Messages in this thread | | | Date | Wed, 5 May 2021 03:04:47 +0200 | From | Andrew Lunn <> | Subject | Re: [RFC PATCH net-next v3 15/20] net: dsa: qca8k: dsa: qca8k: protect MASTER busy_wait with mdio mutex |
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On Wed, May 05, 2021 at 12:29:09AM +0200, Ansuel Smith wrote: > MDIO_MASTER operation have a dedicated busy wait that is not protected > by the mdio mutex. This can cause situation where the MASTER operation > is done and a normal operation is executed between the MASTER read/write > and the MASTER busy_wait. Rework the qca8k_mdio_read/write function to > address this issue by binding the lock for the whole MASTER operation > and not only the mdio read/write common operation. > > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> > --- > drivers/net/dsa/qca8k.c | 69 ++++++++++++++++++++++++++++++++++------- > 1 file changed, 57 insertions(+), 12 deletions(-) > > diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c > index b21835d719b5..27234dd4c74a 100644 > --- a/drivers/net/dsa/qca8k.c > +++ b/drivers/net/dsa/qca8k.c > @@ -633,9 +633,33 @@ qca8k_port_to_phy(int port) > return port - 1; > } > > +static int > +qca8k_mdio_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask) > +{ > + unsigned long timeout; > + u16 r1, r2, page; > + > + qca8k_split_addr(reg, &r1, &r2, &page); > + > + timeout = jiffies + msecs_to_jiffies(20); > + > + /* loop until the busy flag has cleared */ > + do { > + u32 val = qca8k_mii_read32(priv->bus, 0x10 | r2, r1); > + int busy = val & mask; > + > + if (!busy) > + break; > + cond_resched(); > + } while (!time_after_eq(jiffies, timeout));
include/linux/iopoll.h
> + > + return time_after_eq(jiffies, timeout); > +} > + > static int > qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data) > { > + u16 r1, r2, page; > u32 phy, val; > int ret; > > @@ -651,12 +675,22 @@ qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data) > QCA8K_MDIO_MASTER_REG_ADDR(regnum) | > QCA8K_MDIO_MASTER_DATA(data); > > - ret = qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val); > + qca8k_split_addr(QCA8K_MDIO_MASTER_CTRL, &r1, &r2, &page); > + > + mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED); > + > + ret = qca8k_set_page(priv->bus, page); > if (ret) > - return ret; > + goto exit; > > - ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL, > - QCA8K_MDIO_MASTER_BUSY); > + qca8k_mii_write32(priv->bus, 0x10 | r2, r1, val); > + > + if (qca8k_mdio_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL, > + QCA8K_MDIO_MASTER_BUSY)) > + ret = -ETIMEDOUT;
qca8k_mdio_busy_wait() should be returning -EIMEDOUT.
Andrew
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