Re: [PATCH] mfd: omap-usb-host: AM3715 OHCI needs 120m functional clock

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Ben Dooks <ben.dooks-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org> [151012 11:22]:
> On 12/10/15 18:45, Tony Lindgren wrote:
> > * Ben Dooks <ben.dooks-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org> [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-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>
> >> ---
> >>  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?
> 
> I don't see that helps enabling the clock. The code decideds if
> no EHCI ports in use that it doesn't need to enable the EHCI fclk.

Right, you need to do clk_prepare_enable() in it first? :)

Tony
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