From: Oliver Neukum <oliver@neukum.org>
To: "Francis Moreau" <francis.moro@gmail.com>
Cc: "David Brownell" <david-b@pacbell.net>,
linux-usb@vger.kernel.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: usb_get_status(): what a weird implementation !
Date: Mon, 30 Jun 2008 16:11:41 +0200 [thread overview]
Message-ID: <200806301611.42464.oliver@neukum.org> (raw)
In-Reply-To: <38b2ab8a0806300703j7c0f0567w4cf1730fbe375c00@mail.gmail.com>
Am Montag 30 Juni 2008 16:03:52 schrieb Francis Moreau:
> On Mon, Jun 30, 2008 at 3:51 PM, Oliver Neukum <oliver@neukum.org> wrote:
> >
> > If your buffer is smaller than CACHE_LINE_SIZE it should work.
> > However, this needs input from people who understand DMA in and out.
>
> yeah, that's the reason why it's a hack.
>
> Maybe adding a new helper in the dma API would be better...
>
> > But how large is 2 * CACHE_LINE_SIZE compared to the kernel stack?
>
> CACHE_LINE_SIZE = 32 bytes is common for embedded systems I guess.
> For big system, I dunno.
>
> Kernel stack size is usually 4KiB.
>
Well, we have:
asm-mips/mach-ip32/kmalloc.h:#define ARCH_KMALLOC_MINALIGN 128
That's 256 bytes, that is 1/16 of the stack.
Regards
Oliver
next prev parent reply other threads:[~2008-06-30 14:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200806261011.00287.oliver@neukum.org>
[not found] ` <200806301346.11267.oliver@neukum.org>
[not found] ` <38b2ab8a0806300541q756e9b6fl445a5ee69d403ce7@mail.gmail.com>
2008-06-30 13:51 ` Oliver Neukum
2008-06-30 14:03 ` Francis Moreau
2008-06-30 14:11 ` Oliver Neukum [this message]
2008-06-30 14:22 ` Francis Moreau
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