mmc: core: fix performance regression initializing MMC host controllers (0d3e3350) · Commits · 戴 / test

Commit 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>

drivers/mmc/core/core.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2416,6 +2416,7 @@ void mmc_start_host(struct mmc_host *host)
		{
		host->f_init = max(freqs[0], host->f_min);
		host->rescan_disable = 0;
		if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP))
		mmc_power_up(host);
		mmc_detect_change(host, 0);
		}

drivers/mmc/host/sdhci-acpi.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

include/linux/mmc/host.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 */

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