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Subject[PATCH v3 1/4] net: macb: Check MDIO state before read/write and use timeouts
Date
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 <harini.katakam@xilinx.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
v3 changes:
Used MACB_BIT for IDLE field

v2 changes:
Use readx_poll_timeout

Changes form RFC:
Cleaned up timeout implementation and moved it to a helper.

drivers/net/ethernet/cadence/macb.h | 2 ++
drivers/net/ethernet/cadence/macb_main.c | 33 ++++++++++++++++++++++++++------
2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 9bbaad9..f51040f 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -715,6 +715,8 @@
__v; \
})

+#define MACB_READ_NSR(bp) macb_readl(bp, NSR)
+
/* struct macb_dma_desc - Hardware DMA descriptor
* @addr: DMA address of data buffer
* @ctrl: Control and status bits
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index f2915f2..a19ed2b 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -36,6 +36,7 @@
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/tcp.h>
+#include <linux/iopoll.h>
#include "macb.h"

#define MACB_RX_BUFFER_SIZE 128
@@ -79,6 +80,8 @@
*/
#define MACB_HALT_TIMEOUT 1230

+#define MACB_MDIO_TIMEOUT 1000000 /* in usecs */
+
/* DMA buffer descriptor might be different size
* depends on hardware configuration:
*
@@ -318,10 +321,23 @@ static void macb_get_hwaddr(struct macb *bp)
eth_hw_addr_random(bp->dev);
}

+static int macb_mdio_wait_for_idle(struct macb *bp)
+{
+ u32 val;
+
+ return readx_poll_timeout(MACB_READ_NSR, bp, val, val & MACB_BIT(IDLE),
+ 1, MACB_MDIO_TIMEOUT);
+}
+
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 +345,9 @@ 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 +358,11 @@ 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 +371,9 @@ 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
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