From: "Dale Farnsworth" <dale@farnsworth•org>
To: Valentine Barshak <vbarshak@ru•mvista.com>
Cc: Linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] PowerPC 440EPx Sequoia USB OHCI DTS entry
Date: Wed, 24 Oct 2007 07:10:41 -0700 [thread overview]
Message-ID: <20071024141041.GA13586@xyzzy.farnsworth.org> (raw)
In-Reply-To: <471F4C53.1070506@ru.mvista.com>
On Wed, Oct 24, 2007 at 05:44:51PM +0400, Valentine Barshak wrote:
> Dale Farnsworth wrote:
> >On Wed, Oct 24, 2007 at 03:19:14PM +0400, Valentine Barshak wrote:
> >>Dale Farnsworth wrote:
> >>>Valentine wrote:
> >>>>Actually I also don't see much reason for the
> >>>>USB_OHCI_HCD_PPC_OF_BE/USB_OHCI_HCD_PPC_OF_LE stuff.
> >>>>Is this really needed?
> >>>I think so. The SOC host controllers are BE and the PCI
> >>>host controllers are LE. Or, do you have an alternative
> >>>method of handling both types?
> >>Yes, PCI controllers are LE, but do we really need user-selectable
> >>USB_OHCI_HCD_PPC_OF_LE option, since USB_OHCI_LITTLE_ENDIAN is selected
> >>by default for USB_OHCI_HCD_PCI?
> >>The USB_OHCI_HCD_PPC_OF_LE/BE stuff is related to PPC OF glue only.
> >>I think it's useless. We should always enable
> >>USB_OHCI_BIG_ENDIAN_DESC and USB_OHCI_BIG_ENDIAN_MMIO for PPC OF
> >>and the real LE/BE implementation should be selected by the
> >>corresponding properties in the device tree.
> >
> >I agree that they don't need to be user selectable. It is far preferable
> >to deduce their values from existing information, if possible.
> >
> >-Dale
>
> This is the original thread:
> http://ozlabs.org/pipermail/linuxppc-embedded/2006-November/025054.html
>
> I think the USB_OHCI_HCD_PPC_OF_LE/BE should be removed.
> We can't avoid the slight overhead even using these options, since
> USB_OHCI_BIG_ENDIAN_MMIO/DESC should always be anabled for PPC OF and we
> we still enable USB_OHCI_LITTLE_ENDIAN for USB_OHCI_HCD_PCI even if
> USB_OHCI_HCD_PPC_OF_LE is not set.
I believe you are saying that we can select any valid combination
of USB_OHCI_BIG_ENDIAN_DESC, USB_OHCI_BIG_ENDIAN_MMIO, and
USB_OHCI_LITTLE_ENDIAN, without using USB_OHCI_HCD_PPC_OF_BE and
USB_OHCI_HCD_PPC_OF_LE. I agree. It looks like we can get rid of
these last two with zero loss in performance or functionality.
Do you have a patch?
-Dale
next prev parent reply other threads:[~2007-10-24 14:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-08 14:26 [PATCH] PowerPC 440EPx Sequoia USB OHCI DTS entry Valentine Barshak
2007-10-23 15:33 ` Josh Boyer
2007-10-23 15:35 ` Valentine Barshak
2007-10-23 15:50 ` Josh Boyer
2007-10-23 17:03 ` Segher Boessenkool
2007-10-23 17:18 ` Valentine Barshak
2007-10-23 21:40 ` Dale Farnsworth
2007-10-24 11:19 ` Valentine Barshak
2007-10-24 12:08 ` Dale Farnsworth
2007-10-24 13:44 ` Valentine Barshak
2007-10-24 14:10 ` Dale Farnsworth [this message]
2007-10-24 14:23 ` Valentine Barshak
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