Netdev Archive on lore.kernel.org
 help / color / Atom feed
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Andrew Lunn <andrew@lunn.ch>,
	netdev@vger.kernel.org,
	Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>,
	Michal Simek <michal.simek@xilinx.com>,
	linux-kernel@vger.kernel.org,
	Robert Hancock <hancock@sedsystems.ca>,
	"David S . Miller" <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 07/14] net: axienet: Fix SGMII support
Date: Fri, 10 Jan 2020 15:22:15 +0000
Message-ID: <20200110152215.GF25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200110150409.GD25745@shell.armlinux.org.uk>

On Fri, Jan 10, 2020 at 03:04:09PM +0000, Russell King - ARM Linux admin wrote:
> On Fri, Jan 10, 2020 at 02:20:38PM +0000, Andre Przywara wrote:
> > On Fri, 10 Jan 2020 15:04:15 +0100
> > Andrew Lunn <andrew@lunn.ch> wrote:
> > 
> > Hi Andrew,
> > 
> > > On Fri, Jan 10, 2020 at 11:54:08AM +0000, Andre Przywara wrote:
> > > > With SGMII, the MAC and the PHY can negotiate the link speed between
> > > > themselves, without the host needing to mediate between them.
> > > > Linux recognises this, and will call phylink's mac_config with the speed
> > > > member set to SPEED_UNKNOWN (-1).
> > > > Currently the axienet driver will bail out and complain about an
> > > > unsupported link speed.
> > > > 
> > > > Teach axienet's mac_config callback to leave the MAC's speed setting
> > > > alone if the requested speed is SPEED_UNKNOWN.  
> > > 
> > > Hi Andre
> > > 
> > > Is there an interrupt when SGMII signals a change in link state? If
> > > so, you should call phylink_mac_change().
> > 
> > Good point. The doc describes a "Auto-Negotiation Complete" interrupt
> > status bit, which signal that " ... auto-negotiation of the SGMII or
> > 1000BASE-X interface has completed."
> 
> It depends what they mean by "Auto-negotiation complete" in SGMII.
> SGMII can complete the handshake, yet the config_reg word indicate
> link down.  If such an update causes an "Auto-negotiation complete"
> interrupt, then that's sufficient.
> 
> However, looking at axienet_mac_pcs_get_state(), that is just reading
> back what the MAC was set to in axienet_mac_config(), which is not
> how this is supposed to work.  axienet_mac_pcs_get_state() is
> supposed to get the results of the SGMII/1000BASE-X "negotiation".
> That also needs to be fixed.

I found "pg138-axi-ethernet.pdf" online, which I guess is this IP.
It says for SGMII:

The results of the SGMII auto-negotiation can be read from the SGMII
Management Auto-Negotiation Link Partner Ability Base register
(Table 2-54). The speed of the subsystem should then be set to match.

and similar for 1000BASE-X (referencing the same register.)

However, what they give in table 2-54 is the 1000BASE-X version of
the config_reg word, not the SGMII version (which is different.)

Hmm, I guess there's probably some scope for phylink to start
handling an IEEE 802.3 compliant PCS accessed over MDIO rather
than having each network driver implement this, but for now your
axienet_mac_pcs_get_state() implementation needs to be reading
from the register described in table 2-54 and interpreting the
results according to whether state->interface is 802.3z or not.

Also note, don't set state->interface in axienet_mac_pcs_get_state(),
you will be passed the currently selected interface that was last
configured via axienet_mac_config().

