@@ -2416,7 +2416,8 @@ void mmc_start_host(struct mmc_host *host)
{
host->f_init = max(freqs[0], host->f_min);
host->rescan_disable = 0;
- mmc_power_up(host);
+ if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP))
+ mmc_power_up(host);
mmc_detect_change(host, 0);
}
@@ -195,6 +195,8 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
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;
@@ -280,6 +280,7 @@ struct mmc_host {
#define MMC_CAP2_PACKED_WR (1 << 13) /* Allow packed write */
#define MMC_CAP2_PACKED_CMD (MMC_CAP2_PACKED_RD | \
MMC_CAP2_PACKED_WR)
+#define MMC_CAP2_NO_PRESCAN_POWERUP (1 << 14) /* Don't power up before scan */
mmc_pm_flag_t pm_caps; /* supported pm features */
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. Please see the original commit for an explanation of the use of mmc_power_up() in mmc_start_host(). 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> --- drivers/mmc/core/core.c | 3 ++- drivers/mmc/host/sdhci-acpi.c | 2 ++ include/linux/mmc/host.h | 1 + 3 files changed, 5 insertions(+), 1 deletion(-)