On Wed, Mar 15, 2023 at 3:01 PM Tim Harvey tharvey@gateworks.com wrote:
Greetings,
I'm seeing a hang on imx8mm-venice and imx8mn-venice boards which have a USB host controller in host mode when ehci_shutdown() is called (which is called for 'usb stop' as well as when booting a kernel once 'usb start' has been issued).
This appears to be caused by the ehci_shutdown() function, specifically the write to the or_portsc register to set EHCI_PS_SUSP: for (i = 0; i < max_ports; i++) { reg = ehci_readl(&ctrl->hcor->or_portsc[i]); reg |= EHCI_PS_SUSP; ehci_writel(&ctrl->hcor->or_portsc[i], reg); }
Does anyone else out there with an imx8mm/imx8mn board with usbotg1 or usbotg2 configured with dr_mode="host" see this as well?
I'm not clear where the equivalent code would be in the Linux kernel to compare with. I do know that commenting out the ehcI_write above keeps ehci_shutdown from hanging but does cause the handshake to fail on the next cmd that disables CMD_RUN and thus prints "EHCI failed to shut down host controller.".
Any ideas?
Best Regards,
Tim
I haven't heard any response here so I did some more digging. This hang should be affecting all imx8mm/imx8mn devices that have USB host controllers configured for host mode (dr_mode = "host") and would appear for anyone that ever does a 'usb stop' (or does a 'usb start' followed by a kernel boot for example of loading kernel from USB) in U-Boot.
The issue is caused by the pgc_otg{1,2} and/or pgc_hsiomix power domains getting disabled for the 'usb_hub' device (which is present for the USB host even if you have no hub) prior to ehci_shutdown being called.
The following patch resolves this but I'm thinking there should be a better way to control this from ehci-mx6.c?
diff --git a/common/usb_hub.c b/common/usb_hub.c index 85c0822d8b7b..03237deaa0be 100644 --- a/common/usb_hub.c +++ b/common/usb_hub.c @@ -948,7 +948,7 @@ U_BOOT_DRIVER(usb_generic_hub) = { .name = "usb_hub", .id = UCLASS_USB_HUB, .of_match = usb_hub_ids, - .flags = DM_FLAG_ALLOC_PRIV_DMA, + .flags = DM_FLAG_ALLOC_PRIV_DMA | DM_FLAG_LEAVE_PD_ON, };
Best Regards,
Tim