On Sat, Mar 06, 2021 at 09:15:27AM +0100, Stefan Roese wrote:
On 05.03.21 21:03, Phil Sutter wrote:
With the recent fixes in pci_mvebu and xhci-pci drivers, the two rear USB3 ports are finally usable and accessing them no longer hangs the system. Moreover, if Linux is booted without a prior call to 'pci enum' and 'usb start', the HCD is detected but attached devices are not usable:
| xhci_hcd 0000:02:00.0: xHCI Host Controller | xhci_hcd 0000:02:00.0: new USB bus registered, assigned bus number 2 | xhci_hcd 0000:02:00.0: hcc params 0x040040a5 hci version 0x100 quirks 0x0000000000080490 | usb usb2: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04 | usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1 | usb usb2: Product: xHCI Host Controller | usb usb2: Manufacturer: Linux 5.4.92-1 xhci-hcd | usb usb2: SerialNumber: 0000:02:00.0 | hub 2-0:1.0: USB hub found | ata1: SATA link down (SStatus 0 SControl 300) | hub 2-0:1.0: 2 ports detected | xhci_hcd 0000:02:00.0: xHCI Host Controller | xhci_hcd 0000:02:00.0: new USB bus registered, assigned bus number 3 | xhci_hcd 0000:02:00.0: Host supports USB 3.0 SuperSpeed | usb usb3: We don't know the algorithms for LPM for this host, disabling LPM. | usb usb3: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 5.04 | usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1 | usb usb3: Product: xHCI Host Controller | usb usb3: Manufacturer: Linux 5.4.92-1 xhci-hcd | usb usb3: SerialNumber: 0000:02:00.0 | hub 3-0:1.0: USB hub found | hub 3-0:1.0: 2 ports detected [...] | xhci_hcd 0000:02:00.0: Error while assigning device slot ID | xhci_hcd 0000:02:00.0: Max number of devices this xHCI host supports is 64. | usb usb2-port2: couldn't allocate usb_device
To avoid this problem, enumerate PCI (and USB) from PREBOOT.
Signed-off-by: Phil Sutter phil@nwl.cc
Changes since v1:
- Have to enable XHCI_HCD as well to fulfill Kconfig dependency.
- Explicitly disable XHCI_MARVELL which defaults to enabled.
- Prefix PREBOOT with 'pci enum'.
- Update commit message accordingly.
Hmmm, in general is should not be necessary to configure / setup any of the devices in the bootloader so that it works correctly in Linux. It's best practice, that Linux does not rely on any bootloader setup. If a device, like PCI and/or USB does not work in Linux without this U-Boot setup, then it should be fixed in Linux instead.
Especially calling "usb start" adds a quite big delay to the bootup time. I would really like to not add such changes. Perhaps you could check with the maintainer(s) of the Linux PCI driver and/or the USB PCI controller driver about this issue instead?
Turns out I should have tried a more recent kernel first, the bug I was working around is quite certainly fixed by Linux commit 216f8e95aacc8 ("PCI: mvebu: Setup BAR0 in order to fix MSI").
I'll send a v3 without the fuss but with the Kconfig fix.
Sorry for the noise,
Phil