• Alexander Kochetkov's avatar
    net/smsc911x: Fix delays in the PHY enable/disable routines · 6ff53fd3
    Alexander Kochetkov authored
    Increased delay in the smsc911x_phy_disable_energy_detect (from 1ms to 2ms).
    Dropped delays in the smsc911x_phy_enable_energy_detect (100ms and 1ms).
    
    The patch affect SMSC LAN generation 4 chips with integrated PHY (LAN9221).
    
    I saw problems with soft reset due to wrong udelay timings.
    After I fixed udelay, I measured the time needed to bring integrated PHY
    from power-down to operational mode (the time beetween clearing EDPWRDOWN
    bit and soft reset complete event). I got 1ms (measured using ktime_get).
    The value is equal to the current value (1ms) used in the
    smsc911x_phy_disable_energy_detect. It is near the upper bound and in order
    to avoid rare soft reset faults it is doubled (2ms).
    
    I don't know official timing for bringing up integrated PHY as specs doesn't
    clarify this (or may be I didn't found).
    
    It looks safe to drop delays before and after setting EDPWRDOWN bit
    (enable PHY power-down mode). I didn't saw any regressions with the patch.
    
    The patch was reviewed by Steve Glendinning and Microchip Team.
    Signed-off-by: default avatarAlexander Kochetkov <al.kochet@gmail.com>
    Acked-by: default avatarSteve Glendinning <steve.glendinning@shawell.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    6ff53fd3
smsc911x.c 68.6 KB