On 01/10/2017 07:16 AM, Shuah Khan wrote:
> On 01/10/2017 05:05 AM, Bartlomiej Zolnierkiewicz wrote:
>>
>> Hi,
>>
>> On Monday, January 09, 2017 07:21:31 PM Shuah Khan wrote:
>>> Fix dwc3_exynos_probe() to call clk_prepare_enable() only when suspend
>>> clock is specified. Call clk_disable_unprepare() from remove and probe
>>> error path only when susp_clk has been set from remove and probe error
>>> paths.
>>
>> It is legal to call clk_prepare_enable() and clk_disable_unprepare()
>> for NULL clock. Also your patch changes susp_clk handling while
>> leaves axius_clk handling (which also can be NULL) untouched.
>>
>> Do you actually see some runtime problem with the current code?
>>
>> If not then the patch should probably be dropped.
>>
>> Best regards,
>> --
>> Bartlomiej Zolnierkiewicz
>> Samsung R&D Institute Poland
>> Samsung Electronics
>
> Hi Bartlomiej,
>
> I am seeing the "no suspend clk specified" message in dmesg.
> After that it sets the exynos->susp_clk = NULL and starts
> calling clk_prepare_enable(exynos->susp_clk);
>
> That can't be good. If you see the logic right above this
> one for exynos->clk, it returns error and fails the probe.
> This this case it doesn't, but tries to use null susp_clk.
>
> I believe this patch is necessary.
Let me clarify this a bit further. Since we already know
susp_clk is null, with this patch we can avoid extra calls
to clk_prepare_enable() and clk_disable_unprepare().
One can say, it also adds extra checks, hence I will let you
decide one way or the other. :)
thanks,
-- Shuah
>
> thanks,
> -- Shuah
>
>>
>>> Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/usb/dwc3/dwc3-exynos.c | 10 ++++++----
>>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
>>> index e27899b..f97a3d7 100644
>>> --- a/drivers/usb/dwc3/dwc3-exynos.c
>>> +++ b/drivers/usb/dwc3/dwc3-exynos.c
>>> @@ -131,8 +131,8 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>> if (IS_ERR(exynos->susp_clk)) {
>>> dev_info(dev, "no suspend clk specified\n");
>>> exynos->susp_clk = NULL;
>>> - }
>>> - clk_prepare_enable(exynos->susp_clk);
>>> + } else
>>> + clk_prepare_enable(exynos->susp_clk);
>>>
>>> if (of_device_is_compatible(node, "samsung,exynos7-dwusb3")) {
>>> exynos->axius_clk = devm_clk_get(dev, "usbdrd30_axius_clk");
>>> @@ -196,7 +196,8 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>>> regulator_disable(exynos->vdd33);
>>> err2:
>>> clk_disable_unprepare(exynos->axius_clk);
>>> - clk_disable_unprepare(exynos->susp_clk);
>>> + if (exynos->susp_clk)
>>> + clk_disable_unprepare(exynos->susp_clk);
>>> clk_disable_unprepare(exynos->clk);
>>> return ret;
>>> }
>>> @@ -210,7 +211,8 @@ static int dwc3_exynos_remove(struct platform_device *pdev)
>>> platform_device_unregister(exynos->usb3_phy);
>>>
>>> clk_disable_unprepare(exynos->axius_clk);
>>> - clk_disable_unprepare(exynos->susp_clk);
>>> + if (exynos->susp_clk)
>>> + clk_disable_unprepare(exynos->susp_clk);
>>> clk_disable_unprepare(exynos->clk);
>>>
>>> regulator_disable(exynos->vdd33);
>>
>
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