net/smsc911x: Fix delays in the PHY enable/disable routines
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: Alexander Kochetkov <al.kochet@gmail.com>
Acked-by: Steve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed