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
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