Date:	Thu, 13 Oct 2011 17:19:11 +0530
From:	"Munegowda, Keshava" <keshava_mgowda@...com>
To:	t-kristo@...com
Cc:	Paul Walmsley <paul@...an.com>,
	"Cousson, Benoit" <b-cousson@...com>,
	"Basak, Partha" <p-basak2@...com>, "Balbi, Felipe" <balbi@...com>,
	parthab@...ia.ti.com, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Gadiyar, Anand" <gadiyar@...com>, sameo@...ux.intel.com,
	tony@...mide.com, "Hilman, Kevin" <khilman@...com>,
	johnstul@...ibm.com, "Sripathy, Vishwanath" <vishwanath.bs@...com>
Subject: Re: [PATCH 2/5 v11] arm: omap: usb: ehci and ohci hwmod structures
 for omap3

On Thu, Oct 13, 2011 at 4:58 PM, Tero Kristo <t-kristo@...com> wrote:
> On Thu, 2011-10-13 at 09:12 +0200, Munegowda, Keshava wrote:
>> On Tue, Sep 27, 2011 at 6:48 PM, Munegowda, Keshava
>> <keshava_mgowda@...com> wrote:
>> > On Tue, Sep 27, 2011 at 6:12 PM, Tero Kristo <t-kristo@...com> wrote:
>> >> On Tue, 2011-09-27 at 08:04 +0200, Basak, Partha wrote:
>> >>> >
>> >> Texas Instruments Oy, Tekniikantie 12, 02150 Espoo. Y-tunnus: 0115040-6. Kotipaikka: Helsinki
>> >>
>> >>
> Texas Instruments Oy, Porkkalankatu 22, 00180 Helsinki, Finland. Business ID: 0115040-6. Domicile: Helsinki
>
> -----Original Message-----
>
>> >>
>> >>> >From: Munegowda, Keshava [mailto:keshava_mgowda@...com]
>> >>> >Sent: Monday, September 26, 2011 7:49 PM
>> >>> >To: Paul Walmsley; Tero Kristo; b-cousson@...com; balbi@...com;
>> >>> >parthab@...ia.ti.com
>> >>> >Cc: linux-usb@...r.kernel.org; linux-omap@...r.kernel.org; linux-
>> >>> >kernel@...r.kernel.org; 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 Sat, Sep 24, 2011 at 12:00 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:
>> >>> >>>
>> >>> >>> But the question arises here , why do we need these ehci and ohci as
>> >>> >two
>> >>> >>> different hwmods containing only irq and base address? It is required
>> >>> >>> for future - to implement remote wakeup feature for ehci and ohci
>> >>> >ports
>> >>> >>> depending on irq-chain handler patches by Tero. Separate hwmods for
>> >>> >ehci
>> >>> >>> and ohci are needed to enable prcm chain-handler to uniquely identify
>> >>> >>> the wakeup source as ehci or ohci and call only the corresponding
>> >>> >>> interrupt handler. We will be using omap_hwmod_mux_init for ehci and
>> >>> >>> ohci hwmods to enable I/O wakeup capability for respective IO-pads.
>> >>> >>> Depending on the particular wakeup source(ehci/ohci), the
>> >>> >corresponding
>> >>> >>> ehci or ohci irq handler will be called.
>> >>> >>>
>> >>> >>> If ehci and ohci are combined with usbhs hwmod as a single hwmod ,
>> >>> >then
>> >>> >>> for every wakeup (either ehci or ohci port wakeup) only the first
>> >>> >>> interrupt handler will be called (please look at the function
>> >>> >>> omap_hwmod_mux_handle_irq of
>> >>> >>>
>> >>> >>> /arch/arm/mach-omap2/mux.c file ; in tero's latest patch:
>> >>> >>> http://www.mail-archive.com/linux-omap@vger.kernel.org/msg53139.html)
>> >>> >>> , so in this
>> >>> >>> case, if ehci interrupt is the first interrupt , then even for ohci
>> >>> >wakeup
>> >>> >>> , only ehci interrupt will get called; which will break the
>> >>> >functionality.
>> >>> >>
>> >>> >> Any reason why this couldn't be handled either by:
>> >>> >>
>> >>> >> 1. adding an IRQ number field to struct omap_hwmod_mux_info, and
>> >>> >changing
>> >>> >> _omap_hwmod_mux_handle_irq() to raise that IRQ number?
>> >>> >
>> >>> >
>> >>> >yes, it is possible by changing the existing irq-chain handler by tero
>> >>> >Kristo
>> >>> >
>> >>> >I am looping tero too.
>> >>> >
>> >>> >So here are new requirements for the irq-chain handler
>> >>> >
>> >>> >1. The hwmod should have have option to have multiple mux structures
>> >>> >
>> >>> >This is something like:
>> >>> >
>> >>> >The existing mux structure definition in omap_hwmod [file:
>> >>> >/arch/arm/plat-omap/include/plat/omap_hwmod.h ] structure
>> >>> >
