From: "John W. Linville" <linville@tuxdriver.com>
To: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>,
netdev@vger.kernel.org, linux-wireless@vger.kernel.org
Subject: Re: [PATCH] ethtool: fix ethtool_get_regs() to work with zero length registers
Date: Wed, 20 Jul 2011 10:36:12 -0400 [thread overview]
Message-ID: <20110720143611.GA18231@tuxdriver.com> (raw)
In-Reply-To: <4E26C2DC.8090208@qca.qualcomm.com>
On Wed, Jul 20, 2011 at 02:58:20PM +0300, Kalle Valo wrote:
> On 07/20/2011 02:38 PM, Ben Hutchings wrote:
> > On Wed, 2011-07-20 at 12:18 +0300, Kalle Valo wrote:
> >> cfg80211 exports zero length register size as it currently only uses
> >> struct ethtool_regs.version to export struct wiphy.hw_version.
> > [...]
> >
> > The ethtool_regs::version field represents the version of the register
> > dump format. This may or may not relate to a hardware version.
This seems like a strange claim to make...?
struct ethtool_regs {
__u32 cmd;
__u32 version; /* driver-specific, indicates different chips/revs */
__u32 len; /* bytes */
__u8 data[0];
};
That "indicates different chips/revs" comment has been there at least
as long as the kernel has been in git (back to the 2.6.12 era).
> > If you don't actually provide a register dump then don't implement this
> > operation.
>
> Then we have a problem as cfg80211 exports the hw version without any
> register dumps:
>
> static int cfg80211_get_regs_len(struct net_device *dev)
> {
> /* For now, return 0... */
> return 0;
> }
>
> static void cfg80211_get_regs(struct net_device *dev, struct
> ethtool_regs *regs,
> void *data)
> {
> struct wireless_dev *wdev = dev->ieee80211_ptr;
>
> regs->version = wdev->wiphy->hw_version;
> regs->len = 0;
> }
>
> And this has been there a long time already. How cfg80211 should export
> hw version if this is not a proper way?
The ethool binary already has support for the at76c50x_usb driver,
which uses this very mechanism in exactly this way. I know this
worked previously, although I don't know what might have changed to
break it...?
John
--
John W. Linville Someday the world will need a hero, and you
linville@tuxdriver.com might be all we have. Be ready.
next prev parent reply other threads:[~2011-07-20 14:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 9:18 [PATCH] ethtool: fix ethtool_get_regs() to work with zero length registers Kalle Valo
2011-07-20 11:38 ` Ben Hutchings
2011-07-20 11:58 ` Kalle Valo
2011-07-20 14:36 ` John W. Linville [this message]
2011-07-21 17:46 ` Ben Hutchings
2011-07-21 17:54 ` [PATCH net-2.6] ethtool: Allow zero-length register dumps again Ben Hutchings
2011-07-21 22:25 ` David Miller
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=20110720143611.GA18231@tuxdriver.com \
--to=linville@tuxdriver.com \
--cc=bhutchings@solarflare.com \
--cc=kvalo@qca.qualcomm.com \
--cc=linux-wireless@vger.kernel.org \
--cc=netdev@vger.kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).