[PATCH] net:phy: Fix "Link is Down" issue

[PATCH] net:phy: Fix "Link is Down" issue

[Dylan Hung]

The issue happened randomly in runtime.  The message "Link is Down" is
popped but soon it recovered to "Link is Up".

The "Link is Down" results from the incorrect read data for reading the
PHY register via MDIO bus.  The correct sequence for reading the data
shall be:
1. fire the command
2. wait for command done (this step was missing)
3. wait for data idle
4. read data from data register

Fixes: a9770eac511a ("net: mdio: Move MDIO drivers into a new subdirectory")
Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
---
 drivers/net/mdio/mdio-aspeed.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
index cad820568f75..966c3b4ad59d 100644
--- a/drivers/net/mdio/mdio-aspeed.c
+++ b/drivers/net/mdio/mdio-aspeed.c
@@ -61,6 +61,13 @@ static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
 
 	iowrite32(ctrl, ctx->base + ASPEED_MDIO_CTRL);
 
+	rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_CTRL, ctrl,
+				!(ctrl & ASPEED_MDIO_CTRL_FIRE),
+				ASPEED_MDIO_INTERVAL_US,
+				ASPEED_MDIO_TIMEOUT_US);
+	if (rc < 0)
+		return rc;
+
 	rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_DATA, data,
 				data & ASPEED_MDIO_DATA_IDLE,
 				ASPEED_MDIO_INTERVAL_US,
-- 
2.25.1

[PATCH] net:phy: Fix "Link is Down" issue

[Joel Stanley]

On Wed, 24 Nov 2021 at 06:11, Dylan Hung <dylan_hung@aspeedtech.com> wrote:
>
> The issue happened randomly in runtime.  The message "Link is Down" is
> popped but soon it recovered to "Link is Up".
>
> The "Link is Down" results from the incorrect read data for reading the
> PHY register via MDIO bus.  The correct sequence for reading the data
> shall be:
> 1. fire the command
> 2. wait for command done (this step was missing)
> 3. wait for data idle
> 4. read data from data register

I consulted the datasheet and it doesn't mention this. Perhaps
something to be added?

Reviewed-by: Joel Stanley <joel@jms.id.au>

>
> Fixes: a9770eac511a ("net: mdio: Move MDIO drivers into a new subdirectory")

I think this should be:

Fixes: f160e99462c6 ("net: phy: Add mdio-aspeed")

We should cc stable too.

> Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
> ---
>  drivers/net/mdio/mdio-aspeed.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
> index cad820568f75..966c3b4ad59d 100644
> --- a/drivers/net/mdio/mdio-aspeed.c
> +++ b/drivers/net/mdio/mdio-aspeed.c
> @@ -61,6 +61,13 @@ static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
>
>         iowrite32(ctrl, ctx->base + ASPEED_MDIO_CTRL);
>
> +       rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_CTRL, ctrl,
> +                               !(ctrl & ASPEED_MDIO_CTRL_FIRE),
> +                               ASPEED_MDIO_INTERVAL_US,
> +                               ASPEED_MDIO_TIMEOUT_US);
> +       if (rc < 0)
> +               return rc;
> +
>         rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_DATA, data,
>                                 data & ASPEED_MDIO_DATA_IDLE,
>                                 ASPEED_MDIO_INTERVAL_US,
> --
> 2.25.1
>

[PATCH] net:phy: Fix "Link is Down" issue

[Dylan Hung]

