The AM3715 OHCI controller will not function without the EHCI
unit's 120m fclk being enabled. If all the ports in the system
are set to OHCI then the 120m_fclk will not get enabled and no
devices are detected.
Add a new (optional) property to signal the system must enable
the 120m_fck for OHCI so that if no EHCI ports are signalled
then the 120m_fclk should be enabled.
We have found no information about why this is necessary, but
it is suspected the EHCI controller does not complete the initial
reset sequence and therefore does not hand control of the USB
port back.
Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx>
---
Documentation/devicetree/bindings/usb/omap-usb.txt | 3 +++
drivers/mfd/omap-usb-host.c | 4 ++++
2 files changed, 7 insertions(+)
diff --git a/Documentation/devicetree/bindings/usb/omap-usb.txt b/Documentation/devicetree/bindings/usb/omap-usb.txt
index 38d9bb8..fb5fea5 100644
--- a/Documentation/devicetree/bindings/usb/omap-usb.txt
+++ b/Documentation/devicetree/bindings/usb/omap-usb.txt
@@ -23,6 +23,9 @@ OMAP MUSB GLUE
Optional properties:
- ctrl-module : phandle of the control module this glue uses to write to
mailbox
+ - ti,ohci-needs-120m-fck : bool, enable the 120m ehci clock even if just
+ using ohci. Needed for AM3517 in OHCI only mode.
+
SOC specific device node entry
usb_otg_hs: usb_otg_hs@4a0ab000 {
diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
index 1d924d1..13880cf 100644
--- a/drivers/mfd/omap-usb-host.c
+++ b/drivers/mfd/omap-usb-host.c
@@ -680,6 +680,10 @@ static int usbhs_omap_probe(struct platform_device *pdev)
need_logic_fck |= true;
}
+ /* The AM3517 requries the 120m-fck active to allow the OHCI to work */
+ if (of_property_read_bool(dev->of_node, "ti,ohci-needs-120m-fck"))
+ need_logic_fck |= true;
+
if (need_logic_fck) {
omap->ehci_logic_fck = devm_clk_get(dev,
"usbhost_120m_fck");
--
2.6.1
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