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.
What about to incorporate it to this patch?
@@ -354,16 +354,25 @@ static void utmi_phy_clk_disable(struct tegra_usb_phy *phy)
pr_err("%s: timeout waiting for phy to stabilize\n", __func__);
}
static void utmi_phy_clk_enable(struct tegra_usb_phy *phy)
{
unsigned long val;
void __iomem *base = phy->regs;
+ /*
+ * The USB driver may have already initiated the phy clock
+ * enable so wait to see if the clock turns on and if not
+ * then proceed with ungating the clock.
+ */
+ if (utmi_wait_register(base + USB_SUSP_CTRL, USB_PHY_CLK_VALID,
+ USB_PHY_CLK_VALID) == 0)
+ return;
+
if (phy->is_legacy_phy) {
val = readl(base + USB_SUSP_CTRL);
val |= USB_SUSP_CLR;
writel(val, base + USB_SUSP_CTRL);
udelay(10);
val = readl(base + USB_SUSP_CTRL);
--
Dmitry
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