Hi,
On 01.03.21 12:07, Ahmad Fatoum wrote:
> Some USB disks take notoriously long to spin up. They are seen by a bus
> scan, but they report ready only after a few seconds have passed. This
> is not a problem if vbus is enabled early on, so devices have had a
> chance to spin up. If vbus is first enabled as part of the usb scan,
> not enough time might have passed for the USB disk to be usable.
>
> This issue was observed on an i.MX6QP with following topology:
>
> usb: USB: scanning bus for devices...
> usb: 5 USB Device(s) found
> 1 ID 0000:0000
> | u-boot EHCI Host Controller
> |
> +-2 ID 0424:2517
> |
> +-5 ID 1058:2621
> | Western Digital Elements 2621
> ...
>
> Unplugging and replugging the USB disk and doing a second usb scan
> made the unit ready test succeed. By increasing the retry count
> during initialization, this workaround is no longer necessary.
Please dismiss for now. This doesn't always work, even for my HDD.
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> drivers/usb/storage/usb.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
> index b417640186a2..7b0aecd757b0 100644
> --- a/drivers/usb/storage/usb.c
> +++ b/drivers/usb/storage/usb.c
> @@ -141,7 +141,7 @@ exit:
> return ret;
> }
>
> -static int usb_stor_test_unit_ready(struct us_blk_dev *usb_blkdev)
> +static int usb_stor_test_unit_ready(struct us_blk_dev *usb_blkdev, int retries)
> {
> u8 cmd[6];
> int ret;
> @@ -150,7 +150,7 @@ static int usb_stor_test_unit_ready(struct us_blk_dev *usb_blkdev)
> cmd[0] = SCSI_TST_U_RDY;
>
> ret = usb_stor_transport(usb_blkdev, cmd, sizeof(cmd), NULL, 0,
> - 10, 100);
> + retries, 100);
> if (ret < 0)
> return -ENODEV;
>
> @@ -282,7 +282,7 @@ static int usb_stor_blk_io(struct block_device *disk_dev,
>
> /* ensure unit ready */
> dev_dbg(dev, "Testing for unit ready\n");
> - if (usb_stor_test_unit_ready(pblk_dev)) {
> + if (usb_stor_test_unit_ready(pblk_dev, 10)) {
> dev_dbg(dev, "Device NOT ready\n");
> return -EIO;
> }
> @@ -365,7 +365,8 @@ static int usb_stor_init_blkdev(struct us_blk_dev *pblk_dev)
> /* ensure unit ready */
> dev_dbg(dev, "Testing for unit ready\n");
>
> - result = usb_stor_test_unit_ready(pblk_dev);
> + /* retry a bit longer than usual as some HDDs take longer to spin up */
> + result = usb_stor_test_unit_ready(pblk_dev, 60);
> if (result) {
> dev_dbg(dev, "Device NOT ready\n");
> return result;
>
--
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