[RFT PATCH v1 4/5] usb: Provide code to handle spinup of USB usb devices (mostly HDDs)

[Marek Vasut]

On 3/22/20 2:00 PM, Lukasz Majewski wrote:
[...]
> diff --git a/common/usb_storage.c b/common/usb_storage.c
> index 92e1e54d1c..3c2324fa1a 100644
> --- a/common/usb_storage.c
> +++ b/common/usb_storage.c
> @@ -729,6 +729,7 @@ static int usb_stor_BBB_transport(struct scsi_cmd *srb, struct us_data *us)
>  	pipeout = usb_sndbulkpipe(us->pusb_dev, us->ep_out);
>  	/* DATA phase + error handling */
>  	data_actlen = 0;
> +	mdelay(10);		/* Like linux does. */

Does this add delay to every single transfer ?
That would mean a massive slowdown if you use short data transfers,
which is needed for old/limited USB sticks.

>  	/* no data, go immediately to the STATUS phase */
>  	if (srb->datalen == 0)
>  		goto st;
> @@ -1023,9 +1024,32 @@ static int usb_request_sense(struct scsi_cmd *srb, struct us_data *ss)
>  	return 0;
>  }
>  
> +/*
> + * This spins up the disk and also consumes the time that the
> + * disk takes to become active and ready to read data.
> + * Some drives (like Western Digital) can take more than 5 seconds.
> + * The delay occurs on the 1st data read from the disk.
> + * Extending the timeout here works better than handling the timeout
> + * as an error on a "real" read.
> + */
> +static int usb_spinup(struct scsi_cmd *srb, struct us_data *ss)
> +{
> +	memset(&srb->cmd[0], 0, 12);
> +	srb->cmd[0] = SCSI_START_STP;
> +	srb->cmd[1] = srb->lun << 5;
> +	srb->cmd[4] = 1;	/* Start spinup. */
> +	srb->datalen = 0;
> +	srb->cmdlen = 6;
> +	ss->pusb_dev->extra_timeout = 9876;

What is this magic number ?

> +	ss->transport(srb, ss);
> +	ss->pusb_dev->extra_timeout = 0;
> +	return 0;
> +}

[...]

> diff --git a/include/usb.h b/include/usb.h
> index efb67ea33f..5b0f5ce5d6 100644
> --- a/include/usb.h
> +++ b/include/usb.h
> @@ -140,6 +140,7 @@ struct usb_device {
>  	int act_len;			/* transferred bytes */
>  	int maxchild;			/* Number of ports if hub */
>  	int portnr;			/* Port number, 1=first */
> +	int extra_timeout; /* Add to timeout in ehci_submit_async or spinup */

Does this work with xhci too ?