diff options
authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-06-01 18:09:09 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-01 14:55:01 -0700
commitde95c40d5beaa47f6dc8fe9ac4159b4672b51523 (patch)
parent3425aa03f484d45dc21e0e791c2f6c74ea656421 (diff)
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>
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);