On 2020-09-20 21:01, Stefan Agner wrote:

A JMicron JMS583 based NVMe to USB 3.1 enclosure connected to a Raspberry Pi 4 fails to enumerate as a USB Mass Storage device on first try:

... startig USB... Bus xhci_pci: Register 5000420 NbrPorts 5 Starting the controller USB XHCI 1.00 scanning bus xhci_pci for devces... Device NOT ready Request Sense returned 02 04 01 4 USB Device(s) found scanning usb for storage devices... 0 Sorage Device(s) found

It turned out, the device was not sufficiently powered. Even after I was able to use U-Boot to boot from it, Linux reported USB resets every ~30s or so.

Supplying the device with enough power (e.g. by connecting via powered USB 3.0 Hub) things started to work better: The device was always ready below 1s (8 tries). So it seems that the default of 10 is actually good enough also for this device.

-- Stefan

However, it consistently works on the second try. It seems that the device takes longer than 1s to detect the media. With debug enabled it shows that the 11th retry count typically works.

Increase retries to 20 for a startup time of up to 2s.

Signed-off-by: Stefan Agner stefan@agner.ch

common/usb_storage.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/common/usb_storage.c b/common/usb_storage.c index ff25441995..04910de21f 100644 --- a/common/usb_storage.c +++ b/common/usb_storage.c @@ -1019,7 +1019,7 @@ static int usb_request_sense(struct scsi_cmd *srb, struct us_data *ss)

static int usb_test_unit_ready(struct scsi_cmd *srb, struct us_data *ss) {

• int retries = 10;

• int retries = 20;

  do { memset(&srb->cmd[0], 0, 12);