Re: [PATCH 70/78] USB: add picdem device to ldusb

On 7/17/07, Greg KH <[email protected]> wrote:
> On Fri, Jul 13, 2007 at 10:20:11PM -0400, Xiaofan Chen wrote:
> >  On 4/27/07, Greg Kroah-Hartman <[email protected]> wrote:
> > > From: Joey Goncalves <[email protected]>
> > >
> > >> Hi Greg:
> > >
> > > >I have found that  /drivers/usb/misc/ldusb.c  works with the "PICDEM Full
> > > > Speed USB"
> > > > http://www.microchip.com/stellent/idcplg?
> > > > IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en021940
> > >
> > >
> > > Signed-off-by: Joey S Goncalves <[email protected]>
> > > Cc: Michael Hund <[email protected]>
> > > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > > ---
> > >  drivers/usb/misc/ldusb.c |    3 +++
> > >  1 files changed, 3 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/drivers/usb/misc/ldusb.c b/drivers/usb/misc/ldusb.c
> > > index 788a11e..11555bd 100644
> > > --- a/drivers/usb/misc/ldusb.c
> > > +++ b/drivers/usb/misc/ldusb.c
> > > @@ -62,6 +62,8 @@
> > >  #define USB_DEVICE_ID_VERNIER_SKIP     0x0003
> > >  #define USB_DEVICE_ID_VERNIER_CYCLOPS  0x0004
> > >
> > > +#define USB_VENDOR_ID_MICROCHIP                0x04d8
> > > +#define USB_DEVICE_ID_PICDEM           0x000c
> > >
> >
> >  PICDEM FS USB is a demo board from Microchip and it
> >  has many examples with different PID.  is one
> >  of the example for the Demo mode.
> >
> >  libusb works very well for the Demo mode (PID=0x000c)
> >  and the boot mode (PID=0x000b).
> >
> >  More info of the libusb based application:
> >
> >  PICDEM FS USB bootloader for Linux/Windows using libusb
> >  http://www.internetking.org/fsusb/
> >  http://forum.microchip.com/tm.aspx?m=106426
> >
> >  PICDEM FS USB demo appliation under Linux/Windows using libusb
> >  http://www.varxec.net/picdem_fs_usb/
> >
> >  Just wondering if there is any benefit of using ldusb compared
> >  to libusb. Sorry I do not know much about ldusb.
>
> ldusb is just a way for devices to use a kernel ring buffer to make sure
> that no data is dropped from the card.  Lots of high-speed devices need
> this.

PICDEM FS USB is based on Microchip 18F4550 MCU which only
support Full Speed.

> >  Will the ldusb driver affect the existing libusb based application?
>
> It might mess them up if the libusb code doesn't try to unbind any
> kernel driver that might be bound to the device already.

I see.

> Can you try running with this patch enabled to see if it handles it
> properly or not?

Right now I am not with my Linux computer to test the code but I
think the current application will fail since they do not have any
kernel driver detaching function. But I can easily patch the code
to add kernel detaching function for Linux. Not a big issue.

> And if libusb is the proper way to talk to this device, then we can
> easily revert this change.
>

I believe that libusb is the right way to do so but I understand it is not
a big issue. Thanks a lot for the explanation.

Regards,
Xiaofan

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