> -----Original Message-----
> From: Joel Stanley [mailto:joel at jms.id.au]
> Sent: 2021?11?24? 6:06 PM
> To: Dylan Hung <dylan_hung@aspeedtech.com>
> Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>; linux-aspeed
> <linux-aspeed@lists.ozlabs.org>; Linux ARM
> <linux-arm-kernel@lists.infradead.org>; Networking
> <netdev@vger.kernel.org>; Andrew Jeffery <andrew@aj.id.au>; Jakub Kicinski
> <kuba@kernel.org>; David S . Miller <davem@davemloft.net>; Russell King
> <linux@armlinux.org.uk>; hkallweit1 at gmail.com; Andrew Lunn
> <andrew@lunn.ch>; BMC-SW <BMC-SW@aspeedtech.com>
> Subject: Re: [PATCH] net:phy: Fix "Link is Down" issue
> 
> On Wed, 24 Nov 2021 at 06:11, Dylan Hung <dylan_hung@aspeedtech.com>
> wrote:
> >
> > The issue happened randomly in runtime.  The message "Link is Down" is
> > popped but soon it recovered to "Link is Up".
> >
> > The "Link is Down" results from the incorrect read data for reading
> > the PHY register via MDIO bus.  The correct sequence for reading the
> > data shall be:
> > 1. fire the command
> > 2. wait for command done (this step was missing) 3. wait for data idle
> > 4. read data from data register
> 
> I consulted the datasheet and it doesn't mention this. Perhaps something to be
> added?
We will add this sequence into the datasheet, thank you.
> 
> Reviewed-by: Joel Stanley <joel@jms.id.au>
> 
> >
> > Fixes: a9770eac511a ("net: mdio: Move MDIO drivers into a new
> > subdirectory")
> 
> I think this should be:
> 
> Fixes: f160e99462c6 ("net: phy: Add mdio-aspeed")
I will change this in V2.
> 
> We should cc stable too.
I will change this in V2.
> 
> > Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
> > ---
> >  drivers/net/mdio/mdio-aspeed.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/net/mdio/mdio-aspeed.c
> > b/drivers/net/mdio/mdio-aspeed.c index cad820568f75..966c3b4ad59d
> > 100644
> > --- a/drivers/net/mdio/mdio-aspeed.c
> > +++ b/drivers/net/mdio/mdio-aspeed.c
> > @@ -61,6 +61,13 @@ static int aspeed_mdio_read(struct mii_bus *bus,
> > int addr, int regnum)
> >
> >         iowrite32(ctrl, ctx->base + ASPEED_MDIO_CTRL);
> >
> > +       rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_CTRL, ctrl,
> > +                               !(ctrl & ASPEED_MDIO_CTRL_FIRE),
> > +                               ASPEED_MDIO_INTERVAL_US,
> > +                               ASPEED_MDIO_TIMEOUT_US);
> > +       if (rc < 0)
> > +               return rc;
> > +
> >         rc = readl_poll_timeout(ctx->base + ASPEED_MDIO_DATA, data,
> >                                 data & ASPEED_MDIO_DATA_IDLE,
> >                                 ASPEED_MDIO_INTERVAL_US,
> > --
> > 2.25.1
> >

[PATCH] net:phy: Fix "Link is Down" issue

[Andrew Lunn]

> We should cc stable too.

https://www.kernel.org/doc/html/v5.12/networking/netdev-FAQ.html#how-do-i-indicate-which-tree-net-vs-net-next-my-patch-should-be-in

	Andrew

[PATCH] net:phy: Fix "Link is Down" issue

[Jakub Kicinski]

On Wed, 24 Nov 2021 14:10:57 +0800 Dylan Hung wrote:
> Subject: [PATCH] net:phy: Fix "Link is Down" issue

Since there will be v2, please also add a space between net: and phy:.

[PATCH] net:phy: Fix "Link is Down" issue

[Dylan Hung]

> -----Original Message-----
> From: Jakub Kicinski [mailto:kuba at kernel.org]
> Sent: 2021?11?25? 7:31 AM
> To: Dylan Hung <dylan_hung@aspeedtech.com>
> Cc: linux-kernel at vger.kernel.org; linux-aspeed at lists.ozlabs.org;
> linux-arm-kernel at lists.infradead.org; netdev at vger.kernel.org;
> andrew at aj.id.au; joel at jms.id.au; davem at davemloft.net;
> linux at armlinux.org.uk; hkallweit1 at gmail.com; andrew at lunn.ch; BMC-SW
> <BMC-SW@aspeedtech.com>
> Subject: Re: [PATCH] net:phy: Fix "Link is Down" issue
> 
> On Wed, 24 Nov 2021 14:10:57 +0800 Dylan Hung wrote:
> > Subject: [PATCH] net:phy: Fix "Link is Down" issue
> 
> Since there will be v2, please also add a space between net: and phy:.

