Hi Marek,

kabel@kernel.org wrote on Thu, 28 Oct 2021 20:42:38 +0200:

From: Pali Rohár <pali@kernel.org>

Remove old RPC implementation and add a new native kernel implementation.

The old implementation uses ARM SMC API to issue RPC calls to ARM Trusted
Firmware which provides real implementation of PHY configuration.

But older versions of ARM Trusted Firmware do not provide this PY
configuration functionality, simply returning: operation not supported; or
worse, some versions provide the configuration functionality incorrectly.

For example the firmware shipped in ESPRESSObin board has this older
version of ARM Trusted Firmware and therefore SATA, USB 3.0 and PCIe
functionality do not work with newer versions of Linux kernel.

Due to the above reasons, the following commits were introduced into Linux,
to workaround these issues by ignoring -EOPNOTSUPP error code from
phy-mvebu-a3700-comphy driver function phy_power_on():

commit 45aefe3d2251 ("ata: ahci: mvebu: Make SATA PHY optional for Armada
3720")
commit 3241929b67d2 ("usb: host: xhci: mvebu: make USB 3.0 PHY optional for
Armada 3720")
commit b0c6ae0f8948 ("PCI: aardvark: Fix initialization with old Marvell's
Arm Trusted Firmware")

Replace this RPC implementation with proper native kernel implementation,
which is independent on the firmware. Never return -EOPNOTSUPP for proper
arguments.

This should solve multiple issues with real-world boards, where it is not
possible or really inconvenient to change the firmware. Let's eliminate
these issues.

This implementation is ported directly from Armada 3720 comphy driver found
in newest version of ARM Trusted Firmware source code.

I think we should not opt for a status quo and let broken users out
there. It is true that reflashing the firmware can be challenging in
some situations, so let's jump 3 years back and re-integrate that code
in the kernel.

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---

Thanks,
Miquèl

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