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Date:   Wed, 17 Feb 2021 12:52:57 -0800
From:   "Life is hard, and then you die" <ronald@innovation.ch>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Sergiu Cuciurean <sergiu.cuciurean@analog.com>,
        Lee Jones <lee.jones@linaro.org>, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] Input: applespi: Add trace_event module param for
 early tracing.
Message-ID: <20210217205257.GB25685@innovation.ch>
References: <20210217190718.11035-1-ronald@innovation.ch>
 <20210217190718.11035-3-ronald@innovation.ch>
 <YC176rlGQeyKuOpn@google.com>
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  Hi Dmitry,

On Wed, Feb 17, 2021 at 12:26:18PM -0800, Dmitry Torokhov wrote:
> 
> On Wed, Feb 17, 2021 at 11:07:18AM -0800, Ronald Tschal?r wrote:
> > The problem is that tracing can't be set via sysfs until the module is
> > loaded, at which point the keyboard and trackpad initialization commands
> > have already been run and hence tracing can't be used to debug problems
> > here.
> > 
> > Adding this param allows tracing to be enabled for messages sent and
> > received during module probing. It takes comma-separated list of events,
> > e.g.
> > 
> >   trace_event=applespi_tp_ini_cmd,applespi_bad_crc
> 
> You can unbind and rebind a device to a driver via sysfs as many times
> as needed (see bind and unbind driver sysfs attributes), so I believe

Hmm, I'm going to have to play with that a bit, but one place it still
won't help I think is something we ran into in practise: init was
failing during boot, but was successfull later on.


  Cheers,

  Ronald