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Date: Thu, 3 May 2018 13:08:43 +0300 From: Claudiu Beznea <Claudiu.Beznea@...rochip.com> To: <harinikatakamlinux@...il.com>, <nicolas.ferre@...el.com>, <davem@...emloft.net> CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <harinik@...inx.com>, <michals@...inx.com>, <appanad@...inx.com>, Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com> Subject: Re: [RFC PATCH 1/5] net: macb: Check MDIO state before read/write and use timeouts On 22.03.2018 15:51, harinikatakamlinux@...il.com wrote: > From: Harini Katakam <harinik@...inx.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@...inx.com> > Signed-off-by: Harini Katakam <harinik@...inx.com> > --- > drivers/net/ethernet/cadence/macb_main.c | 54 ++++++++++++++++++++++++++++++-- > 1 file changed, 52 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c > index d09bd43..f4030c1 100644 > --- a/drivers/net/ethernet/cadence/macb_main.c > +++ b/drivers/net/ethernet/cadence/macb_main.c > @@ -321,6 +321,21 @@ static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum) > { > struct macb *bp = bus->priv; > int value; > + ulong timeout; > + > + timeout = jiffies + msecs_to_jiffies(1000); > + /* wait for end of transfer */ > + do { > + if (MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + break; > + > + cpu_relax(); > + } while (!time_after_eq(jiffies, timeout)); > + > + if (time_after_eq(jiffies, timeout)) { > + netdev_err(bp->dev, "wait for end of transfer timed out\n"); > + return -ETIMEDOUT; > + } Wouldn't be cleaner to keep it in this way: while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR))) { if (time_after_eq(jiffies, timeout) { netdev_err(bp->dev, "wait for end of transfer timed out\n"); return -ETIMEDOUT; } cpu_relax(); } > > macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_SOF) > | MACB_BF(RW, MACB_MAN_READ) > @@ -328,9 +343,19 @@ static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum) > | MACB_BF(REGA, regnum) > | MACB_BF(CODE, MACB_MAN_CODE))); > > + timeout = jiffies + msecs_to_jiffies(1000); > /* wait for end of transfer */ > - while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + do { > + if (MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + break; > + > cpu_relax(); > + } while (!time_after_eq(jiffies, timeout)); > + > + if (time_after_eq(jiffies, timeout)) { > + netdev_err(bp->dev, "wait for end of transfer timed out\n"); > + return -ETIMEDOUT; > + } > > value = MACB_BFEXT(DATA, macb_readl(bp, MAN)); > > @@ -341,6 +366,21 @@ static int macb_mdio_write(struct mii_bus *bus, int mii_id, int regnum, > u16 value) > { > struct macb *bp = bus->priv; > + ulong timeout; > + > + timeout = jiffies + msecs_to_jiffies(1000); > + /* wait for end of transfer */ > + do { > + if (MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + break; > + > + cpu_relax(); > + } while (!time_after_eq(jiffies, timeout)); > + > + if (time_after_eq(jiffies, timeout)) { > + netdev_err(bp->dev, "wait for end of transfer timed out\n"); > + return -ETIMEDOUT; > + } > > macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_SOF) > | MACB_BF(RW, MACB_MAN_WRITE) > @@ -349,9 +389,19 @@ static int macb_mdio_write(struct mii_bus *bus, int mii_id, int regnum, > | MACB_BF(CODE, MACB_MAN_CODE) > | MACB_BF(DATA, value))); > > + timeout = jiffies + msecs_to_jiffies(1000); > /* wait for end of transfer */ > - while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + do { > + if (MACB_BFEXT(IDLE, macb_readl(bp, NSR))) > + break; > + > cpu_relax(); > + } while (!time_after_eq(jiffies, timeout)); > + > + if (time_after_eq(jiffies, timeout)) { > + netdev_err(bp->dev, "wait for end of transfer timed out\n"); > + return -ETIMEDOUT; > + } > > return 0; > } >
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