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

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Date:	Mon, 26 Sep 2011 19:49:23 +0530
From:	"Munegowda, Keshava" <keshava_mgowda@...com>
To:	Paul Walmsley <paul@...an.com>, Tero Kristo <t-kristo@...com>,
	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.


>
> or
>
> 2. using shared interrupts?
>
>
> - Paul
>
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