In message: [linux-yocto] Revert "hwrng: bcm2835 - sleep more intelligently"
on 04/12/2023 Kevin Hao wrote:
> 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
merged.
Bruce
>
> 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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