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drivers: net: davinci_mdio: remove busy loop on wait user access 

Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
due to busy loop in wait(). Add small delay to relax cpu.

Signed-off-by: Max Uvarov <muvarov@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Maxim Uvarov 2017-08-10 10:47:46 +03:00 committed by David S. Miller
parent 3a4487b88f
commit 2e1c80847b
1 changed files with 3 additions and 1 deletions
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4
drivers/net/ethernet/ti/davinci_mdio.c
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@ -198,8 +198,10 @@ static inline int wait_for_user_access(struct davinci_mdio_data *data)
return 0;
reg = __raw_readl(&regs->control);
if ((reg & CONTROL_IDLE) == 0)
if ((reg & CONTROL_IDLE) == 0) {
usleep_range(100, 200);
continue;
}
/*
* An emac soft_reset may have clobbered the mdio controller's