On 25/04/2014 16:44, Gregory CLEMENT wrote: > On 25/04/2014 16:15, Thomas Petazzoni wrote: >> Dear Gregory CLEMENT, >> >> On Fri, 25 Apr 2014 16:07:00 +0200, Gregory CLEMENT wrote: >>> Some platform (such as the Armada 38x ones) can gate the clock of >>> their USB controller. This patch add the support for the clock, by >>> enabling them during probe and disabling them on remove. >>> >>> As not all platforms have clock support then enabling and disabling >>> the clocks have been placed in separate functions. Then if the clocks >>> are not supported we still can use the same calls, and there is no >>> >>> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> >>> --- >>> drivers/usb/host/xhci-plat.c | 52 ++++++++++++++++++++++++++++++++++++++++++-- >>> 1 file changed, 50 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c >>> index f5351af4b2c5..bb5d563f729c 100644 >>> --- a/drivers/usb/host/xhci-plat.c >>> +++ b/drivers/usb/host/xhci-plat.c >>> @@ -11,6 +11,7 @@ >>> * version 2 as published by the Free Software Foundation. >>> */ >>> >>> +#include <linux/clk.h> >>> #include <linux/dma-mapping.h> >>> #include <linux/module.h> >>> #include <linux/of.h> >>> @@ -85,6 +86,42 @@ static const struct hc_driver xhci_plat_xhci_driver = { >>> .bus_resume = xhci_bus_resume, >>> }; >>> >>> +#if defined(CONFIG_HAVE_CLK) >>> +static int try_enable_clk(struct platform_device *pdev) >>> +{ >>> + struct clk *clk = devm_clk_get(&pdev->dev, NULL); >>> + >>> + /* Not all platforms have a clk so it is not an error if the clock >>> + does not exists. */ >>> + if (!IS_ERR(clk)) >> >> Instead, do: >> >> if (IS_ERR(clk)) >> return 0; > > As explained in the comment: Not all platforms have a clk so it is not an > error if the clock does not exists. Sorry you were right with the return 0. I misread the value > >> >> return clk_prepare_enable(clk); >> >>> + if (clk_prepare_enable(clk)) >>> + return -ENODEV; >>> + return 0; >>> +} >>> + >>> +static int try_disable_clk(struct platform_device *pdev) >>> +{ >>> + struct clk *clk = devm_clk_get(&pdev->dev, NULL); >> >> No, this isn't correct: you shouldn't be getting the clock to >> disable/unprepare it, otherwise you have an unbalanced number of >> get()/put() calls on the clocks. >> >> Thomas >> > > -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html