From: Thomas Petazzoni Date: Wed, 1 Jun 2016 15:09:09 +0000 (+0300) Subject: usb: xhci-plat: properly handle probe deferral for devm_clk_get() X-Git-Tag: v4.14-rc1~3008^2~43 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=de95c40d5beaa47f6dc8fe9ac4159b4672b51523;p=platform%2Fkernel%2Flinux-rpi.git 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: Signed-off-by: Thomas Petazzoni Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman --- 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);