RE: [PATCH] select NOP_USB_XCEIV for OMAP4

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Anders, David wrote:
> > -----Original Message-----
> > From: Gadiyar, Anand
> > Sent: Wednesday, June 23, 2010 6:03 PM
> > To: Koen Kooi; Kevin Hilman; Hunter, Jon
> > Cc: Anders, David; linux-usb@xxxxxxxxxxxxxxx; linux-omap@xxxxxxxxxxxxxxx;
> > Gupta, Ajay Kumar; felipe.balbi@xxxxxxxxx
> > Subject: RE: [PATCH] select NOP_USB_XCEIV for OMAP4
> > 
> > Koen Kooi wrote:
> > > Op 23 jun 2010, om 22:33 heeft Kevin Hilman het volgende geschreven:
> > > > David Anders <x0132446@xxxxxx> writes:
> > > >
> > > >> Add select statement to force selection of NOP_USB_XCEIV for OMAP4.
> > > >>
> > > >> Signed-off-by: David Anders <x0132446@xxxxxx>
> > > >> ---
> > > >> drivers/usb/musb/Kconfig |    1 +
> > > >> 1 files changed, 1 insertions(+), 0 deletions(-)
> > > >>
> > > >> diff --git a/drivers/usb/musb/Kconfig b/drivers/usb/musb/Kconfig
> > > >> index cfd38ed..e4624bc 100644
> > > >> --- a/drivers/usb/musb/Kconfig
> > > >> +++ b/drivers/usb/musb/Kconfig
> > > >> @@ -11,6 +11,7 @@ config USB_MUSB_HDRC
> > > >> 	depends on (USB || USB_GADGET)
> > > >> 	depends on (ARM || (BF54x && !BF544) || (BF52x && !BF522 && !BF523))
> > > >> 	select NOP_USB_XCEIV if (ARCH_DAVINCI || MACH_OMAP3EVM || BLACKFIN)
> > > >> +	select NOP_USB_XCEIV if ARCH_OMAP4
> > > >> 	select TWL4030_USB if MACH_OMAP_3430SDP
> > > >> 	select USB_OTG_UTILS
> > > >> 	tristate 'Inventra Highspeed Dual Role Controller (TI, ADI, ...)'
> > > >
> > > > Shouldn't this be a board-specific option, and not set for every
> > > > OMAP4-based config?
> > >
> > > If that's true, why do the  davinci and blackfin archs force it?
> > >
> > 
> > Kevin's right. For OMAP4 at least, this is something that is probably'
> > best left up to the board to select.
> > 
> > For the davinci's and blackfins, they don't have an option. They have
> > a fully transparent internal PHY which doesn't need any configuring.
> > 
> > 
> > However, with the OMAP4, you could potentially use an external ULPI transceiver.
> > This can be another transparent PHY for which we could select the NOP_XCEIV.
> > Or it could be something like the PHY in the TWL5030 which may need configuring
> > over an I2C interface.
> > 
> > 
> > - Anand
> 
> Normally I would agree with you, however there are a number 
> of items that I would like to iterate:
> 
> 1. 100% of the currently known OMAP4 platforms use the NOP, 
> wouldn't it be easier to add an exception if/when one exists 
> rather than add each individual board that does require the NOP?
> 
> 2. Including the NOP does not preclude the usage of another 
> transceiver, simply don't register the NOP in your machine file.
> 
> 3. The omap3_defconfig already has the NOP enabled. If we are 
> pushing towards a unified defconfig for omap2/3/4, then the 
> NOP will be enabled anyway. Linus is already pushing for more 
> decisions to be made directly in the Kconfig and consoldation 
> of defconfigs(and/or removal of them).
> 
> 4. The NOP will need to be enabled if we intend to truly push 
> for a "Multi-Boot" image that will boot multiple omap3 and 
> omap4 platforms. For example if we have a kernel image that 
> is intended to boot the 4430sdp, blaze, panda, and 
> board-X(with an external transceiver), NOP is going to be 
> included anyway.
> 
> 
> If the community in general is going to push for consolidated 
> defconfigs, more robust decision making in Kconfig, and 
> Multi-Boot support, then the way we thinking about what goes 
> into Kconfig will have to change as well.
> 
> 

I see what you mean. Agree with all your points. Having the NOP_XCEIV
selected doesn't prevent us from using an external PHY as long
as the board file doesn't register a NOP_XCEIV.

- Anand
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