[PATCH v2 1/2] mmc: tmio: leave clock handling to runtime PM if enabled

[Ulrich Hecht <uli+renesas@fpond.eu>]

This fixes a clock imbalance that occurs on Renesas systems because the SD
clock is handled by both runtime PM and the hardware driver. After a
suspend/resume cycle both enable the same clock, resulting in an enable
count of 2 even if the clock is only used by one device.

See https://www.spinics.net/lists/linux-mmc/msg44431.html for details.

This patch removes the clock handling from the driver's runtime PM
callbacks and turns the clock off after probing if the device has a power
domain attached.

Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ulrich Hecht <uli+renesas@fpond.eu>
Tested-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
---
 drivers/mmc/host/tmio_mmc_core.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index 31ffcc3..733ff96 100644
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -1260,9 +1260,14 @@ int tmio_mmc_host_probe(struct tmio_mmc_host *_host)
 	/* See if we also get DMA */
 	tmio_mmc_request_dma(_host, pdata);
 
-	pm_runtime_set_active(&pdev->dev);
+#ifdef CONFIG_PM
+	/* PM handles the clock; disable it so it won't be enabled twice. */
+	if (_host->clk_disable && pdev->dev.pm_domain)
+		_host->clk_disable(_host);
+	pm_runtime_get_sync(&pdev->dev);
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
 	pm_runtime_use_autosuspend(&pdev->dev);
+#endif
 
 	ret = mmc_add_host(mmc);
 	if (ret)
@@ -1325,7 +1330,8 @@ int tmio_mmc_host_runtime_suspend(struct device *dev)
 	if (host->clk_cache)
 		host->set_clock(host, 0);
 
-	tmio_mmc_clk_disable(host);
+	if (!dev->pm_domain)
+		tmio_mmc_clk_disable(host);
 
 	return 0;
 }
@@ -1340,7 +1346,9 @@ int tmio_mmc_host_runtime_resume(struct device *dev)
 {
 	struct tmio_mmc_host *host = dev_get_drvdata(dev);
 
-	tmio_mmc_clk_enable(host);
+	if (!dev->pm_domain)
+		tmio_mmc_clk_enable(host);
+
 	tmio_mmc_hw_reset(host->mmc);
 
 	if (host->clk_cache)
-- 
2.7.4