wait || !retries)
+ while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) {
+ if (!wait)
return 0;
- retries--;
- usleep_range((u32)RNG_US_PER_WORD,
- (u32)RNG_US_PER_WORD * RNG_FIFO_WORDS);
- num_words = rng_readl(priv, RNG_STATUS) >> 24;
hwrng_yield(rng);
}
- num_words = min(num_words, max_words);
+ num_words = rng_readl(priv, RNG_STATUS) >> 24;
+ if (num_words > max_words)
+ num_words = max_words;
for (count = 0; count < num_words; count++)
((u32 *)buf)[count] = rng_readl(priv, RNG_DATA);
--
2.39.2
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