* [PATCH] net: memac_phy: add a timeout to MDIO operations
@ 2020-12-09 11:31 Ioana Ciornei
2020-12-09 13:04 ` Madalin Bucur
0 siblings, 1 reply; 2+ messages in thread
From: Ioana Ciornei @ 2020-12-09 11:31 UTC (permalink / raw)
To: u-boot
We have encountered circumstances when a board design does not include
pull-up resistors on the external MDIO buses which are not used. This
leads to the MDIO data line not being pulled-up, thus the MDIO controller
will always see the line as busy.
Without a timeout in the MDIO bus driver, the execution is stuck in an
infinite loop when any access is initiated on that external bus.
Add a timeout in the driver so that we are protected in this
circumstance. This is similar to what is being done in the Linux
xgmac_mdio driver.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
---
drivers/net/fm/memac_phy.c | 76 +++++++++++++++++++++++++++++---------
1 file changed, 58 insertions(+), 18 deletions(-)
diff --git a/drivers/net/fm/memac_phy.c b/drivers/net/fm/memac_phy.c
index c2ef1b4e737e..b92a012ce79f 100644
--- a/drivers/net/fm/memac_phy.c
+++ b/drivers/net/fm/memac_phy.c
@@ -22,6 +22,8 @@
#define memac_setbits_32(a, v) setbits_be32(a, v)
#endif
+#define MAX_NUM_RETRIES 1000
+
static u32 memac_in_32(u32 *reg)
{
#ifdef CONFIG_SYS_MEMAC_LITTLE_ENDIAN
@@ -31,6 +33,42 @@ static u32 memac_in_32(u32 *reg)
#endif
}
+/*
+ * Wait until the MDIO bus is free
+ */
+static int memac_wait_until_free(struct memac_mdio_controller *regs)
+{
+ unsigned int timeout = MAX_NUM_RETRIES;
+
+ while ((memac_in_32(®s->mdio_stat) & MDIO_STAT_BSY) && timeout--)
+ ;
+
+ if (!timeout) {
+ printf("timeout waiting for MDIO bus to be free\n");
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
+/*
+ * Wait till the MDIO read or write operation is complete
+ */
+static int memac_wait_until_done(struct memac_mdio_controller *regs)
+{
+ unsigned int timeout = MAX_NUM_RETRIES;
+
+ while ((memac_in_32(®s->mdio_data) & MDIO_DATA_BSY) && timeout--)
+ ;
+
+ if (!timeout) {
+ printf("timeout waiting for MDIO operation to complete\n");
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
/*
* Write value to the PHY for this device to the register at regnum, waiting
* until the write is done before it returns. All PHY configuration has to be
@@ -42,6 +80,7 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
u32 mdio_ctl;
struct memac_mdio_controller *regs = bus->priv;
u32 c45 = 1; /* Default to 10G interface */
+ int err;
if (dev_addr == MDIO_DEVAD_NONE) {
c45 = 0; /* clause 22 */
@@ -50,9 +89,9 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
} else
memac_setbits_32(®s->mdio_stat, MDIO_STAT_ENC);
- /* Wait till the bus is free */
- while ((memac_in_32(®s->mdio_stat)) & MDIO_STAT_BSY)
- ;
+ err = memac_wait_until_free(regs);
+ if (err)
+ return err;
/* Set the port and dev addr */
mdio_ctl = MDIO_CTL_PORT_ADDR(port_addr) | MDIO_CTL_DEV_ADDR(dev_addr);
@@ -62,16 +101,16 @@ int memac_mdio_write(struct mii_dev *bus, int port_addr, int dev_addr,
if (c45)
memac_out_32(®s->mdio_addr, regnum & 0xffff);
- /* Wait till the bus is free */
- while ((memac_in_32(®s->mdio_stat)) & MDIO_STAT_BSY)
- ;
+ err = memac_wait_until_free(regs);
+ if (err)
+ return err;
/* Write the value to the register */
