From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roger Quadros Subject: Re: [PATCH] mfd: omap-usb-host: AM3715 OHCI needs 120m functional clock Date: Tue, 13 Oct 2015 11:45:59 +0300 Message-ID: <561CC4C7.8020408@ti.com> References: <1444671232-10253-1-git-send-email-ben.dooks@codethink.co.uk> <20151012174505.GJ23801@atomide.com> <561BF97B.2010501@codethink.co.uk> <20151012191948.GM23801@atomide.com> <561CBF7F.7020705@codethink.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <561CBF7F.7020705-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ben Dooks , Tony Lindgren Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, linux-kernel-81qHHgoATdFT9dQujB1mzip2UmYkHbXO@public.gmane.org List-Id: linux-omap@vger.kernel.org Ben, On 13/10/15 11:23, Ben Dooks wrote: > On 12/10/15 20:19, Tony Lindgren wrote: >> * Ben Dooks [151012 11:22]: >>> On 12/10/15 18:45, Tony Lindgren wrote: >>>> * Ben Dooks [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 >>>>> --- >>>>> 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? :) > > No, if that was the case the driver would never work for the EHCI case. > > The issue is: > > 1) All ports on the system are set to OHCI > 2) The omap-usb-host.c does not touch usbhost_120m_fck if no EHCI ports > 3) The OHCI fails to detect any devices due to point 2. > Instead of your existing approach why not just modify the preceeding if condition that sets need_logic_fck to suit the OHCI case. That way you don't need to add a new DT binding. The old assumption was that 120m_fck logic clock is only needed for EHCI mode but it looks like OHCI mode needs it as well. You should also rename omap->ehci_logic_fck to omap->hci_logic_fck as it is no longer ehci specific. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html