From: Ralf Baechle <ralf@linux-mips.org>
To: veerasena reddy <veerasena_b@yahoo.co.in>
Cc: linux-mips <linux-mips@linux-mips.org>,
"linux-kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: linux cache routines for Write-back cache policy on MIPS24KE
Date: Wed, 3 Oct 2007 11:57:51 +0100 [thread overview]
Message-ID: <20071003105751.GD29244@linux-mips.org> (raw)
In-Reply-To: <535696.48077.qm@web8403.mail.in.yahoo.com>
On Mon, Oct 01, 2007 at 01:10:59PM +0100, veerasena reddy wrote:
> Is there any problem if we use the below API's in
> linxu-2.6.18
> - dma_cache_wback_inv()
> - dma_cache_wback()
> - dma_cache_inv()
>
> functionality wise, especially in r4k.c i dont see any
> difference between the implementation of these APIs.
>
> Can we apply the 2.6.24 patch to kill these APIs on
> 2.6.18 kernel? In this case what APIs i can use for
> writeback, invalidation or both?
>
> I couldn't find any info. related to the above API in
> DMA-API.txt. Could you please give some pointers on
> the usage/working of these APIs.
dma_cache_* were never documented. They respresent the earliest attempt
at coming up with an API that enables portable drivers and it has a few
shortcomings and like so many early things it was never formally documented,
so don't expect any well defined semantics. The functions never got
formally retired probably because it somehow managed to stay under the
radar.
Any drivers should use the APIs documented in Documentation/DMA-API.txt
only. The almost equivalent operation for dma_cache_* would be
dma_sync_single and dma_sync_sg.
Don't even dream about using dma_cache_* for anything but DMA coherency.
They're all internal low level APIs which know nothing about Linux's
virtual memory system.
Anyway, it would be much easier to help you if we knew what you are trying
to achieve with these functions.
Ralf
next prev parent reply other threads:[~2007-10-03 10:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-01 9:04 linux cache routines for Write-back cache policy on MIPS24KE veerasena reddy
2007-10-01 9:23 ` Geert Uytterhoeven
2007-10-01 10:51 ` veerasena reddy
2007-10-01 11:42 ` Geert Uytterhoeven
2007-10-01 12:13 ` veerasena reddy
2007-10-01 10:59 ` Ralf Baechle
2007-10-01 12:10 ` veerasena reddy
2007-10-03 10:57 ` Ralf Baechle [this message]
2007-10-08 13:58 ` veerasena reddy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20071003105751.GD29244@linux-mips.org \
--to=ralf@linux-mips.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@linux-mips.org \
--cc=veerasena_b@yahoo.co.in \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox