From: Philipp Tomsich philipp.tomsich@theobroma-systems.com
Throughput tests have shown the sunxi_mmc driver to take over 10s to read 10MB from a fast eMMC device due to excessive delays in polling loops.
This commit restructures the main polling loops to use get_timer(...) to determine whether a (millisecond) timeout has expired. We choose not to use the wait_bit function, as we don't need interruptability with ctrl-c and have at least one case where two bits (one for an error condition and another one for completion) need to be read and using wait_bit would have not added to the clarity.
The observed speedup in testing on a A31 is greater than 10x (e.g. a 10MB write decreases from 9.302s to 0.884s).
Signed-off-by: Philipp Tomsich philipp.tomsich@theobroma-systems.com Signed-off-by: Maxime Ripard maxime.ripard@bootlin.com --- drivers/mmc/sunxi_mmc.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c index 4edb4be46c81..d36c1689e7b1 100644 --- a/drivers/mmc/sunxi_mmc.c +++ b/drivers/mmc/sunxi_mmc.c @@ -187,15 +187,16 @@ static int mmc_update_clk(struct sunxi_mmc_priv *priv) { unsigned int cmd; unsigned timeout_msecs = 2000; + unsigned long start = get_timer(0);
cmd = SUNXI_MMC_CMD_START | SUNXI_MMC_CMD_UPCLK_ONLY | SUNXI_MMC_CMD_WAIT_PRE_OVER; + writel(cmd, &priv->reg->cmd); while (readl(&priv->reg->cmd) & SUNXI_MMC_CMD_START) { - if (!timeout_msecs--) + if (get_timer(start) > timeout_msecs) return -1; - udelay(1000); }
/* clock update sets various irq status bits, clear these */ @@ -276,18 +277,21 @@ static int mmc_trans_data_by_cpu(struct sunxi_mmc_priv *priv, struct mmc *mmc, unsigned i; unsigned *buff = (unsigned int *)(reading ? data->dest : data->src); unsigned byte_cnt = data->blocksize * data->blocks; - unsigned timeout_usecs = (byte_cnt >> 8) * 1000; - if (timeout_usecs < 2000000) - timeout_usecs = 2000000; + unsigned timeout_msecs = byte_cnt >> 8; + unsigned long start; + + if (timeout_msecs < 2000) + timeout_msecs = 2000;
/* Always read / write data through the CPU */ setbits_le32(&priv->reg->gctrl, SUNXI_MMC_GCTRL_ACCESS_BY_AHB);
+ start = get_timer(0); + for (i = 0; i < (byte_cnt >> 2); i++) { while (readl(&priv->reg->status) & status_bit) { - if (!timeout_usecs--) + if (get_timer(start) > timeout_msecs) return -1; - udelay(1); }
if (reading) @@ -303,16 +307,16 @@ static int mmc_rint_wait(struct sunxi_mmc_priv *priv, struct mmc *mmc, uint timeout_msecs, uint done_bit, const char *what) { unsigned int status; + unsigned long start = get_timer(0);
do { status = readl(&priv->reg->rint); - if (!timeout_msecs-- || + if ((get_timer(start) > timeout_msecs) || (status & SUNXI_MMC_RINT_INTERRUPT_ERROR_BIT)) { debug("%s timeout %x\n", what, status & SUNXI_MMC_RINT_INTERRUPT_ERROR_BIT); return -ETIMEDOUT; } - udelay(1000); } while (!(status & done_bit));
return 0; @@ -404,15 +408,16 @@ static int sunxi_mmc_send_cmd_common(struct sunxi_mmc_priv *priv, }
if (cmd->resp_type & MMC_RSP_BUSY) { + unsigned long start = get_timer(0); timeout_msecs = 2000; + do { status = readl(&priv->reg->status); - if (!timeout_msecs--) { + if (get_timer(start) > timeout_msecs) { debug("busy timeout\n"); error = -ETIMEDOUT; goto out; } - udelay(1000); } while (status & SUNXI_MMC_STATUS_CARD_DATA_BUSY); }