mmc: tmio: Fixup runtime PM management during probe

The tmio_mmc_host_probe() calls pm_runtime_set_active() to update the
runtime PM status of the device, as to make it reflect the current status
of the HW. This works fine for most cases, but unfortunate not for all.
Especially, there is a generic problem when the device has a genpd attached
and that genpd have the ->start|stop() callbacks assigned.

More precisely, if the driver calls pm_runtime_set_active() during
->probe(), genpd does not get to invoke the ->start() callback for it,
which means the HW isn't really fully powered on. Furthermore, in the next
phase, when the device becomes runtime suspended, genpd will invoke the
->stop() callback for it, potentially leading to usage count imbalance
problems, depending on what's implemented behind the callbacks of course.

To fix this problem, convert to call pm_runtime_get_sync() from
tmio_mmc_host_probe() rather than pm_runtime_set_active(). Additionally, to
avoid bumping usage counters and unnecessary re-initializing the HW the
first time the tmio driver's ->runtime_resume() callback is called,
introduce a state flag to keeping track of this.

Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index c5ba13fae39920e656de9737412804e2f5155a77..2f0b092d6dcc64d199b75ec7563600f1954502dd 100644 (file)
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -163,6 +163,7 @@ struct tmio_mmc_host {
        unsigned long           last_req_ts;
        struct mutex            ios_lock;       /* protect set_ios() context */
        bool                    native_hotplug;
+       bool                    runtime_synced;
        bool                    sdio_irq_enabled;
 
        /* Mandatory callback */

diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index 8b299c1f0069306cd55aa5056ff0455186ff12d1..32f9679ec42ec97364faa81bce027a8b7ba204aa 100644 (file)
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -1248,20 +1248,22 @@ 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);
        pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_enable(&pdev->dev);
+       pm_runtime_get_sync(&pdev->dev);
 
        ret = mmc_add_host(mmc);
        if (ret)
                goto remove_host;
 
        dev_pm_qos_expose_latency_limit(&pdev->dev, 100);
+       pm_runtime_put(&pdev->dev);
 
        return 0;
 
 remove_host:
+       pm_runtime_put_noidle(&pdev->dev);
        tmio_mmc_host_remove(_host);
        return ret;
 }
@@ -1330,6 +1332,11 @@ int tmio_mmc_host_runtime_resume(struct device *dev)
 {
        struct tmio_mmc_host *host = dev_get_drvdata(dev);
 
+       if (!host->runtime_synced) {
+               host->runtime_synced = true;
+               return 0;
+       }
+
        tmio_mmc_clk_enable(host);
        tmio_mmc_hw_reset(host->mmc);