mmc: core: fix performance regression initializing MMC host controllers
Commit fa5501890d8974301042e0202d342a6cbe8609f4 introduced a performance
regression by adding mmc_power_up() to mmc_start_host(). mmc_power_up()
is not necessary to host controller initialization, it is part of card
initialization and is performed anyway asynchronously.
This patch allows a driver to leave the power up in asynchronous code
(as it was before).
On my current target platform this reduces driver initialization from:
[ 1.313220] initcall sdhci_acpi_driver_init+0x0/0x12 returned 0 after 102008 usecs
to this:
[ 1.217209] initcall sdhci_acpi_driver_init+0x0/0x12 returned 0 after 8331 usecs
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 2592ddd..7bcf74b 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -195,6 +195,8 @@
host->mmc->pm_caps |= c->slot->pm_caps;
}
+ host->mmc->caps2 |= MMC_CAP2_NO_PRESCAN_POWERUP;
+
err = sdhci_add_host(host);
if (err)
goto err_free;