From: Grant Likely <grant.likely@arm.com>
To: Andrew Lunn <andrew@lunn.ch>, Arnd Bergmann <arnd@arndb.de>
Cc: Calvin Johnson <calvin.johnson@oss.nxp.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Jeremy Linton <jeremy.linton@arm.com>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Jon <jon@solid-run.com>,
Cristi Sovaiala <cristian.sovaiala@nxp.com>,
Ioana Ciornei <ioana.ciornei@nxp.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Madalin Bucur <madalin.bucur@oss.nxp.com>,
Networking <netdev@vger.kernel.org>,
linux.cj@gmail.com,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
nd <nd@arm.com>
Subject: Re: [net-next PATCH v7 1/6] Documentation: ACPI: DSD: Document MDIO PHY
Date: Tue, 29 Sep 2020 16:59:41 +0100 [thread overview]
Message-ID: <28906ffc-8774-6479-b292-e8ab2c6f5434@arm.com> (raw)
In-Reply-To: <20200929145910.GJ3950513@lunn.ch>
On 29/09/2020 15:59, Andrew Lunn wrote:
>> IIRC both UEFI and ACPI define only little-endian data structures.
>> The code does not attempt to convert these into CPU endianness
>> at the moment. In theory it could be changed to support either, but
>> this seems non-practical for the UEFI runtime services that require
>> calling into firmware code in little-endian mode.
>
> Hi Arnd
>
> Thanks for the info. So we can assume the CPU is little endian. That
> helps narrow down the problem.
>
>>> If this is the bus controller endianness, are all the SoCs you plan to
>>> support via ACPI the same endianness? If they are all the same, you
>>> can hard code it.
>>
>> NXP has a bunch of SoCs that reuse the same on-chip devices but
>> change the endianness between them based on what the chip
>> designers guessed the OS would want, which is why the drivers
>> usually support both register layouts and switch at runtime.
>> Worse, depending on which SoC was the first to get a DT binding
>> for a particular NXP on-chip device, the default endianness is
>> different, and there is either a "big-endian" or "little-endian"
>> override in the binding.
>>
>> I would guess that for modern NXP chips that you might boot with
>> ACPI the endianness is always wired the same way, but I
>> understand the caution when they have been burned by this
>> problem before.
>
> So it might depend on if NXP is worried it might flip the endianness
> of the synthesis of the MDIO controller at some point for devices it
> wants to support using ACPI?
>
> Does ACPI have a standard way of declaring the endianness of a device?
> We don't really want to put the DT parameter in ACPI, we want to use
> the ACPI way of doing it.
No, and it doesn't need one. If a device is wired up big-endian, then it
is between the device driver and the device. The OS, and the ACPI
framework doesn't come into play other than providing a generic way of
encoding data useful to the device driver. Encoding endian hasn't been a
common problem, and the tools are already there to deal with it when it is.
g.
next prev parent reply other threads:[~2020-09-29 16:00 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 9:03 [net-next PATCH v7 0/6] ACPI support for dpaa2 MAC driver Calvin Johnson
2020-07-15 9:03 ` [net-next PATCH v7 1/6] Documentation: ACPI: DSD: Document MDIO PHY Calvin Johnson
2020-07-16 3:04 ` Florian Fainelli
2020-07-16 3:11 ` Andrew Lunn
2020-07-23 23:26 ` Jeremy Linton
2020-07-24 13:39 ` Andrew Lunn
2020-07-24 17:26 ` Jeremy Linton
2020-07-24 17:39 ` Florian Fainelli
2020-07-24 19:20 ` Andrew Lunn
2020-07-24 20:12 ` Andy Shevchenko
2020-07-24 20:13 ` Florian Fainelli
2020-07-24 20:20 ` Andy Shevchenko
2020-07-25 7:36 ` Calvin Johnson
2020-07-25 10:48 ` Andy Shevchenko
2020-07-24 21:06 ` Russell King - ARM Linux admin
2020-07-27 17:03 ` Sudeep Holla
2020-07-24 19:14 ` Andrew Lunn
2020-07-27 17:21 ` Sudeep Holla
2020-07-28 20:34 ` Andrew Lunn
2020-07-28 20:59 ` Russell King - ARM Linux admin
2020-07-28 21:26 ` Andy Shevchenko
2020-07-29 16:00 ` Rafael J. Wysocki
2020-07-31 15:08 ` Andrew Lunn
2020-07-27 17:32 ` Jon Nettleton
[not found] ` <1595922651-sup-5323@galangal.danc.bne.opengear.com>
2020-07-28 20:45 ` Andrew Lunn
2020-07-28 20:56 ` Florian Fainelli
2020-07-28 21:28 ` Andy Shevchenko
2020-07-28 21:40 ` Florian Fainelli
2020-07-31 15:14 ` Andrew Lunn
2020-09-25 13:22 ` Grant Likely
2020-07-28 22:30 ` Jeremy Linton
2020-07-29 0:39 ` Florian Fainelli
2020-07-29 2:53 ` Jeremy Linton
2020-07-29 3:16 ` Florian Fainelli
2020-07-29 8:43 ` Jon Nettleton
2020-07-29 9:39 ` Calvin Johnson
2020-09-25 13:34 ` Grant Likely
2020-09-26 4:30 ` Calvin Johnson
2020-09-29 5:17 ` Calvin Johnson
2020-09-29 13:43 ` Andrew Lunn
2020-09-29 13:55 ` Andy Shevchenko
2020-09-29 14:32 ` Andrew Lunn
2020-09-29 14:46 ` Andy Shevchenko
2020-09-29 15:06 ` Andrew Lunn
2020-09-29 15:29 ` Arnd Bergmann
2020-09-29 14:44 ` Arnd Bergmann
2020-09-29 14:59 ` Andrew Lunn
2020-09-29 15:59 ` Grant Likely [this message]
2020-09-29 15:53 ` Grant Likely
2020-09-29 16:04 ` Calvin Johnson
2020-07-15 9:03 ` [net-next PATCH v7 2/6] net: phy: introduce device_mdiobus_register() Calvin Johnson
2020-07-16 3:05 ` Florian Fainelli
2020-07-15 9:03 ` [net-next PATCH v7 3/6] net/fsl: use device_mdiobus_register() Calvin Johnson
2020-07-16 3:05 ` Florian Fainelli
2020-07-15 9:03 ` [net-next PATCH v7 4/6] net: phy: introduce phy_find_by_mdio_handle() Calvin Johnson
2020-07-16 3:06 ` Florian Fainelli
2020-07-15 9:03 ` [net-next PATCH v7 5/6] phylink: introduce phylink_fwnode_phy_connect() Calvin Johnson
2020-07-15 9:04 ` [net-next PATCH v7 6/6] net: dpaa2-mac: Add ACPI support for DPAA2 MAC driver Calvin Johnson
2020-09-25 13:39 ` [net-next PATCH v7 0/6] ACPI support for dpaa2 " Grant Likely
2020-09-26 4:34 ` Calvin Johnson
2020-07-25 14:23 Calvin Johnson
2020-07-25 14:23 ` [net-next PATCH v7 1/6] Documentation: ACPI: DSD: Document MDIO PHY Calvin Johnson
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