diff options
| author | Thomas Petazzoni <thomas.petazzoni@free-electrons.com> | 2016-06-01 18:09:09 +0300 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-07-10 20:19:52 -0400 |
| commit | 0c3f25d8c6aa0ff475a86cd5d3b7e2c7b6eb496f (patch) | |
| tree | aefbf15290e057c157a4b537cd253d8c60efd1c0 | |
| parent | e78c8a575fd956a4e8a04125c50c23264e012e8e (diff) | |
usb: xhci-plat: properly handle probe deferral for devm_clk_get()
[ Upstream commit de95c40d5beaa47f6dc8fe9ac4159b4672b51523 ]
On some platforms, the clocks might be registered by a platform
driver. When this is the case, the clock platform driver may very well
be probed after xhci-plat, in which case the first probe() invocation
of xhci-plat will receive -EPROBE_DEFER as the return value of
devm_clk_get().
The current code handles that as a normal error, and simply assumes
that this means that the system doesn't have a clock for the XHCI
controller, and continues probing without calling
clk_prepare_enable(). Unfortunately, this doesn't work on systems
where the XHCI controller does have a clock, but that clock is
provided by another platform driver. In order to fix this situation,
we handle the -EPROBE_DEFER error condition specially, and abort the
XHCI controller probe(). It will be retried later automatically, the
clock will be available, devm_clk_get() will succeed, and the probe()
will continue with the clock prepared and enabled as expected.
In practice, such issue is seen on the ARM64 Marvell 7K/8K platform,
where the clocks are registered by a platform driver.
Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | drivers/usb/host/xhci-plat.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c index 783e819139a7..7606710baf43 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -116,6 +116,9 @@ static int xhci_plat_probe(struct platform_device *pdev) ret = clk_prepare_enable(clk); if (ret) goto put_hcd; + } else if (PTR_ERR(clk) == -EPROBE_DEFER) { + ret = -EPROBE_DEFER; + goto put_hcd; } if (of_device_is_compatible(pdev->dev.of_node, |