| Message ID | 20180509154515.5968-1-nsekhar@ti.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,next-next] drivers: net: davinci_mdio: prevent spurious timeout | expand |
On 05/09/2018 10:45 AM, Sekhar Nori wrote: > A well timed kernel preemption in the time_after() loop > in wait_for_idle() can result in a spurious timeout > error to be returned. > > Fix it by using readl_poll_timeout() which takes care of > this issue. > > Reviewed-by: Andrew Lunn <andrew@lunn.ch> > Signed-off-by: Sekhar Nori <nsekhar@ti.com> > --- > v3: simplify return path based on comment from Andrew > > The issue has not been personally observed by me, but has > been reported by users. Sending for next-next given the > non-critical nature. There is seems to be no easy way to > reproduce this. > Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com> -- regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Sekhar Nori <nsekhar@ti.com> Date: Wed, 9 May 2018 21:15:15 +0530 > A well timed kernel preemption in the time_after() loop > in wait_for_idle() can result in a spurious timeout > error to be returned. > > Fix it by using readl_poll_timeout() which takes care of > this issue. > > Reviewed-by: Andrew Lunn <andrew@lunn.ch> > Signed-off-by: Sekhar Nori <nsekhar@ti.com> Applied. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/ethernet/ti/davinci_mdio.c b/drivers/net/ethernet/ti/davinci_mdio.c index 3c33f4504d8e..98a1c97fb95e 100644 --- a/drivers/net/ethernet/ti/davinci_mdio.c +++ b/drivers/net/ethernet/ti/davinci_mdio.c @@ -34,6 +34,7 @@ #include <linux/clk.h> #include <linux/err.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/pm_runtime.h> #include <linux/davinci_emac.h> #include <linux/of.h> @@ -227,14 +228,14 @@ static inline int wait_for_user_access(struct davinci_mdio_data *data) static inline int wait_for_idle(struct davinci_mdio_data *data) { struct davinci_mdio_regs __iomem *regs = data->regs; - unsigned long timeout = jiffies + msecs_to_jiffies(MDIO_TIMEOUT); + u32 val, ret; - while (time_after(timeout, jiffies)) { - if (__raw_readl(®s->control) & CONTROL_IDLE) - return 0; - } - dev_err(data->dev, "timed out waiting for idle\n"); - return -ETIMEDOUT; + ret = readl_poll_timeout(®s->control, val, val & CONTROL_IDLE, + 0, MDIO_TIMEOUT * 1000); + if (ret) + dev_err(data->dev, "timed out waiting for idle\n"); + + return ret; } static int davinci_mdio_read(struct mii_bus *bus, int phy_id, int phy_reg)