From eadb7897652d5bf9fbab393b3774598a04846aff Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Fri, 8 May 2020 11:52:10 +0200 Subject: [PATCH] mmc: sdricoh_cs: Throttle polling rate for data transfers Rather than to poll in a busy-loop, let's convert into using read_poll_timeout() and insert a small delay between each polling attempts. In particular, this avoids hogging the CPU. Additionally, to convert to read_poll_timeout() we also need to switch from using a specific number of polling attempts, into a specific timeout in us instead. The previous 100000 attempts, is translated into a total timeout of total 1s, as that seemed like reasonable value to pick. Cc: Sascha Sommer Signed-off-by: Ulf Hansson Link: https://lore.kernel.org/r/20200508095210.14123-1-ulf.hansson@linaro.org --- drivers/mmc/host/sdricoh_cs.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/drivers/mmc/host/sdricoh_cs.c b/drivers/mmc/host/sdricoh_cs.c index 97ef7d7..8392158 100644 --- a/drivers/mmc/host/sdricoh_cs.c +++ b/drivers/mmc/host/sdricoh_cs.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -59,7 +60,7 @@ static unsigned int switchlocked; /* timeouts */ #define CMD_TIMEOUT 100000 -#define TRANSFER_TIMEOUT 100000 +#define SDRICOH_DATA_TIMEOUT_US 1000000 /* list of supported pcmcia devices */ static const struct pcmcia_device_id pcmcia_ids[] = { @@ -123,21 +124,24 @@ static inline unsigned int sdricoh_readb(struct sdricoh_host *host, return value; } +static bool sdricoh_status_ok(struct sdricoh_host *host, unsigned int status, + unsigned int wanted) +{ + sdricoh_writel(host, R2E4_STATUS_RESP, status); + return status & wanted; +} + static int sdricoh_query_status(struct sdricoh_host *host, unsigned int wanted) { - unsigned int loop; + int ret; unsigned int status = 0; - unsigned int timeout = TRANSFER_TIMEOUT; struct device *dev = host->dev; - for (loop = 0; loop < timeout; loop++) { - status = sdricoh_readl(host, R21C_STATUS); - sdricoh_writel(host, R2E4_STATUS_RESP, status); - if (status & wanted) - break; - } - - if (loop == timeout) { + ret = read_poll_timeout(sdricoh_readl, status, + sdricoh_status_ok(host, status, wanted), + 32, SDRICOH_DATA_TIMEOUT_US, false, + host, R21C_STATUS); + if (ret) { dev_err(dev, "query_status: timeout waiting for %x\n", wanted); return -ETIMEDOUT; } -- 2.7.4