Re: [PATCH v5 1/2] arm: dts: rockchip: rk3399: usb: ehci: Fix EHCI probe in rk3399 to access peripherals by USB 2.

[Xavier Drudis Ferran <xdrudis@tinet.cat>]

arch/arm/dts/rk3399.dtsi has a node

  usb_host0_ehci: usb@fe380000 {
       compatible = "generic-ehci";

with clocks:

       clocks = <&cru HCLK_HOST0>, <&cru HCLK_HOST0_ARB>,
                <&u2phy0>;

The first 2 refer to nodes with class UCLASS_CLK, but &u2phy0
has class UCLASS_PHY.

  u2phy0: usb2phy@e450 {
       compatible = "rockchip,rk3399-usb2phy";

Since clk_get_bulk() only looks for devices with UCLASS_CLK,
it fails with -ENODEV and then ehci_usb_probe() aborts.

The consequence is peripherals connected to a USB 2 port (e.g. in a
Rock Pi 4 one of the two ports nearer the edge) not being detected.
They're detected if CONFIG_USB_OHCI_GENERIC is selected in Kconfig,
because ohci_usb_probe() does not abort when one clk_get_by_index()
fails, but then they work in USB 1 mode,.

rk3399.dtsi comes from linux and the  u2phy0 was added[1] to the clock
list in:


    commit b5d1c57299734f5b54035ef2e61706b83041f20c
    Author: William wu <wulf@rock-chips.com>
    Date:   Wed Dec 21 18:41:05 2016 +0800

    arm64: dts: rockchip: add u2phy clock for ehci and ohci of rk3399

    We found that the suspend process was blocked when it run into
    ehci/ohci module due to clk-480m of usb2-phy was disabled.
    [...]

Suspend concerns don't apply to U-Boot, and the problem with U-Boot
failing to probe EHCI doesn't apply to linux, because in linux
rockchip_usb2phy_clk480m_register makes u2phy0 a proper clock provider
when called by rockchip_usb2phy_probe().

So I can think of a few alternative solutions:

1- Change ehci_usb_probe() to make it more similar to
   ohci_usb_probe(), and survive failure to get one clock. Looks a
   little harder, and I don't know whether it could break something if
   it ignored a clock that was important for something else than
   suspend. (tried in v2)

2- Change rk3399.dtsi effecttively reverting the linux commit
   b5d1c57299734f5b54035ef2e61706b83041f20c. This dealigns the .dtsi
   from linux and seems fragile at the next synchronisation.

3- Change the clock list in rk3399-u-boot.dtsi or somewhere else.
   This survives .dts* sync but may survive "too much" and miss some
   change from linux that we might want. (tried in v1)

4- Enable CONFIG_USB_OHCI_GENERIC and use the ports in USB 1 mode.
   This would need to be made for all boards using rk3399.  In a
   simple test reading one file from USB storage it gave 769.5 KiB/s
   instead of 20.5 MiB/s with solution 2.

5- Trying to replicate linux and have usb2phy somehow provide a clk,
   or have a separate clock device for usb2phy in addition to the phy
   device. (tried in v3 and this v5, v4 did it wrong)

This series is a third attempt to implement option 5 as Marek Vasut
requested in December 5th.  Options 1 and 3 didn't get through[2,3].

The first patch in the series (identical to v3) just registers usb2phy
as a clock driver, without any specific operations, so that
ehci-generic.c finds it and is happy. It worked in my tests on a Rock
Pi 4 B+ (rk3399).

Since Marek Vasut objected to an operationless driver[4], the second
patch adds enable and disable operations adapted from linux prepare
and unprepare operations (and round_rate(), which doesn't seem very
useful anyway since it's a fixed clock). Since there're no users of
this clock in u-boot, I can't see any difference in my tests with only
the first patch or both, so I can't be sure it really works if it's
ever needed, but it's hopefully more complete.

Link: [1] https://lkml.kernel.org/lkml/1731551.Q6cHK6n5ZM@phil/T/

Cc: Simon Glass <sjg@chromium.org>
Cc: Philipp Tomsich <philipp.tomsich@vrull.eu>
Cc: Kever Yang <kever.yang@rock-chips.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Sean Anderson <seanga2@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Christoph Fritz <chf.fritz@googlemail.com>

Signed-off-by: Xavier Drudis Ferran <xdrudis@tinet.cat>
---
 drivers/phy/rockchip/phy-rockchip-inno-usb2.c | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
index b32a498ea7..9769ada376 100644
--- a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
+++ b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
@@ -7,7 +7,7 @@
  */
 
 #include <common.h>
-#include <clk.h>
+#include <clk-uclass.h>
 #include <dm.h>
 #include <asm/global_data.h>
 #include <dm/device_compat.h>
@@ -168,6 +168,9 @@ static struct phy_ops rockchip_usb2phy_ops = {
 	.of_xlate = rockchip_usb2phy_of_xlate,
 };
 
+static struct clk_ops rockchip_usb2phy_clk_ops = {
+};
+
 static int rockchip_usb2phy_probe(struct udevice *dev)
 {
 	struct rockchip_usb2phy *priv = dev_get_priv(dev);
@@ -240,6 +243,18 @@ static int rockchip_usb2phy_bind(struct udevice *dev)
 		}
 	}
 
+	if (!ret) {
+		node = dev_ofnode(dev);
+		name = ofnode_get_name(node);
+		dev_dbg(dev, "clk for node %s\n", name);
+		ret = device_bind_driver_to_node(dev, "rockchip_usb2phy_clock",
+						 name, node, &usb2phy_dev);
+		if (ret) {
+			dev_err(dev,
+				"'%s' cannot bind 'rockchip_usb2phy_clock'\n", name);
+		}
+	}
+
 	return ret;
 }
 
@@ -303,6 +318,12 @@ U_BOOT_DRIVER(rockchip_usb2phy_port) = {
 	.ops		= &rockchip_usb2phy_ops,
 };
 
+U_BOOT_DRIVER(rockchip_usb2phy_clock) = {
+	.name		= "rockchip_usb2phy_clock",
+	.id		= UCLASS_CLK,
+	.ops		= &rockchip_usb2phy_clk_ops,
+};
+
 U_BOOT_DRIVER(rockchip_usb2phy) = {
 	.name	= "rockchip_usb2phy",
 	.id	= UCLASS_PHY,
-- 
2.20.1