Hi,
One nitpick..
On Fri, Apr 22, 2016 at 03:16:45PM +0200, Thomas Petazzoni wrote:
> 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.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/usb/host/xhci-plat.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> index 5c15e9b..1a00c9a 100644
> --- a/drivers/usb/host/xhci-plat.c
> +++ b/drivers/usb/host/xhci-plat.c
> @@ -177,6 +177,10 @@ static int xhci_plat_probe(struct platform_device *pdev)
> * clock does not exists.
> */
> clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(clk) && PTR_ERR(clk) == -EPROBE_DEFER) {
> + ret = -EPROBE_DEFER;
> + goto put_hcd;
> + }
> if (!IS_ERR(clk)) {
> ret = clk_prepare_enable(clk);
> if (ret)
if (!IS_ERR(clk)) {
...
} else if (PTR_ERR(clk) == -EPROBE_DEFER)
ret = -EPROBE_DEFER;
goto put_hcd;
...
Cheers,
--
heikki
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