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ddi_dma_nextwin (9)
  • >> ddi_dma_nextwin (9) ( Solaris man: Ядро )
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    NAME

    ddi_dma_nextwin - get next DMA window
     
    

    SYNOPSIS

    #include <sys/ddi.h> 
    #include <sys/sunddi.h>
    
    
    
    int ddi_dma_nextwin(ddi_dma_handle_t handle, ddi_dma_win_t win, 
        ddi_dma_win_t *nwin);
    

     

    INTERFACE LEVEL

    This interface is obsolete. ddi_dma_getwin(9F) should be used instead.  

    PARAMETERS

    handle

    A DMA handle.

    win

    The current DMA window or NULL.

    nwin

    A pointer to the next DMA window to be filled in. If win is NULL, a pointer to the first window within the object is returned.

     

    DESCRIPTION

    The ddi_dma_nextwin() function shifts the current DMA window win within the object referred to by handle to the next DMA window nwin. If the current window is NULL, the first window within the object is returned. A DMA window is a portion of a DMA object or might be the entire object. A DMA window has system resources allocated to it and is prepared to accept data transfers. Examples of system resources are DVMA mapping resources and intermediate transfer buffer resources.

    All DMA objects require a window. If the DMA window represents the whole DMA object it has system resources allocated for the entire data transfer. However, if the system is unable to setup the entire DMA object due to system resource limitations, the driver writer may allow the system to allocate system resources for less than the entire DMA object. This can be accomplished by specifying the DDI_DMA_PARTIAL flag as a parameter to ddi_dma_buf_setup(9F) or ddi_dma_addr_setup(9F) or as part of a ddi_dma_req(9S) structure in a call to ddi_dma_setup(9F).

    Only the window that has resources allocated is valid per object at any one time. The currently valid window is the one that was most recently returned from ddi_dma_nextwin(). Furthermore, because a call to ddi_dma_nextwin() will reallocate system resources to the new window, the previous window will become invalid. It is a severe error to call ddi_dma_nextwin() before any transfers into the current window are complete.

    The ddi_dma_nextwin() function takes care of underlying memory synchronizations required to shift the window. However, if you want to access the data before or after moving the window, further synchronizations using ddi_dma_sync(9F) are required.  

    RETURN VALUES

    The ddi_dma_nextwin() function returns:

    DDI_SUCCESS

    Successfully filled in the next window pointer.

    DDI_DMA_DONE

    There is no next window. The current window is the final window within the specified object.

    DDI_DMA_STALE

    win does not refer to the currently active window.

     

    CONTEXT

    The ddi_dma_nextwin() function can be called from user, interrupt, or kernel context.  

    EXAMPLES

    For an example see ddi_dma_segtocookie(9F).  

    ATTRIBUTES

    See attributes(5) for a description of the following attributes:

    ATTRIBUTE TYPEATTRIBUTE VALUE

    Stability LevelObsolete

     

    SEE ALSO

    attributes(5), ddi_dma_addr_setup(9F), ddi_dma_buf_setup(9F), ddi_dma_getwin(9F), ddi_dma_nextseg(9F), ddi_dma_segtocookie(9F), ddi_dma_sync(9F), ddi_dma_req(9S)

    Writing Device Drivers


     

    Index

    NAME
    SYNOPSIS
    INTERFACE LEVEL
    PARAMETERS
    DESCRIPTION
    RETURN VALUES
    CONTEXT
    EXAMPLES
    ATTRIBUTES
    SEE ALSO


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