Use polling instead of interrupt + completion to wait until the initial seed was calculated. This should take about 30ms. Call readl_poll_timeout and set the poll interval to the recommended maximum of 20ms. readl_poll_timeout uses usleep_range, this is based on a hrtimer. The task will we put to sleep while waiting, this does not burn CPU cycles by waiting in the foreground. Signed-off-by: Martin Kaiser <martin@xxxxxxxxx> --- v2: - use shorter timeout and polling interval - readl_poll_timeout does not wait in the foreground drivers/char/hw_random/imx-rngc.c | 27 +++++++++------------------ 1 file changed, 9 insertions(+), 18 deletions(-) diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c index c2582673427d..3a3f0f923bed 100644 --- a/drivers/char/hw_random/imx-rngc.c +++ b/drivers/char/hw_random/imx-rngc.c @@ -166,34 +166,29 @@ static irqreturn_t imx_rngc_irq(int irq, void *priv) static int imx_rngc_init(struct hwrng *rng) { struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); - u32 cmd, ctrl; + u32 cmd, ctrl, status, err_reg; int ret; /* clear error */ cmd = readl(rngc->base + RNGC_COMMAND); writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND); - imx_rngc_irq_unmask(rngc); - /* create seed, repeat while there is some statistical error */ do { /* seed creation */ cmd = readl(rngc->base + RNGC_COMMAND); writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND); - ret = wait_for_completion_timeout(&rngc->rng_op_done, - usecs_to_jiffies(RNGC_SEED_TIMEOUT)); - if (!ret) { - ret = -ETIMEDOUT; - goto err; - } + ret = readl_poll_timeout(rngc->base + RNGC_STATUS, status, + status & RNGC_STATUS_SEED_DONE, 20000, RNGC_SEED_TIMEOUT); + if (ret < 0) + return ret; - } while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR); + err_reg = readl(rngc->base + RNGC_ERROR); + } while (err_reg == RNGC_ERROR_STATUS_STAT_ERR); - if (rngc->err_reg) { - ret = -EIO; - goto err; - } + if (err_reg) + return -EIO; /* * enable automatic seeding, the rngc creates a new seed automatically @@ -209,10 +204,6 @@ static int imx_rngc_init(struct hwrng *rng) * we mask the interrupt ourselves if we return an error */ return 0; - -err: - imx_rngc_irq_mask_clear(rngc); - return ret; } static void imx_rngc_cleanup(struct hwrng *rng) -- 2.39.2