* Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> [151012 10:38]:
> 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");
Hmm why not just use the standard device tree clocks property and then do
clk_get_rate() on the clock?
Regards,
Tony
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