Commit de95c40d authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Greg Kroah-Hartman

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: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3425aa03
...@@ -196,6 +196,9 @@ static int xhci_plat_probe(struct platform_device *pdev) ...@@ -196,6 +196,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
ret = clk_prepare_enable(clk); ret = clk_prepare_enable(clk);
if (ret) if (ret)
goto put_hcd; goto put_hcd;
} else if (PTR_ERR(clk) == -EPROBE_DEFER) {
ret = -EPROBE_DEFER;
goto put_hcd;
} }
xhci = hcd_to_xhci(hcd); xhci = hcd_to_xhci(hcd);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment