Re: [PATCH v7 3/4] usb: dwc2: assert phy reset when waking up in rk3288 platform

On 9/6/2016 6:19 PM, Ayaka wrote:

從我的 iPad 傳送

quoted

John Youn [off-list ref] 於 2016年9月7日 上午2:54 寫道：

quoted

On 9/5/2016 10:15 PM, Kishon Vijay Abraham I wrote:
Hi,

quoted

On Sunday 04 September 2016 03:25 AM, Randy Li wrote:
On the rk3288 USB host-only port (the one that's not the OTG-enabled
port) the PHY can get into a bad state when a wakeup is asserted (not
just a wakeup from full system suspend but also a wakeup from
autosuspend).

We can get the PHY out of its bad state by asserting its "port reset",
but unfortunately that seems to assert a reset onto the USB bus so it
could confuse things if we don't actually deenumerate / reenumerate the
device.

We can also get the PHY out of its bad state by fully resetting it using
the reset from the CRU (clock reset unit) in chip, which does a more full
reset.  The CRU-based reset appears to actually cause devices on the bus
to be removed and reinserted, which fixes the problem (albeit in a hacky
way).

It's unfortunate that we need to do a full re-enumeration of devices at
wakeup time, but this is better than alternative of letting the bus get
wedged.

Signed-off-by: Randy Li <ayaka-xPW3/0Ywev/iB9QmIjCX8w@public.gmane.org>
---
drivers/usb/dwc2/core_intr.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index d85c5c9..08485b7 100644
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c

@@ -345,6 +345,7 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)

static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
{
   int ret;
+    struct device_node *np = hsotg->dev->of_node;

   /* Clear interrupt */
   dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);

@@ -379,6 +380,17 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
           /* Restart the Phy Clock */
           pcgcctl &= ~PCGCTL_STOPPCLK;
           dwc2_writel(pcgcctl, hsotg->regs + PCGCTL);
+
+            /*
+             * It is a quirk in Rockchip RK3288, causing by
+             * a hardware bug. This will propagate out and
+             * eventually we'll re-enumerate the device. 
+             * Not great but the best we can do 
+             */
+            if (of_device_is_compatible(np, "rockchip,rk3288-usb")
+                    && (NULL != hsotg->phy->ops->reset))
+                hsotg->phy->ops->reset(hsotg->phy);

never call the phy ops directly from the controller driver. It has to be
protected as well.

It looks like we should be calling an API function instead, correct?

Could you give me a example for the wrapper of phy ops?

Check these files:
* include/linux/phy/phy.h
* drivers/phy/phy-core.c

Search for "phy_set_mode".

I'm thinking there should be a "phy_reset" API function which calls
the phy->ops->reset in a similar manner. With the same runtime checks
and stub function if CONFIG_GENERIC_PHY is not enabled.

Regards,
John
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