linux-kernel - Re: [PATCH 2/5 v11] arm: omap: usb: ehci and ohci hwmod structures for omap3

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Date:	Wed, 28 Sep 2011 17:38:47 +0530
From:	"Munegowda, Keshava" <keshava_mgowda@...com>
To:	Paul Walmsley <paul@...an.com>, Benoit Cousson <b-cousson@...com>
Cc:	parthab@...ia.ti.com, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	balbi@...com, gadiyar@...com, sameo@...ux.intel.com,
	tony@...mide.com, khilman@...com, johnstul@...ibm.com,
	vishwanath.bs@...com
Subject: Re: [PATCH 2/5 v11] arm: omap: usb: ehci and ohci hwmod structures
 for omap3

On Mon, Sep 26, 2011 at 8:15 PM, Paul Walmsley <paul@...an.com> wrote:
> On Mon, 26 Sep 2011, Munegowda, Keshava wrote:
>
>> On Sat, Sep 24, 2011 at 12:45 PM, Paul Walmsley <paul@...an.com> wrote:
>> > On Fri, 23 Sep 2011, Munegowda, Keshava wrote:
>> >
>> >> On Thu, Sep 22, 2011 at 11:31 PM, Paul Walmsley <paul@...an.com> wrote:
>> >> >
>> >> > On Thu, 22 Sep 2011, Keshava Munegowda wrote:
>> >> >> 4. usb_tll_hs hwmod of usbhs with the TLL base address and irq.
>> >> >>
>> >> >> Signed-off-by: Keshava Munegowda <keshava_mgowda@...com>
>> >> >> Reviewed-by: Partha Basak <parthab@...ia.ti.com>
>> >> >> ---
>> >> >>  arch/arm/mach-omap2/omap_hwmod_3xxx_data.c |  271 ++++++++++++++++++++++++++++
>> >> >>  1 files changed, 271 insertions(+), 0 deletions(-)
>> >> >>
>> >> >> diff --git a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
>> >> >> index 59fdb9f..d79f728 100644
>> >> >> --- a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
>> >> >> +++ b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
>> >
>> >> >> +static struct omap_hwmod_ocp_if omap34xx_f128m_cfg__usb_host_hs = {
>> >> >> +     .clk            = "usbhost_120m_fck",
>> >> >
>> >> > This doesn't look right.  This is an interface structure record, so it
>> >> > should be associated with an interface clock.  Is the hardware really
>> >> > using the functional clock as the interface clock?  Or, as seems more
>> >> > likely...
>> >>
>> >>
>> >> Agreed, how about:
>> >>
>> >> main clock: usbhost_120m_fck
>> >> optional f clock: usbhost_48m_fck
>> >
>> > Assuming the interface clock is enabled, which one of these clocks is
>> > needed for UHH register accesses to complete successfully?
>>
>> it is usbhost_48m_fck ;
>> so,
>> main clock: usbhost_48m_fck
>> optional clock : usbhost_120m_fck
>>
>> do you agree?
>
> Yes.

Thanks paul,

But In USB Host case, there is a challenge!

I need both usbhost_48m_fck and usbhost_120m_fck to be turned on when
I invoke pm_runtime_get_sync ; so there are couple of options to do this

1. use clk_get with hard coded  usbhost_120m_fck name in  usbhs driver
       enable this clock after invoking pm_runtime_get_sync

2. add an additional flag in hwmod ; so that pm_runtime_get_sync will enable
           main clock as well as optional clocks

please comment on these two approaches..


regards
keshava
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