[U-Boot] [PATCH] sunxi: H3/H5/A64: OHCI: prevent turning off shared gates

[Andre Przywara]

The USB host controllers on the H3, H5 and A64 have the oddity of
sharing some clock and reset gates, so both the OHCI and EHCI bits have
to be enabled to make only one of them working. We take care of this, and
initialisation works fine (due to setting already set bits).
However on shutdown we turn the clocks and reset gates off already when
deregistering one controller, so the other one is no longer functional.
In the result U-Boot complains just before launching the kernel and
then hangs.
Fix this by not turning off the clocks and resets on the OHCI side, so
that the EHCI controller has a chance to properly shut down.
This still isn't perfect, but at least prevents the hang.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
Hi,

commit b62cdbddedc3 ("sunxi: clock: Fix EHCI and OHCI clocks on A64")
introduced the proper reset and clock gates for the A64. While the patch
itself is correct, it broke Linux as soon as one actually enables USB0 in
the DT (in the moment we keep this "disabled" in U-Boot's DT version).

I understand that this patch here is somewhat of a hack, but the proper
ref-counting is not easy to implement between the separate EHCI and OHCI
drivers. Those two files are doomed anyway, since driver model clocks
and reset drivers are already on the horizon:
https://github.com/apritzel/u-boot/commits/sunxi-dm-WIP
So lets fix this up for now so that we can use the Linux kernel DTs with
U-Boot itself.

Cheers,
Andre.

 drivers/usb/host/ohci-sunxi.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/ohci-sunxi.c b/drivers/usb/host/ohci-sunxi.c
index 0ddbdbe460..42ffb6cbcb 100644
--- a/drivers/usb/host/ohci-sunxi.c
+++ b/drivers/usb/host/ohci-sunxi.c
@@ -128,10 +128,18 @@ static int ohci_usb_remove(struct udevice *dev)
 	if (ret)
 		return ret;
 
-	if (priv->cfg->has_reset)
-		clrbits_le32(priv->reset0_cfg, priv->ahb_gate_mask);
-	clrbits_le32(&priv->ccm->usb_clk_cfg, priv->usb_gate_mask);
-	clrbits_le32(&priv->ccm->ahb_gate0, priv->ahb_gate_mask);
+	/*
+	 * For those SoCs that share the clock and reset gates with the EHCI
+	 * controller, we should not turn them off here, to prevent the
+	 * other one hanging (when the EHCI driver tries to shut itself down).
+	 */
+	if (!priv->cfg->extra_ahb_gate_mask) {
+		if (priv->cfg->has_reset)
+			clrbits_le32(priv->reset0_cfg, priv->ahb_gate_mask);
+		clrbits_le32(&priv->ccm->ahb_gate0, priv->ahb_gate_mask);
+	}
+	if (!priv->cfg->extra_usb_gate_mask)
+		clrbits_le32(&priv->ccm->usb_clk_cfg, priv->usb_gate_mask);
 
 	return 0;
 }
-- 
2.14.4