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

  reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 11:54 [PATCH 00/14] net: axienet: Error handling, SGMII and 64-bit DMA fixes Andre Przywara
2020-01-10 11:54 ` [PATCH 01/14] net: xilinx: temac: Relax Kconfig dependencies Andre Przywara
2020-01-10 14:19   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 02/14] net: axienet: Propagate failure of DMA descriptor setup Andre Przywara
2020-01-10 14:54   ` Radhey Shyam Pandey
2020-01-10 17:53     ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path Andre Przywara
2020-01-10 15:14   ` Radhey Shyam Pandey
2020-01-10 15:43     ` Andre Przywara
2020-01-10 17:05       ` Radhey Shyam Pandey
2020-01-16 18:03         ` Andre Przywara
2020-01-20 18:32           ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 04/14] net: axienet: Improve DMA error handling Andre Przywara
2020-01-10 15:26   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 05/14] net: axienet: Factor out TX descriptor chain cleanup Andre Przywara
2020-01-10 18:04   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 06/14] net: axienet: Check for DMA mapping errors Andre Przywara
2020-01-13  5:54   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 07/14] net: axienet: Fix SGMII support Andre Przywara
2020-01-10 14:04   ` Andrew Lunn
2020-01-10 14:20     ` Andre Przywara
2020-01-10 14:26       ` Andrew Lunn
2020-01-10 15:04       ` Russell King - ARM Linux admin
2020-01-10 15:22         ` Russell King - ARM Linux admin [this message]
2020-01-10 17:04           ` Russell King - ARM Linux admin
2020-01-18 11:22             ` Russell King - ARM Linux admin
2020-01-20 14:50               ` Andre Przywara
2020-01-20 15:45                 ` Russell King - ARM Linux admin
2020-01-27 17:04                   ` Andre Przywara
2020-01-27 17:20                     ` Radhey Shyam Pandey
2020-01-27 18:53                     ` Russell King - ARM Linux admin
2020-01-10 14:58   ` Russell King - ARM Linux admin
2020-01-10 17:32     ` Andre Przywara
2020-01-10 18:05       ` Russell King - ARM Linux admin
2020-01-10 19:33         ` Andrew Lunn
2020-01-10 11:54 ` [PATCH 08/14] net: axienet: Drop MDIO interrupt registers from ethtools dump Andre Przywara
2020-01-13  6:02   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 09/14] net: axienet: Add mii-tool support Andre Przywara
2020-01-13  6:12   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 10/14] net: axienet: Wrap DMA pointer writes to prepare for 64 bit Andre Przywara
2020-01-10 11:54 ` [PATCH 11/14] net: axienet: Upgrade descriptors to hold 64-bit addresses Andre Przywara
2020-01-14 16:35   ` Radhey Shyam Pandey
2020-01-14 17:29     ` Andre Przywara
2020-01-10 11:54 ` [PATCH 12/14] net: axienet: Autodetect 64-bit DMA capability Andre Przywara
2020-01-10 14:08   ` Andrew Lunn
2020-01-10 14:13     ` Andre Przywara
2020-01-10 14:22       ` Andrew Lunn
2020-01-10 15:08         ` Andre Przywara
2020-01-10 15:22           ` Andrew Lunn
2020-01-14 17:03   ` Radhey Shyam Pandey
2020-01-14 17:41     ` Andre Przywara
2020-01-15  6:02       ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 13/14] net: axienet: Allow DMA to beyond 4GB Andre Przywara
2020-01-10 11:54 ` [PATCH 14/14] net: axienet: Update devicetree binding documentation Andre Przywara
2020-01-21 21:51   ` Rob Herring
2020-01-24 16:29     ` Andre Przywara
2020-01-27  9:28       ` Radhey Shyam Pandey

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200110152215.GF25745@shell.armlinux.org.uk \
    --to=linux@armlinux.org.uk \
    --cc=andre.przywara@arm.com \
    --cc=andrew@lunn.ch \
    --cc=davem@davemloft.net \
    --cc=hancock@sedsystems.ca \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michal.simek@xilinx.com \
    --cc=netdev@vger.kernel.org \
    --cc=radhey.shyam.pandey@xilinx.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Netdev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/netdev/0 netdev/git/0.git
	git clone --mirror https://lore.kernel.org/netdev/1 netdev/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 netdev netdev/ https://lore.kernel.org/netdev \
		netdev@vger.kernel.org
	public-inbox-index netdev

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.netdev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git