• Ben Hutchings's avatar
    sfc: Enable RX DMA scattering where possible · 85740cdf
    Ben Hutchings authored
    Enable RX DMA scattering iff an RX buffer large enough for the current
    MTU will not fit into a single page and the NIC supports DMA
    scattering for kernel-mode RX queues.
    
    On Falcon and Siena, the RX_USR_BUF_SIZE field is used as the DMA
    limit for both all RX queues with scatter enabled.  Set it to 1824,
    matching what Onload uses now.
    
    Maintain a statistic for frames truncated due to lack of descriptors
    (rx_nodesc_trunc).  This is distinct from rx_frm_trunc which may be
    incremented when scattering is disabled and implies an over-length
    frame.
    
    Whenever an MTU change causes scattering to be turned on or off,
    update filters that point to the PF queues, but leave others
    unchanged, as VF drivers assume scattering is off.
    
    Add n_frags parameters to various functions, and make them iterate:
    - efx_rx_packet()
    - efx_recycle_rx_buffers()
    - efx_rx_mk_skb()
    - efx_rx_deliver()
    
    Make efx_handle_rx_event() responsible for updating
    efx_rx_queue::removed_count.
    
    Change the RX pipeline state to a starting ring index and number of
    fragments, and make __efx_rx_packet() responsible for clearing it.
    
    Based on earlier versions by David Riddoch and Jon Cooper.
    Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
    85740cdf
efx.h 6.78 KB