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author | Thomas Petazzoni <thomas.petazzoni@free-electrons.com> | 2016-06-01 18:09:09 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-06-01 14:55:01 -0700 |
commit | de95c40d5beaa47f6dc8fe9ac4159b4672b51523 (patch) | |
tree | 3c726385f1d387c017002c34cf2f6392f8f3b738 /drivers/usb | |
parent | 3425aa03f484d45dc21e0e791c2f6c74ea656421 (diff) | |
download | op-kernel-dev-de95c40d5beaa47f6dc8fe9ac4159b4672b51523.zip op-kernel-dev-de95c40d5beaa47f6dc8fe9ac4159b4672b51523.tar.gz |
usb: xhci-plat: properly handle probe deferral for devm_clk_get()
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>
Diffstat (limited to 'drivers/usb')
-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 676ea45..1f3f981 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -196,6 +196,9 @@ 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; } xhci = hcd_to_xhci(hcd); |