From 0c3f25d8c6aa0ff475a86cd5d3b7e2c7b6eb496f Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Wed, 1 Jun 2016 18:09:09 +0300 Subject: 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: Signed-off-by: Thomas Petazzoni Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/host/xhci-plat.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/usb') 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, -- cgit v1.2.3