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net: phy: mscc-miim: improve waiting logic 

The MSCC MIIM MDIO driver uses a waiting logic to wait for the MDIO bus
to be ready to accept next commands. It does so by polling the BUSY
status bit which indicates the MDIO bus has completed all pending
operations. This can take time, and the controller supports writing the
next command as soon as there are no pending commands (which happens
while the MDIO bus is busy completing its current command).

This patch implements this improved logic by adding an helper to poll
the PENDING status bit, and by adjusting where we should wait for the
bus to not be busy or to not be pending.

Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
alistair/sunxi64-5.8
Antoine Tenart 2020-05-26 18:22:55 +02:00 committed by David S. Miller
parent f5112c8ae2
commit d9c6de35e0
1 changed files with 13 additions and 2 deletions
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15
drivers/net/phy/mdio-mscc-miim.c
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@ -16,6 +16,7 @@
#include <linux/of_mdio.h>
#define MSCC_MIIM_REG_STATUS 0x0
#define MSCC_MIIM_STATUS_STAT_PENDING BIT(2)
#define MSCC_MIIM_STATUS_STAT_BUSY BIT(3)
#define MSCC_MIIM_REG_CMD 0x8
#define MSCC_MIIM_CMD_OPR_WRITE BIT(1)
@ -47,13 +48,23 @@ static int mscc_miim_wait_ready(struct mii_bus *bus)
!(val & MSCC_MIIM_STATUS_STAT_BUSY), 50, 10000);
}
static int mscc_miim_wait_pending(struct mii_bus *bus)
{
struct mscc_miim_dev *miim = bus->priv;
u32 val;
return readl_poll_timeout(miim->regs + MSCC_MIIM_REG_STATUS, val,
!(val & MSCC_MIIM_STATUS_STAT_PENDING),
50, 10000);
}
static int mscc_miim_read(struct mii_bus *bus, int mii_id, int regnum)
{
struct mscc_miim_dev *miim = bus->priv;
u32 val;
int ret;
ret = mscc_miim_wait_ready(bus);
ret = mscc_miim_wait_pending(bus);
if (ret)
goto out;
@ -82,7 +93,7 @@ static int mscc_miim_write(struct mii_bus *bus, int mii_id,
struct mscc_miim_dev *miim = bus->priv;
int ret;
ret = mscc_miim_wait_ready(bus);
ret = mscc_miim_wait_pending(bus);
if (ret < 0)
goto out;