netdev - Re: [PATCH 04/24] rtw89: add debug files

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Date:   Mon, 5 Jul 2021 11:09:33 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Pkshih <pkshih@...ltek.com>
Cc:     Brian Norris <briannorris@...omium.org>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Kalle Valo <kvalo@...eaurora.org>
Subject: Re: [PATCH 04/24] rtw89: add debug files

On Mon, Jul 05, 2021 at 08:58:51AM +0000, Pkshih wrote:
> 
> > -----Original Message-----
> > From: Brian Norris [mailto:briannorris@...omium.org]
> > Sent: Saturday, July 03, 2021 2:38 AM
> > To: Oleksij Rempel
> > Cc: Pkshih; Kalle Valo; linux-wireless; <netdev@...r.kernel.org>; Sascha Hauer
> > Subject: Re: [PATCH 04/24] rtw89: add debug files
> > 
> > On Fri, Jul 2, 2021 at 10:57 AM Oleksij Rempel <o.rempel@...gutronix.de> wrote:
> > > On Fri, Jul 02, 2021 at 10:08:53AM -0700, Brian Norris wrote:
> > > > On Fri, Jul 2, 2021 at 12:23 AM Oleksij Rempel <o.rempel@...gutronix.de> wrote:
> > > > > For dynamic debugging we usually use ethtool msglvl.
> > > > > Please, convert all dev_err/warn/inf.... to netif_ counterparts
> > > >
> > > > Have you ever looked at a WiFi driver?
> > >
> > > Yes. You can parse the kernel log for my commits.
> > 
> > OK! So I see you've touched a lot of ath9k, >3 years ago. You might
> > notice that it is one such example -- it supports exactly the same
> > kind of debugfs file, with a set of ath_dbg() log types. Why doesn't
> > it use this netif debug logging?
> > 
> > > > I haven't seen a single one that uses netif_*() for logging.
> > > > On the other hand, almost every
> > > > single one has a similar module parameter or debugfs knob for enabling
> > > > different types of debug messages.
> > > >
> > > > As it stands, the NETIF_* categories don't really align at all with
> > > > the kinds of message categories most WiFi drivers support. Do you
> > > > propose adding a bunch of new options to the netif debug feature?
> > >
> > > Why not? It make no sense or it is just "it is tradition, we never do
> > > it!" ?
> > 
> > Well mainly, I don't really like people dreaming up arbitrary rules
> > and enforcing them only on new submissions. If such a change was
> > Recommended, it seems like a better first step would be to prove that
> > existing drivers (where there are numerous examples) can be converted
> > nicely, instead of pushing the work to new contributors arbitrarily.
> > Otherwise, the bar for new contributions gets exceedingly high -- this
> > one has already sat for more than 6 months with depressingly little
> > useful feedback.
> > 
> > I also know very little about this netif log level feature, but if it
> > really depends on ethtool (seems like it does?) -- I don't even bother
> > installing ethtool on most of my systems. It's much easier to poke at
> > debugfs, sysfs, etc., than to construct the relevant ethtool ioctl()s
> > or netlink messages. It also seems that these debug knobs can't be set
> > before the driver finishes coming up, so one would still need a module
> > parameter to mirror some of the same features. Additionally, a WiFi
> > driver doesn't even have a netdev to speak of until after a lot of the
> > interesting stuff comes up (much of the mac80211 framework focuses on
> > a |struct ieee80211_hw| and a |struct wiphy|), so I'm not sure your
> > suggestion really fits these sorts of drivers (and the things they
> > might like to support debug-logging for) at all.
> > 
> > Anyway, if Ping-Ke wants to paint this bikeshed for you, I won't stop him.
> 
> I encounter the problems you mentioned mostly:
> 1. no netdev to be the parameter 'dev' of 'netif_dbg(priv, type, dev, format, args...)'
> 2. predefined 'type' isn't enough for wifi application. There're many wifi- or vendor-
>    specific components, such as RF calibration, BT coexistence, DIG, CFO and so on.
> 
> So, I don't plan to change them for now.

OK, understand.

Regards,
Oleksij
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