memac_out_32(®s->mdio_data, MDIO_DATA(value));
- /* Wait till the MDIO write is complete */
- while ((memac_in_32(®s->mdio_data)) & MDIO_DATA_BSY)
- ;
+ err = memac_wait_until_done(regs);
+ if (err)
+ return err;
return 0;
}
@@ -87,6 +126,7 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
u32 mdio_ctl;
struct memac_mdio_controller *regs = bus->priv;
u32 c45 = 1;
+ int err;
if (dev_addr == MDIO_DEVAD_NONE) {
if (!strcmp(bus->name, DEFAULT_FM_TGEC_MDIO_NAME))
@@ -97,9 +137,9 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
} else
memac_setbits_32(®s->mdio_stat, MDIO_STAT_ENC);
- /* Wait till the bus is free */
- while ((memac_in_32(®s->mdio_stat)) & MDIO_STAT_BSY)
- ;
+ err = memac_wait_until_free(regs);
+ if (err)
+ return err;
/* Set the Port and Device Addrs */
mdio_ctl = MDIO_CTL_PORT_ADDR(port_addr) | MDIO_CTL_DEV_ADDR(dev_addr);
@@ -109,17 +149,17 @@ int memac_mdio_read(struct mii_dev *bus, int port_addr, int dev_addr,
if (c45)
memac_out_32(®s->mdio_addr, regnum & 0xffff);
- /* Wait till the bus is free */
- while ((memac_in_32(®s->mdio_stat)) & MDIO_STAT_BSY)
- ;
+ err = memac_wait_until_free(regs);
+ if (err)
+ return err;
/* Initiate the read */
mdio_ctl |= MDIO_CTL_READ;
memac_out_32(®s->mdio_ctl, mdio_ctl);
- /* Wait till the MDIO write is complete */
- while ((memac_in_32(®s->mdio_data)) & MDIO_DATA_BSY)
- ;
+ err = memac_wait_until_done(regs);
+ if (err)
+ return err;
/* Return all Fs if nothing was there */
if (memac_in_32(®s->mdio_stat) & MDIO_STAT_RD_ER)
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH] net: memac_phy: add a timeout to MDIO operations
2020-12-09 11:31 [PATCH] net: memac_phy: add a timeout to MDIO operations Ioana Ciornei
@ 2020-12-09 13:04 ` Madalin Bucur
0 siblings, 0 replies; 2+ messages in thread
From: Madalin Bucur @ 2020-12-09 13:04 UTC (permalink / raw)
To: u-boot
> -----Original Message-----
> From: Ioana Ciornei <ioana.ciornei@nxp.com>
> Sent: 09 December 2020 13:32
> To: joe.hershberger at ni.com; Tom Rini <trini@konsulko.com>; u-
> boot at lists.denx.de
> Cc: Madalin Bucur <madalin.bucur@nxp.com>; Florin Laurentiu Chiculita
> <florinlaurentiu.chiculita@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>
> Subject: [PATCH] net: memac_phy: add a timeout to MDIO operations
>
> We have encountered circumstances when a board design does not include
> pull-up resistors on the external MDIO buses which are not used. This
> leads to the MDIO data line not being pulled-up, thus the MDIO controller
> will always see the line as busy.
>
> Without a timeout in the MDIO bus driver, the execution is stuck in an
> infinite loop when any access is initiated on that external bus.
>
> Add a timeout in the driver so that we are protected in this
> circumstance. This is similar to what is being done in the Linux
> xgmac_mdio driver.
>
> Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> ---
> drivers/net/fm/memac_phy.c | 76 +++++++++++++++++++++++++++++---------
> 1 file changed, 58 insertions(+), 18 deletions(-)
Reviewed-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-12-09 11:31 [PATCH] net: memac_phy: add a timeout to MDIO operations Ioana Ciornei
2020-12-09 13:04 ` Madalin Bucur
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