On Wed, 2020-07-15 at 00:51 +0000, Peter Chen wrote:

quoted

The Toradex Colibri iMX6ULL board has a special USB hardware design.
With runtime-pm enabled USB reset itself continuously. Furthermore
the OTG port
is also not enumerating devices if the Chipidea IP is in runtime
sleep mode and a
device or host gets plugged in.

Hi Philippe,

You may describe the detail what's the special USB hardware design for
your board,

If I only knew the root-cause of that problem - unfortunately I don't.
That's also why I have such a hard time to describe it.

and why it causes the problem, and why disable runtime pm could fix
this issue, then,

I cannot provide the 'why' part yet. I'll try something more and hope I
can provide you guys with the exact description.

the other users could know if it could apply to their platforms or not
in future.

I only found out about it because you were pointing me in that
direction. I debugged for hours now and didn't came to the root-cause of
the issue. I think to really understand it I would need to know much
more about the Chipidea IP.

I'll get back to you guys with a proposal for a new description.

Philippe

Peter

quoted

This patch adds the opportunity to disable Runtime Power Management
from
devicetree

Signed-off-by: Philippe Schenker <redacted>

---

Changes in v2:
- Change commit message to tell the use case for Colibri iMX6ULL

 drivers/usb/chipidea/ci_hdrc_imx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c

b/drivers/usb/chipidea/ci_hdrc_imx.c
index 5ae16368a0c7..5078d0695eb7 100644

--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c

@@ -434,6 +434,9 @@ static int ci_hdrc_imx_probe(struct

platform_device *pdev)
 		usb_phy_init(pdata.usb_phy);
 	}

+	if (of_property_read_bool(np, "disable-runtime-pm"))
+		pdata.flags &= ~CI_HDRC_SUPPORTS_RUNTIME_PM;
+
 	if (pdata.flags & CI_HDRC_SUPPORTS_RUNTIME_PM)
 		data->supports_runtime_pm = true;

--
2.27.0

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel