• Baruch Siach's avatar
    enc28j60: reduce the number of spi transfers in enc28j60_set_bank() · 5664dd55
    Baruch Siach authored
    
    
    A major source of overhead in the enc28j60 driver is the SPI transfers. Each
    SPI transfer entails two kernel thread context switches. One major source of
    SPI transfers is the enc28j60_set_bank() functions which runs before every
    register access. This patch reduces the number of SPI transfers that
    enc28j60_set_bank() performs in two ways:
    
      1. removes unnecessary bank switch for the registers that are present in all
    	 banks
    
      2. when switching from banks 0 or 3 to banks 1 or 2 (i.e. only one bit
    	 changes) enc28j60_set_bank() does only one SPI transfer instead of two
    
    According to my tests these changes reduce the number of SPI transfers in
    about 25%.
    Signed-off-by: default avatarBaruch Siach <baruch@tkos.co.il>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    5664dd55