• Geert Uytterhoeven's avatar
    serial: sh-sci: Submit RX DMA from RX interrupt on (H)SCIF · 756981be
    Geert Uytterhoeven authored
    For DMA receive requests, the driver is only notified by DMA completion
    after the whole DMA request has been transferred.  If less data is
    received, it will stay stuck until more data arrives.  The driver
    handles this by setting up a timer handler from the receive interrupt,
    after reception of the first character.
    
    Unlike SCIFA and SCIFB, SCIF and HSCIF don't issue receive interrupts on
    reception of individual characters if a receive DMA request is in
    progress, so the timer is never set up.
    
    To fix receive DMA on SCIF and HSCIF, submit the receive DMA request
    from the receive interrupt handler instead.
    In some sense this is similar to the SCIFA/SCIFB behavior, where the
    RDRQE (Rx Data Transfer Request Enable) bit is also set from the receive
    interrupt handler.
    Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    756981be
sh-sci.c 64.7 KB