From: Calvin Johnson <calvin.johnson@oss.nxp.com>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>,
linux.cj@gmail.com, Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Cristi Sovaiala <cristian.sovaiala@nxp.com>,
Florin Laurentiu Chiculita <florinlaurentiu.chiculita@nxp.com>,
Ioana Ciornei <ioana.ciornei@nxp.com>,
Madalin Bucur <madalin.bucur@oss.nxp.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Varun Sethi <V.Sethi@nxp.com>,
"Rajesh V . Bikkina" <rajesh.bikkina@nxp.com>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Diana Madalina Craciun <diana.craciun@nxp.com>,
netdev <netdev@vger.kernel.org>, Marcin Wojtas <mw@semihalf.com>,
Laurentiu Tudor <laurentiu.tudor@nxp.com>,
Makarand Pawagi <makarand.pawagi@nxp.com>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Pankaj Bansal <pankaj.bansal@nxp.com>,
"David S. Miller" <davem@davemloft.net>,
Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [net-next PATCH v3 4/5] net: phy: Introduce fwnode_get_phy_id()
Date: Fri, 8 May 2020 21:37:55 +0530 [thread overview]
Message-ID: <20200508160755.GB10296@lsv03152.swis.in-blr01.nxp.com> (raw)
In-Reply-To: <83ab4ca4-9c34-4cdd-4413-3b4cdf96727d@arm.com>
On Thu, May 07, 2020 at 02:54:09PM -0500, Jeremy Linton wrote:
> Hi,
>
> On 5/7/20 12:27 PM, Andy Shevchenko wrote:
> > On Thu, May 7, 2020 at 4:26 PM Jeremy Linton <jeremy.linton@arm.com> wrote:
> > > On 5/5/20 8:29 AM, Calvin Johnson wrote:
> >
> > > > + if (sscanf(cp, "ethernet-phy-id%4x.%4x",
> > > > + &upper, &lower) == 2) {
> > > > + *phy_id = ((upper & 0xFFFF) << 16) | (lower & 0xFFFF);
> > > > + return 0;
> > > > + }
> >
> > > Isn't the ACPI _CID() conceptually similar to the DT compatible
> > > property?
> >
> > Where?
>
> Not, sure I understand exactly what your asking. AFAIK, in general the dt
> property is used to select a device driver/etc based on a more to less
> compatible set of substrings. The phy case is a bit different because it
> codes a numerical part number into the string rather than just using
> arbitrary strings to select a driver and device. But it uses that as a
> vendor selector for binding to the correct driver/device.
>
> Rephrasing the ACPI spec, the _CID() is either a single compatible id, or a
> list of ids in order of preference. Each id is either a HID (string or EISA
> type id) or a bus specific string encoding vendor/device/etc. (https://elixir.bootlin.com/linux/v5.7-rc4/source/drivers/acpi/acpica/utids.c#L186).
> One of the examples is "PCI\VEN_vvvv&DEV_dddd"
>
> So that latter case seems to be almost exactly what we have here.
Got your point. Yes, the ACPI spec says the same.
If we are using _CID as a string, then it must be a string that uses a
bus-specific nomenclature. This AFAIU may take the format
"PHY\VEN_IDvvvv&ID_DDDD" as you mentioned below and not
"ethernet-phy-id004d.d072" as used in DT.
So, we need to define it some where in the Linux ACPI Documentation.
I don't see any best place to document this. Any suggestions?
>
> >
> > > It even appears to be getting used in a similar way to
> > > identify particular phy drivers in this case.
> >
> > _CID() is a string. It can't be used as pure number.
> >
>
> It does have a numeric version defined for EISA types. OTOH I suspect that
> your right. If there were a "PHY\VEN_IDvvvv&ID_DDDD" definition, it may not
> be ideal to parse it. Instead the normal ACPI model of exactly matching the
> complete string in the phy driver might be more appropriate.
