Manual Pages for UNIX Operating System command usage for man usb_get_max_pkts_per_isoc_request

Kernel Functions for Drivers
                            usb_get_max_pkts_per_isoc_request(9F)



NAME
     usb_get_max_pkts_per_isoc_request - Get  maximum  number  of
     packets allowed per isochronous request

SYNOPSIS
     #include 

     uint_t usb_get_max_pkts_per_isoc_request(dev_info_t *dip);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI)

PARAMETERS
     dip    Pointer to the device's dev_info structure.


DESCRIPTION
     The usb_get_max_pkts_per_isoc_request() function returns the
     maximum  number  of isochronous packets per request that the
     host control driver can support. This number can be used  to
     determine the maximum amount of data which can be handled by
     a single isochronous request. That length is found by:

       max = usb_get_max_pkts_per_isoc_request(dip) * endpoint_max_packet_size;



     where endpoint_max_packet_size is the  wMaxPacketSize  field
     of  the  isochronous  endpoint  over which the transfer will
     take place.

RETURN VALUES
     On  success,  the  usb_get_current_frame_number()   function
     returns  the maximum number of isochronous pkts per request.
     On failure it returns 0. The function fails if dip is NULL.

CONTEXT
     May be called from user, kernel or interrupt context.

EXAMPLES
       /*
        * Set up to receive periodic isochronous data, requesting
        * the maximum amount for each transfer.
        */

       int pkt;
       /* Get max packet size from endpoint descriptor. */
       uint_t ep_max_pkt_size = ep_descr.wMaxPacketSize;
       uint_t isoc_pkts_count = usb_get_max_pkts_per_isoc_request(dip);




SunOS 5.11           Last change: 5 Jan 2004                    1






Kernel Functions for Drivers
                            usb_get_max_pkts_per_isoc_request(9F)



       /*
        * Allocate an isoc request, specifying the max number of packets
        * and the greatest size transfer possible.
        */
       usb_isoc_req_t *isoc_req = usb_alloc_isoc_req(dip,
           isoc_pkts_count,
           isoc_pkts_count * ep_max_pkt_size,
           USB_FLAGS_SLEEP);

       /* Init each packet descriptor for maximum size. */
       for (pkt = 0; pkt < isoc_pkts_count; pkt++) {
           isoc_req->isoc_pkt_descr[pkt].isoc_pkt_length = ep_max_pkt_size;

       }


       /* Set the length of a packet in the request too. */
       isoc_req->isoc_pkts_length = ep_max_pkt_size;

       /* Other isoc request initialization. */
       ...
       ...

       if (usb_pipe_isoc_xfer(pipe, isoc_req, USB_FLAGS_NOSLEEP) != USB_SUCCESS) {
           ...
       }


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Architecture                | PCI-based systems           |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | Availability                | driver/usb                  |
    |_____________________________|_____________________________|


SEE ALSO
     attributes(5),                       usb_pipe_isoc_xfer(9F),
     usb_alloc_request(9F),     usb_get_current_frame_number(9F).
     usb_ep_descr(9S), usb_isoc_request(9S)





SunOS 5.11           Last change: 5 Jan 2004                    2






Kernel Functions for Drivers
                            usb_get_max_pkts_per_isoc_request(9F)






















































SunOS 5.11           Last change: 5 Jan 2004                    3