All of lore.kernel.org
 help / color / mirror / Atom feed
From: hayashi.kunihiko@socionext.com (Kunihiko Hayashi)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: mm: define NET_IP_ALIGN to 0
Date: Thu, 29 Nov 2018 10:51:39 +0900	[thread overview]
Message-ID: <20181129105139.F7FE.4A936039@socionext.com> (raw)
In-Reply-To: <20181128120455.GB24868@arm.com>

Hi Will,

On Wed, 28 Nov 2018 12:04:56 +0000 <will.deacon@arm.com> wrote:

> Hi Kunihiko,
> 
> On Wed, Nov 28, 2018 at 03:02:25PM +0900, Kunihiko Hayashi wrote:
> > I found that arm64 board that had AVE controller couldn't receive
> > any packets after this change.
> > 
> > AVE controller (hardware) forces to ignore lower 2bits of buffer start address,
> > that is, the address is always aligned with 4bytes.
> > And more, the controller puts received datas with "2byte headroom" [1].
> > 
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/ethernet/socionext/sni_ave.c#n591
> 
> Is this "2-byte headroom" a fixed property of the hardware? If so, it seems
> like you should just be using 2 instead of NET_IP_ALIGN when calculating the
> DMA address of the skb buffer.

Yes, 2-byte headroom is a hardware specific property.
I've already calculated the DMA address with NET_IP_ALIGN, so I'll replace it
with my own macro as a hardware specific value.

Thank you,

---
Best Regards,
Kunihiko Hayashi

      reply	other threads:[~2018-11-29  1:51 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-07 17:10 [PATCH] arm64: mm: define NET_IP_ALIGN to 0 Ard Biesheuvel
2018-11-07 18:10 ` Mark Rutland
2018-11-07 23:18   ` Ard Biesheuvel
2018-11-08 10:06     ` Mark Rutland
2018-11-08 10:34       ` Ard Biesheuvel
2018-11-07 21:14 ` Will Deacon
2018-11-08 12:22 ` Ilias Apalodimas
2018-11-08 17:51 ` Catalin Marinas
2018-11-28  6:02 ` Kunihiko Hayashi
2018-11-28 11:58   ` Ard Biesheuvel
2018-11-29  1:50     ` Kunihiko Hayashi
2018-11-28 12:04   ` Will Deacon
2018-11-29  1:51     ` Kunihiko Hayashi [this message]

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=20181129105139.F7FE.4A936039@socionext.com \
    --to=hayashi.kunihiko@socionext.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.