mmc: sdhci-pxav3: fix unbalanced clock issues during probe
authorJisheng Zhang <jszhang@marvell.com>
Sun, 4 Jan 2015 15:15:47 +0000 (23:15 +0800)
committerUlf Hansson <ulf.hansson@linaro.org>
Mon, 19 Jan 2015 08:56:31 +0000 (09:56 +0100)
commit62cf983ad84275f8580c807e5e596216c46773cf
tree574a4849322e2d746f7057e4eddb54c5e2270a30
parent250fb7b45031fd56f5f54da27ffc6fe05abea98e
mmc: sdhci-pxav3: fix unbalanced clock issues during probe

Commit 0dcaa2499b7d ("sdhci-pxav3: Fix runtime PM initialization") tries
to fix one hang issue caused by calling sdhci_add_host() on a suspended
device. The fix enables the clock twice, once by clk_prepare_enable() and
another by pm_runtime_get_sync(), meaning that the clock will never be
gated at runtime PM suspend. I observed the power consumption regression on
Marvell BG2Q SoCs.

In fact, the fix is not correct. There still be a very small window
during which a runtime suspend might somehow occur after pm_runtime_enable()
but before pm_runtime_get_sync().

This patch fixes all of the two problems by just incrementing the usage
counter before pm_runtime_enable(). It also adjust the order of disabling
runtime pm and storing the usage count in the error path to handle clock
gating properly.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Cc: <stable@vger.kernel.org> # v3.11+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
drivers/mmc/host/sdhci-pxav3.c