linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Vladimir Oltean <olteanv@gmail.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Prasanna Vengateshan <prasanna.vengateshan@microchip.com>,
	Andrew Lunn <andrew@lunn.ch>,
	netdev@vger.kernel.org, robh+dt@kernel.org,
	UNGLinuxDriver@microchip.com, Woojung.Huh@microchip.com,
	hkallweit1@gmail.com, davem@davemloft.net, kuba@kernel.org,
	linux-kernel@vger.kernel.org, vivien.didelot@gmail.com,
	f.fainelli@gmail.com, devicetree@vger.kernel.org
Subject: Re: [PATCH v3 net-next 05/10] net: dsa: microchip: add DSA support for microchip lan937x
Date: Wed, 4 Aug 2021 13:46:25 +0300	[thread overview]
Message-ID: <20210804104625.d2qw3gr7algzppz5@skbuf> (raw)
In-Reply-To: <20210804095954.GN22278@shell.armlinux.org.uk>

On Wed, Aug 04, 2021 at 10:59:54AM +0100, Russell King (Oracle) wrote:
> This is why we need to have a clear definition of what the various
> RGMII interface types are, how and where they are applied, and make
> sure everyone sticks to that. We have this documented in
> Documentation/networking/phy.rst.

The problem is that I have no clear migration path for the drivers I
maintain, like sja1105, and I suspect that others might be in the exact
same situation.

Currently, if the sja1105 needs to add internal delays in a MAC-to-MAC
(fixed-link) setup, it does that based on the phy-mode string. So
"rgmii-id" + "fixed-link" means for sja1105 "add RX and TX RGMII
internal delays", even though the documentation now says "the MAC should
not add the RX or TX delays in this case".

There are 2 cases to think about, old driver with new DT blob and new
driver with old DT blob. If breakage is involved, I am not actually very
interested in doing the migration, because even though the interpretation
of the phy-mode string is inconsistent between the phy-handle and fixed-link
case (which was deliberate), at least it currently does all that I need it to.

I am not even clear what is the expected canonical behavior for a MAC
driver. It parses rx-internal-delay-ps and tx-internal-delay-ps, and
then what? It treats all "rgmii*" phy-mode strings identically? Or is it
an error to have "rgmii-rxid" for phy-mode and non-zero rx-internal-delay-ps?
If it is an error, should all MAC drivers check for it? And if it is an
error, does it not make migration even more difficult (adding an
rx-internal-delay-ps property to a MAC OF node which already uses
"rgmii-id" would be preferable to also having to change the "rgmii-id"
to "rgmii", because an old kernel might also need to work with that DT
blob, and that will ignore the new rx-internal-delay-ps property).

Does qca8k_setup_of_rgmii_delay(), a very recent function, even do the
right thing with rx-internal-delay-ps, or is it doing the exact opposite
of the right thing (it applies rx-internal-delay-ps when in rgmii-id or
rgmii-rxid mode).

  reply	other threads:[~2021-08-04 10:46 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 17:30 [PATCH v3 net-next 00/10] net: dsa: microchip: DSA driver support for LAN937x switch Prasanna Vengateshan
2021-07-23 17:30 ` [PATCH v3 net-next 01/10] dt-bindings: net: dsa: dt bindings for microchip lan937x Prasanna Vengateshan
2021-07-26 22:49   ` Rob Herring
2021-07-23 17:31 ` [PATCH v3 net-next 02/10] net: dsa: move mib->cnt_ptr reset code to ksz_common.c Prasanna Vengateshan
2021-07-23 18:53   ` Vladimir Oltean
2021-07-23 17:31 ` [PATCH v3 net-next 03/10] net: phy: Add support for LAN937x T1 phy driver Prasanna Vengateshan
2021-08-11 17:52   ` Prasanna Vengateshan
2021-07-23 17:31 ` [PATCH v3 net-next 04/10] net: dsa: tag_ksz: add tag handling for Microchip LAN937x Prasanna Vengateshan
2021-07-23 19:23   ` Vladimir Oltean
2021-07-23 17:31 ` [PATCH v3 net-next 05/10] net: dsa: microchip: add DSA support for microchip lan937x Prasanna Vengateshan
2021-07-31 15:04   ` Vladimir Oltean
2021-07-31 22:05     ` Andrew Lunn
2021-08-02 21:33       ` Vladimir Oltean
2021-08-03 14:43         ` Andrew Lunn
2021-08-03 15:05           ` Vladimir Oltean
2021-08-02 10:45     ` Prasanna Vengateshan
2021-08-02 12:15       ` Vladimir Oltean
2021-08-02 13:13         ` Andrew Lunn
2021-08-02 13:59           ` Vladimir Oltean
2021-08-02 20:47             ` Andrew Lunn
2021-08-03 16:54             ` Prasanna Vengateshan
2021-08-03 23:54               ` Vladimir Oltean
2021-08-04  9:59                 ` Russell King (Oracle)
2021-08-04 10:46                   ` Vladimir Oltean [this message]
2021-08-04 14:28                     ` Prasanna Vengateshan
2021-08-04 14:51                       ` Vladimir Oltean
2021-08-07 15:40                     ` Andrew Lunn
2021-08-07 17:00                       ` Vladimir Oltean
2021-08-11 17:44                       ` Prasanna Vengateshan
2021-08-11 18:23                         ` Andrew Lunn
2021-08-11 20:14                           ` Russell King (Oracle)
2021-08-11 20:20                             ` Vladimir Oltean
2021-08-11 20:22                               ` Andrew Lunn
2021-07-23 17:31 ` [PATCH v3 net-next 06/10] net: dsa: microchip: add support for phylink management Prasanna Vengateshan
2021-07-31 15:27   ` Vladimir Oltean
2021-08-03 17:04     ` Prasanna Vengateshan
2021-07-23 17:31 ` [PATCH v3 net-next 07/10] net: dsa: microchip: add support for ethtool port counters Prasanna Vengateshan
2021-07-23 17:31 ` [PATCH v3 net-next 08/10] net: dsa: microchip: add support for port mirror operations Prasanna Vengateshan
2021-07-31 15:24   ` Vladimir Oltean
2021-07-23 17:31 ` [PATCH v3 net-next 09/10] net: dsa: microchip: add support for fdb and mdb management Prasanna Vengateshan
2021-07-31 15:19   ` Vladimir Oltean
2021-07-23 17:31 ` [PATCH v3 net-next 10/10] net: dsa: microchip: add support for vlan operations Prasanna Vengateshan
2021-07-31 15:08   ` Vladimir Oltean
2021-08-02 10:48     ` Prasanna Vengateshan

Reply instructions:

You may reply publicly 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=20210804104625.d2qw3gr7algzppz5@skbuf \
    --to=olteanv@gmail.com \
    --cc=UNGLinuxDriver@microchip.com \
    --cc=Woojung.Huh@microchip.com \
    --cc=andrew@lunn.ch \
    --cc=davem@davemloft.net \
    --cc=devicetree@vger.kernel.org \
    --cc=f.fainelli@gmail.com \
    --cc=hkallweit1@gmail.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=netdev@vger.kernel.org \
    --cc=prasanna.vengateshan@microchip.com \
    --cc=robh+dt@kernel.org \
    --cc=vivien.didelot@gmail.com \
    --subject='Re: [PATCH v3 net-next 05/10] net: dsa: microchip: add DSA support for microchip lan937x' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).