[PATCH] net/fsl: remove func xgmac_wait_until_free() as duplicate

[PATCH] net/fsl: remove func xgmac_wait_until_free() as duplicate

[Alexandru Ardelean]

Looking at xgmac_wait_until_done() and xgmac_wait_until_free()
functions, they seem to have turned out completely identical.

Though, judging from the git history it seems they
initially weren't.

Remove xgmac_wait_until_free() in favor of xgmac_wait_until_done().

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
---
 drivers/net/ethernet/freescale/xgmac_mdio.c | 33 ++++-------------------------
 1 file changed, 4 insertions(+), 29 deletions(-)

diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
index e03b30c..54597a8 100644
--- a/drivers/net/ethernet/freescale/xgmac_mdio.c
+++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
@@ -71,31 +71,6 @@ static void xgmac_write32(u32 value,
 }
 
 /*
- * Wait until the MDIO bus is free
- */
-static int xgmac_wait_until_free(struct device *dev,
-				 struct tgec_mdio_controller __iomem *regs,
-				 bool is_little_endian)
-{
-	unsigned int timeout;
-
-	/* Wait till the bus is free */
-	timeout = TIMEOUT;
-	while ((xgmac_read32(&regs->mdio_stat, is_little_endian) &
-		MDIO_STAT_BSY) && timeout) {
-		cpu_relax();
-		timeout--;
-	}
-
-	if (!timeout) {
-		dev_err(dev, "timeout waiting for bus to be free\n");
-		return -ETIMEDOUT;
-	}
-
-	return 0;
-}
-
-/*
  * Wait till the MDIO read or write operation is complete
  */
 static int xgmac_wait_until_done(struct device *dev,
@@ -147,7 +122,7 @@ static int xgmac_mdio_write(struct mii_bus *bus, int phy_id, int regnum, u16 val
 
 	xgmac_write32(mdio_stat, &regs->mdio_stat, endian);
 
-	ret = xgmac_wait_until_free(&bus->dev, regs, endian);
+	ret = xgmac_wait_until_done(&bus->dev, regs, endian);
 	if (ret)
 		return ret;
 
@@ -159,7 +134,7 @@ static int xgmac_mdio_write(struct mii_bus *bus, int phy_id, int regnum, u16 val
 	if (regnum & MII_ADDR_C45) {
 		xgmac_write32(regnum & 0xffff, &regs->mdio_addr, endian);
 
-		ret = xgmac_wait_until_free(&bus->dev, regs, endian);
+		ret = xgmac_wait_until_done(&bus->dev, regs, endian);
 		if (ret)
 			return ret;
 	}
@@ -201,7 +176,7 @@ static int xgmac_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
 
 	xgmac_write32(mdio_stat, &regs->mdio_stat, endian);
 
-	ret = xgmac_wait_until_free(&bus->dev, regs, endian);
+	ret = xgmac_wait_until_done(&bus->dev, regs, endian);
 	if (ret)
 		return ret;
 
@@ -213,7 +188,7 @@ static int xgmac_mdio_read(struct mii_bus *bus, int phy_id, int regnum)
 	if (regnum & MII_ADDR_C45) {
 		xgmac_write32(regnum & 0xffff, &regs->mdio_addr, endian);
 
-		ret = xgmac_wait_until_free(&bus->dev, regs, endian);
+		ret = xgmac_wait_until_done(&bus->dev, regs, endian);
 		if (ret)
 			return ret;
 	}
-- 
2.7.4

Re: [PATCH] net/fsl: remove func xgmac_wait_until_free() as duplicate

[David Miller]

From: Alexandru Ardelean <ardeleanalex@gmail.com>
Date: Mon,  8 May 2017 14:31:18 +0300

> Looking at xgmac_wait_until_done() and xgmac_wait_until_free()
> functions, they seem to have turned out completely identical.
> 
> Though, judging from the git history it seems they
> initially weren't.
> 
> Remove xgmac_wait_until_free() in favor of xgmac_wait_until_done().
> 
> Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

This situation got created by the commit below, I wonder if it
is even correct.

