I agree with everything, its up to you how to apply the change.
I did see a flags field but thought having a new one was conservative (I
had no real reason to have a new field). As for the typecasts I was
following the API which tests for device ready (Monkey See Monkey Do).
Also I have no compelling reason to need a "setter function" either. I
have no compelling feelings towards the implementation other than the 5ms
adds an unnecessary delay when the device is already known to be ready, and
this delay accumulates to a very poor performance for large files.
Thanks for working on this!
On Fri, Jul 27, 2012 at 11:06 AM, Marek Vasut <ma...@denx.de> wrote:
> 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;
>
> Can we possibly avoid the typedef?
>
> > > 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;
>
> Don't we have some flags for it already?
>
> > >
> > > };
> > >
> > > 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;
> > > +}
> > > +
>
> We don't need a setter function really.
>
> > > 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);
>
> I think we should be much more careful about these typecasts.
>
> > > 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);
>
> Same here.
>
> > > 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);
>
> The rest is cool.
> [...]
>
--
*James H Shimer*
Motorola Mobility T3-12-HH72
900 Chelmsford Street
Lowell MA 08151
978-614-3550
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