A-Team_Digital_Solutions/android_kernel_motorola_sm6375
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mmc: core: fix performance regression initializing MMC host controllers

Browse source 
Commit fa5501890d 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 <[email protected]>
Acked-by: Ulf Hansson <[email protected]>
Signed-off-by: Chris Ball <[email protected]>
This commit is contained in:
Adrian Hunter 2013-04-04 16:41:06 +03:00 • committed by Chris Ball
commit 0d3e3350d5
3 changed files with 5 additions and 1 deletions
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3
drivers/mmc/core/core.c
View file

@ -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);
}

2
drivers/mmc/host/sdhci-acpi.c
View file

@ -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;