[PATCH 1/4] net: macb: Check MDIO state before read/write and use timeouts

Harini Katakam
2018-10-31T03:40:56Z

From: Harini Katakam <harinik@xilinx.com>

Replace the while loop in MDIO read/write functions with a timeout.
In addition, add a check for MDIO bus busy before initiating a new
operation as well to make sure there is no ongoing MDIO operation.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Signed-off-by: Harini Katakam <harinik@xilinx.com>
---
Changes form RFC:
Cleaned up timeout implementation and moved it to a helper.

drivers/net/ethernet/cadence/macb_main.c | 44 +++++++++++++++++++++++++++-----
1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 0acaef3..b4e26c1 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -318,10 +318,36 @@ static void macb_get_hwaddr(struct macb *bp)
eth_hw_addr_random(bp->dev);
}

+static int macb_mdio_wait_for_idle(struct macb *bp)
+{
+ ulong timeout;
+
+ timeout = jiffies + msecs_to_jiffies(1000);
+ /* wait for end of transfer */
+ while (1) {
+ if (MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
+ break;
+
+ if (time_after_eq(jiffies, timeout)) {
+ netdev_err(bp->dev, "wait for end of transfer timed out\n");
+ return -ETIMEDOUT;
+ }
+
+ cpu_relax();
+ }
+
+ return 0;
+}
+
static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
{
struct macb *bp = bus->priv;
int value;
+ int err;
+
+ err = macb_mdio_wait_for_idle(bp);
+ if (err < 0)
+ return err;

macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_SOF)
| MACB_BF(RW, MACB_MAN_READ)
@@ -329,9 +355,9 @@ static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
| MACB_BF(REGA, regnum)
| MACB_BF(CODE, MACB_MAN_CODE)));

- /* wait for end of transfer */
- while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
- cpu_relax();
+ err = macb_mdio_wait_for_idle(bp);
+ if (err < 0)
+ return err;

value = MACB_BFEXT(DATA, macb_readl(bp, MAN));

@@ -342,6 +368,12 @@ static int macb_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
u16 value)
{
struct macb *bp = bus->priv;
+ int err;
+
+
+ err = macb_mdio_wait_for_idle(bp);
+ if (err < 0)
+ return err;

macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_SOF)
| MACB_BF(RW, MACB_MAN_WRITE)
@@ -350,9 +382,9 @@ static int macb_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
| MACB_BF(CODE, MACB_MAN_CODE)
| MACB_BF(DATA, value)));

- /* wait for end of transfer */
- while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
- cpu_relax();
+ err = macb_mdio_wait_for_idle(bp);
+ if (err < 0)
+ return err;

return 0;
}
--
2.7.4