IMO, it should be fine to parse the string to extract the phy_id. Is there any
reason why we cannot do this?
>
> Similarly to how I suspect the next patch's use of "compatible" isn't ideal
> either, because whether a device is c45 or not, should tend to be fixed to a
> particular vendor/device implementation and not a firmware provided
> property.
I tend to agree with you on this. Even for DT, ideal case, IMO should be:
1) mdiobus_scan scans the mdiobus for c22 devices by reading phy id from
registers 2 and 3
2) if not found scan for c45 devices <= looks like this is missing in Linux
3) look for phy_id from compatible string.
Meanwhile, please note some usage of compatible property in edk2-platforms:
https://github.com/tianocore/edk2-platforms/blob/master/Platform/96Boards/Secure96Dxe/Secure96.asl#L20
https://github.com/tianocore/edk2-platforms/blob/master/Silicon/Marvell/Armada7k8k/AcpiTables/Armada80x0McBin/Dsdt.asl#L280
https://github.com/tianocore/edk2-platforms/blob/master/Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Optee.asl#L17
Regards
Calvin
next prev parent reply other threads:[~2020-05-08 16:08 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 13:29 [net-next PATCH v3 0/5] Introduce new fwnode based APIs to support phylink and phy layers Calvin Johnson
2020-05-05 13:29 ` [net-next PATCH v3 1/5] net: phy: Introduce phy related fwnode functions Calvin Johnson
2020-05-05 14:44 ` Russell King - ARM Linux admin
2020-05-05 23:21 ` kbuild test robot
2020-05-05 23:39 ` Russell King - ARM Linux admin
2020-05-06 0:07 ` kbuild test robot
2020-05-05 13:29 ` [net-next PATCH v3 2/5] net: phy: alphabetically sort header includes Calvin Johnson
2020-05-05 13:29 ` [net-next PATCH v3 3/5] phylink: Introduce phylink_fwnode_phy_connect() Calvin Johnson
2020-05-05 14:13 ` Andy Shevchenko
2020-05-05 14:35 ` Russell King - ARM Linux admin
2020-05-05 13:29 ` [net-next PATCH v3 4/5] net: phy: Introduce fwnode_get_phy_id() Calvin Johnson
2020-05-05 14:15 ` Andy Shevchenko
2020-05-05 14:20 ` Russell King - ARM Linux admin
2020-05-07 13:26 ` Jeremy Linton
2020-05-07 17:27 ` Andy Shevchenko
2020-05-07 19:54 ` Jeremy Linton
2020-05-08 16:07 ` Calvin Johnson [this message]
2020-05-08 18:13 ` Andrew Lunn
2020-05-08 19:18 ` Jeremy Linton
2020-05-08 20:27 ` Andrew Lunn
2020-05-08 22:48 ` Jeremy Linton
2020-05-08 23:42 ` Andrew Lunn
2020-05-09 0:11 ` Jeremy Linton
2020-05-11 8:00 ` Calvin Johnson
2020-05-11 9:38 ` Russell King - ARM Linux admin
2020-05-11 10:29 ` Calvin Johnson
2020-05-11 10:48 ` Russell King - ARM Linux admin
2020-05-11 12:02 ` Calvin Johnson
2020-05-11 13:04 ` Andrew Lunn
2020-05-11 13:35 ` Russell King - ARM Linux admin
2020-05-11 14:59 ` Calvin Johnson
2020-05-11 7:39 ` Calvin Johnson
2020-05-11 5:52 ` Calvin Johnson
2020-05-11 12:53 ` Andrew Lunn
2020-05-05 13:29 ` [net-next PATCH v3 5/5] net: mdiobus: Introduce fwnode_mdiobus_register_phy() Calvin Johnson
2020-05-05 14:22 ` Andy Shevchenko
2020-05-07 7:44 ` Calvin Johnson
2020-05-07 9:10 ` Andy Shevchenko
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