[PATCH 5.2 30/85] mmc: tmio: Fixup runtime PM management during probe

Greg Kroah-Hartman
2019-09-18T06:25:22Z

From: Ulf Hansson <ulf.hansson@linaro.org>

commit aa86f1a3887523d78bfadd1c4e4df8f919336511 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/host/tmio_mmc.h | 1 +
drivers/mmc/host/tmio_mmc_core.c | 9 ++++++++-
2 files changed, 9 insertions(+), 1 deletion(-)

--- 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 */
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -1258,20 +1258,22 @@ int tmio_mmc_host_probe(struct tmio_mmc_
/* 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;
}
@@ -1340,6 +1342,11 @@ int tmio_mmc_host_runtime_resume(struct
{
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);