Re: [U-Boot] usb_stor_BBB_transport 5 ms delay - performance

Dear Benoît Thébaudeau,

Hi Jim,

On Thu, Jul 26, 2012 at 10:20:48 PM, Jim Shimer wrote:

...

I'm seeing a 5ms delay in usb_stor_BBB_transport, which occurs every 10K of data for fatload usb or 500ms of delay per 1MB of image size. This adds up to quite a bit of delay if you're loading a large ramdisk.

Does anyone know what the reason for the 5ms delay really is? I'm assuming that this delay is to debounce the 5V/100ma USB power up. I made some modification, where the delay is skipped if the device has already been queried as ready. This has save me 500ms/M on fatload times (eg, 140M=70seconds). Is there anything wrong with this tweak?

Here's a diff of what I've done to get the performance I need:

--- usb_storage.c.orig 2012-07-26 16:06:40.775251000 -0400 +++ usb_storage.c 2012-07-26 13:49:36.000000000 -0400 @@ -132,6 +132,7 @@ static block_dev_desc_t usb_dev_desc[USB

struct us_data; typedef int (*trans_cmnd)(ccb *cb, struct us_data *data); typedef int (*trans_reset)(struct us_data *data);

+typedef enum us_status { USB_NOT_READY, USB_READY} us_status;

struct us_data {

    struct usb_device *pusb_dev;     /* this usb_device */

@@ -154,6 +155,7 @@ struct us_data {

    ccb             *srb;                   /* current srb */
    trans_reset     transport_reset;        /* reset routine */
    trans_cmnd      transport;              /* transport routine
    */

•   us_status       status;
  
  

};

static struct us_data usb_stor[USB_MAX_STOR_DEV];

@@ -691,7 +693,10 @@ int usb_stor_BBB_transport(ccb *srb, str

            usb_stor_BBB_reset(us);
            return USB_STOR_TRANSPORT_FAILED;

    }

•   wait_ms(5);
  

•   if(us->status != USB_READY)
  

•   {
  

•           wait_ms(5);
  

•   }
  
    pipein = usb_rcvbulkpipe(us->pusb_dev, us->ep_in);
    pipeout = usb_sndbulkpipe(us->pusb_dev, us->ep_out);
    /* DATA phase + error handling */
  
  

@@ -957,7 +962,10 @@ static int usb_test_unit_ready(ccb *srb,

            srb->datalen = 0;
            srb->cmdlen = 12;
            if (ss->transport(srb, ss) ==
            USB_STOR_TRANSPORT_GOOD)

•           {
  

•                   ss->status = USB_READY;
  
                    return 0;
  
  

•           }
  
            usb_request_sense(srb, ss);
            wait_ms(100);
  
    } while (retries--);
  
  

@@ -965,6 +973,11 @@ static int usb_test_unit_ready(ccb *srb,

    return -1;

}

+static void usb_set_unit_not_ready(struct us_data *ss) +{

•   ss->status = USB_NOT_READY;
  

+}

static int usb_read_capacity(ccb *srb, struct us_data *ss) {

    int retry;

@@ -1108,6 +1121,7 @@ retry_it: blks -= smallblks; buf_addr += srb->datalen;

    } while (blks != 0);

•   usb_set_unit_not_ready((struct us_data *)dev->privptr);
  
    USB_STOR_PRINTF("usb_read: end startblk %lx, blccnt %x buffer
  
  

%lx\n",

                    start, smallblks, buf_addr);

@@ -1188,6 +1202,7 @@ retry_it: blks -= smallblks; buf_addr += srb->datalen;

    } while (blks != 0);

•   usb_set_unit_not_ready((struct us_data *)dev->privptr);
  
    USB_STOR_PRINTF("usb_write: end startblk %lx, blccnt %x
    buffer
  
  

%lx\n",

                    start, smallblks, buf_addr);

@@ -1398,6 +1413,7 @@ int usb_stor_get_info(struct usb_device

            cap[0] = 2880;
            cap[1] = 0x200;

    }

•   usb_set_unit_not_ready((struct us_data *)dev->privptr);
  
    USB_STOR_PRINTF("Read Capacity returns: 0x%lx, 0x%lx\n",
    cap[0],
  
                    cap[1]);
  
  

#if 0

I'd appreciate any feedback. Regards

I have not looked into this delay issue, but I had similar performance issues that I fixed with the following series: http://patchwork.ozlabs.org/patch/172052/ http://patchwork.ozlabs.org/patch/172204/ http://patchwork.ozlabs.org/patch/172054/ http://patchwork.ozlabs.org/patch/172055/ http://patchwork.ozlabs.org/patch/172056/

Your suggestion is interesting and might be a complement to my series. I don't have time to check its correctness right now, but I'll try soon.

Will you two have time to work these into V2 of your series somehow please?

Best regards, Benoît

Best regards, Marek Vasut