Should I use "net: mdio: " instead of "net: phy: "? Since this file was moved from net/phy to net/mdio by commit a9770eac511a.

[PATCH] net:phy: Fix "Link is Down" issue

[Jakub Kicinski]

On Thu, 25 Nov 2021 01:42:08 +0000 Dylan Hung wrote:
> > -----Original Message-----
> > From: Jakub Kicinski [mailto:kuba at kernel.org]
> > Sent: 2021?11?25? 7:31 AM
> > To: Dylan Hung <dylan_hung@aspeedtech.com>
> > Cc: linux-kernel at vger.kernel.org; linux-aspeed at lists.ozlabs.org;
> > linux-arm-kernel at lists.infradead.org; netdev at vger.kernel.org;
> > andrew at aj.id.au; joel at jms.id.au; davem at davemloft.net;
> > linux at armlinux.org.uk; hkallweit1 at gmail.com; andrew at lunn.ch; BMC-SW
> > <BMC-SW@aspeedtech.com>
> > Subject: Re: [PATCH] net:phy: Fix "Link is Down" issue
> > 
> > On Wed, 24 Nov 2021 14:10:57 +0800 Dylan Hung wrote:  
> > > Subject: [PATCH] net:phy: Fix "Link is Down" issue  
> > 
> > Since there will be v2, please also add a space between net: and phy:.  
> 
> Should I use "net: mdio: " instead of "net: phy: "? Since this file was moved from net/phy to net/mdio by commit a9770eac511a.

Since you asked, I'd go for mdio: aspeed:, without the net part.

[PATCH] net:phy: Fix "Link is Down" issue

[Dylan Hung]

> -----Original Message-----
> From: Andrew Lunn [mailto:andrew at lunn.ch]
> Sent: 2021?11?24? 11:30 PM
> To: Joel Stanley <joel@jms.id.au>
> Cc: Dylan Hung <dylan_hung@aspeedtech.com>; Linux Kernel Mailing List
> <linux-kernel@vger.kernel.org>; linux-aspeed <linux-aspeed@lists.ozlabs.org>;
> Linux ARM <linux-arm-kernel@lists.infradead.org>; Networking
> <netdev@vger.kernel.org>; Andrew Jeffery <andrew@aj.id.au>; Jakub Kicinski
> <kuba@kernel.org>; David S . Miller <davem@davemloft.net>; Russell King
> <linux@armlinux.org.uk>; hkallweit1 at gmail.com; BMC-SW
> <BMC-SW@aspeedtech.com>
> Subject: Re: [PATCH] net:phy: Fix "Link is Down" issue
> 
> > We should cc stable too.
> 
> https://www.kernel.org/doc/html/v5.12/networking/netdev-FAQ.html#how-do-
> i-indicate-which-tree-net-vs-net-next-my-patch-should-be-in
> 
> 	Andrew

Sorry, I got this mail after I sent v2 out.  Should I prepare patch v3 with --subject-prefix='PATCH net'?

[PATCH] net:phy: Fix "Link is Down" issue

[Jakub Kicinski]

On Thu, 25 Nov 2021 03:08:22 +0000 Dylan Hung wrote:
> > > We should cc stable too.  
> > 
> > https://www.kernel.org/doc/html/v5.12/networking/netdev-FAQ.html#how-do-
> > i-indicate-which-tree-net-vs-net-next-my-patch-should-be-in
>
> Sorry, I got this mail after I sent v2 out.  Should I prepare patch
> v3 with --subject-prefix='PATCH net'?

That's leave it be now, but please keep this in mind in the future.