On 29.09.2017 17:57, Dmitry Osipenko wrote:
> On 29.09.2017 16:10, Jon Hunter wrote:
>> Adding Dmitry ...
>>
>> Felipe, Thierry, this is needed for v4.14-rc because suspend is currently
>> broken for some Tegra devices.
>>
>> Jon
>>
>> On 29/09/17 14:06, Jon Hunter wrote:
>>> Commit dfebb5f43a78 ("usb: chipidea: Add support for Tegra20/30/114/124")
>>> added UDC support for Tegra but with UDC support enabled, is was found
>>> that Tegra30, Tegra114 and Tegra124 would hang on entry to suspend.
>>>
>>> The hang occurred during the suspend of the USB PHY when the Tegra PHY
>>> driver attempted to disable the PHY clock. The problem is that before
>>> the Tegra PHY driver is suspended, the chipidea driver already disabled
>>> the PHY clock and when the Tegra PHY driver suspended, it could not read
>>> DEVLC register and caused the device to hang.
>>>
>>> The Tegra USB PHY driver is used by both the Tegra EHCI driver and now
>>> the chipidea UDC driver and so simply removing the disabling of the PHY
>>> clock from the USB PHY driver would not work for the Tegra EHCI driver.
>>> Fortunately, the status of the USB PHY clock can be read from the
>>> USB_SUSP_CTRL register and therefore, to workaround this issue, simply
>>> poll the register prior to disabling the clock in USB PHY driver to see
>>> if clock gating has already been initiated. Please note that it can take
>>> a few uS for the clock to disable and so simply reading this status
>>> register once on entry is not sufficient.
>>>
>>> Please note that no issues are seen with Tegra20 because it has a slightly
>>> different PHY to Tegra30/114/124.
>>>
>>
>> I forgot the fixes tag ...
>>
>> Fixes: dfebb5f43a78 ("usb: chipidea: Add support for Tegra20/30/114/124")
>>
>>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
>>> ---
>>> drivers/usb/phy/phy-tegra-usb.c | 8 ++++++++
>>> 1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
>>> index 5fe4a5704bde..c8fff99bd16e 100644
>>> --- a/drivers/usb/phy/phy-tegra-usb.c
>>> +++ b/drivers/usb/phy/phy-tegra-usb.c
>>> @@ -329,6 +329,14 @@ static void utmi_phy_clk_disable(struct tegra_usb_phy *phy)
>>> unsigned long val;
>>> void __iomem *base = phy->regs;
>>>
>>> + /*
>>> + * The USB driver may have already initiated the phy clock
>>> + * disable so wait to see if the clock turns off and if not
>>> + * then proceed with gating the clock.
>>> + */
>>> + if (utmi_wait_register(base + USB_SUSP_CTRL, USB_PHY_CLK_VALID, 0) == 0)
>>> + return;
>>> +
>>> if (phy->is_legacy_phy) {
>>> val = readl(base + USB_SUSP_CTRL);
>>> val |= USB_SUSP_SET;
>>>
>>
>
> Adding analogical check to clk_enable fixes "utmi_phy_clk_enable: timeout
> waiting for phy to stabilize" error message during of kernel boot-up on Tegra20.
>
'During of UDC probe' would me more correct to say and UDC driver still working
excellent.
--
Dmitry
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