>> >>> >     struct omap_hwmod_mux_info      *mux;
>> >>> >
>> >>> >it should changed to
>> >>> >
>> >>> >     struct omap_hwmod_mux_info      **pmux;
>> >>> >         U32                                            mux_cnt;
>> >>> >
>> >>> >
>> >>> >pmux - pointers to mux ; array of mux structures.
>> >>> >mux_cnt - number of mux per hwmod.
>> >>> >
>> >>> >
>> >>> >2. The mux  omap_hwmod_mux_info  structure should have new member
>> >>> >called irq, like as follows:
>> >>> >
>> >>> >struct omap_hwmod_mux_info {
>> >>> >     int                             nr_pads;
>> >>> >     ...
>> >>> >        ....
>> >>> >        u32                           irq;
>> >>> >
>> >>> >};
>> >>> >
>> >>> >Upon wakeup of the I/O pad of the mux , the irq-chain handler should
>> >>> >invoke the irq handler of the irq numbered <map_hwmod_mux_info.irq>
>> >>> >
>> >>> >3.  There should be "SOME WAY" to supply the irqs  from hwmod
>> >>> >structure (omap_hwmod) to mux structure (omap_hwmod_mux_info)
>> >>> >
>> >>> >
>> >>> >if you , tero and other opensource people are aligned on the proposed
>> >>> >changes on the irq-handler ;
>> >>> >then it is possible to have two hwmods ( usbhs and tll) for usbhost
>> >>> >driver.
>> >>> >please let me know you comments on the above approach.
>> >>> >
>> >>>
>> >>> Hello Tero,
>> >>>
>> >>> I would like to draw your attention to the following thread:
>> >>>
>> >>> We need to support the following:
>> >>> 1. Ability to associate multiple mux info to a hwmod.
>> >>> 2. Able to associate a particular irq handler to a mux info.
>> >>> 3. PRCM Chain handler should loop through all mux-info arrays
>> >>>    for a particular hwmod to identify the possible wakeup source(s)
>> >>>    and call the appropriate irq handler for that mux-info.
>> >>>    (It is possible that both mux-info are woken up in which case both
>> >>> handlers should be called).
>> >>>
>> >>> To give you a little more perspective, EHCI & OHCI are co-controllers
>> >>> under UHH/TLL.
>> >>> They do not get presented separately to the OCP bus, hence do not qualify
>> >>> as separate hwmods
>> >>> (Paul had objected to the design approach representing EHCI & OHCI as
>> >>> different hwmods).
>> >>>
>> >>> However, we need a mechanism to efficiently identify/distinguish
>> >>> remote-wakeup, connect/disconnect
>> >>> On to an EHCI port vs an OHCI port & call only the correct interrupt
>> >>> handler(EHCI or OHCI).
>> >>>
>> >>>  To incorporate this, chain handler implementation would need some
>> >>> enhancements.
>> >>>  We can look into the details in the next merge window cycle in
>> >>> conjunction with aggressive clock management support for EHCI/OHCI.
>> >>>  But fundamentally, if you are aligned to the approach, we can go ahead
>> >>> collapsing the EHCI & OHCI hwmods into one.
>> >>
>> >> Hi,
>> >>
>> >> So, you would need a mechanism to do something like this:
>> >>
>> >> pad a or b wakeup detected -> irq0
>> >> pad c or d wakeup detected -> irq1?
>> >
>> > yes, if get something like this , its perfect.
>>
>> Hi Tero
>>            Are you posting the patches with these changes?
>> please let me know when you will be able to post the patches.
>> so that I start the design of usb host remote wakeup using your changes.
>>
>> regards
>> keshava
>>
>
> Sorry for the delay, but I am still not quite sure how this should be
> handled for upstream. Attached is a proposal hack patch that should
> work, you can at least try it out to see what happens. It applies on top
> of my latest PRCM chain handler set (version 9.) Patch desc contains a
> guide how to use it.
>
> -Tero


Thanks tero,
          we are still in the internal design discussion of usbhs remote wakeup.
but, we are looking for the upstreamable code.
I request please send it as formal patch so that we will align with
Paul, benoit, kevin
Felipe and all other USB and PM experts.

regards
keshava
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