Certainly the original author of this code intended the MDIO
_data_ rather than the _status_ register to be polled.

Otherwise, why in the world have two functions which are in
every other regard identical?

commit 26eee0210ad72a29eb4a70b34320bda266f91a0d
Author: Shaohui Xie <Shaohui.Xie@freescale.com>
Date:   Mon Mar 16 18:55:50 2015 +0800

    net/fsl: fix a bug in xgmac_mdio
    
    There is a bug in xgmac_wait_until_done() which mdio_stat should be used
    instead of mdio_data when checking if busy bit is cleared.
    
    Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
index 3a83bc2..5f691f2 100644
--- a/drivers/net/ethernet/freescale/xgmac_mdio.c
+++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
@@ -79,7 +79,7 @@ static int xgmac_wait_until_done(struct device *dev,
 
 	/* Wait till the MDIO write is complete */
 	timeout = TIMEOUT;
-	while ((ioread32be(&regs->mdio_data) & MDIO_DATA_BSY) && timeout) {
+	while ((ioread32be(&regs->mdio_stat) & MDIO_STAT_BSY) && timeout) {
 		cpu_relax();
 		timeout--;
 	}

Re: [PATCH] net/fsl: remove func xgmac_wait_until_free() as duplicate

[Alexandru Ardelean]

On Mon, May 8, 2017 at 10:34 PM, David Miller <davem@davemloft.net> wrote:
> From: Alexandru Ardelean <ardeleanalex@gmail.com>
> Date: Mon,  8 May 2017 14:31:18 +0300
>
>> Looking at xgmac_wait_until_done() and xgmac_wait_until_free()
>> functions, they seem to have turned out completely identical.
>>
>> Though, judging from the git history it seems they
>> initially weren't.
>>
>> Remove xgmac_wait_until_free() in favor of xgmac_wait_until_done().
>>
>> Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
>
> This situation got created by the commit below, I wonder if it
> is even correct.
>
> Certainly the original author of this code intended the MDIO
> _data_ rather than the _status_ register to be polled.
>
> Otherwise, why in the world have two functions which are in
> every other regard identical?

[ Removed Shaohui.Xie@nxp.com email from thread ; seems email addr no
longer valid ].

I should have added an RFC tag.
Thing is, we just use this driver, so, I can't offer much input here.

I was debugging [a while ago] some other issue related to this and
stumbled over this.
I haven't seem any obvious issues yet, to suggest one thing or or the
other [regarding polling status or data registers].

I would have liked some input from some NXP/Freescale people on this email list.
Or maybe I could forward this to more people that contribute the NXP eco-system.

If you have any suggestions, please advise and I'll adapt.

Thanks
Alex

>
> commit 26eee0210ad72a29eb4a70b34320bda266f91a0d
> Author: Shaohui Xie <Shaohui.Xie@freescale.com>
> Date:   Mon Mar 16 18:55:50 2015 +0800
>
>     net/fsl: fix a bug in xgmac_mdio
>
>     There is a bug in xgmac_wait_until_done() which mdio_stat should be used
>     instead of mdio_data when checking if busy bit is cleared.
>
>     Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
>     Signed-off-by: David S. Miller <davem@davemloft.net>
>
> diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
> index 3a83bc2..5f691f2 100644
> --- a/drivers/net/ethernet/freescale/xgmac_mdio.c
> +++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
> @@ -79,7 +79,7 @@ static int xgmac_wait_until_done(struct device *dev,
>
>         /* Wait till the MDIO write is complete */
>         timeout = TIMEOUT;
> -       while ((ioread32be(&regs->mdio_data) & MDIO_DATA_BSY) && timeout) {
> +       while ((ioread32be(&regs->mdio_stat) & MDIO_STAT_BSY) && timeout) {
>                 cpu_relax();
>                 timeout--;
>         }