From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EC24C433B4 for ; Tue, 18 May 2021 13:31:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4196861285 for ; Tue, 18 May 2021 13:31:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349628AbhERNcY (ORCPT ); Tue, 18 May 2021 09:32:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:41320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244870AbhERNcW (ORCPT ); Tue, 18 May 2021 09:32:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1DB60611CC; Tue, 18 May 2021 13:31:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621344664; bh=X53wMEAAhoR3qDgv6I72kl2g+HLNTa0WDNa3S6R6O5c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AMaBiMyrN7AbIR6l1QmB9cO8+qQ8w15UNy5GuSflZ2m2ZOLcF05ptFN9XRkrYCY8b AihL0TPjtCDRRR5ujG+5SmJpZlHUUpVSYaHkD+IoI8anHI5a1tscqaO2hfshTPvrUQ wrm24CUkxubvt/iYKGTrXFDJjdYnqFgxjvEALRig= Date: Tue, 18 May 2021 15:31:02 +0200 From: Greg Kroah-Hartman To: Heikki Krogerus , Badhri Jagan Sridharan Cc: Guenter Roeck , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Kyle Tso Subject: Re: [PATCH v1 1/2] usb: typec: tcpm: Expose tcpm logs through a misc device Message-ID: References: <20210517233609.610248-1-badhri@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, May 18, 2021 at 04:00:48PM +0300, Heikki Krogerus wrote: > On Mon, May 17, 2021 at 04:36:08PM -0700, Badhri Jagan Sridharan wrote: > > Although TCPM logs were primarily focussed to aid developers > > during bringup, TCPM logs have proved to be critical even > > post-bringup as it provides a good starting point to triage > > interoperability issues with accessories. TCPM logs > > are exposed through debugfs filesystem. For systems that > > don't mount debugfs by default, this change introduces a > > module parameter log_misc_dev which when set exports the > > tcpm logs through a misc device. This change also leaves > > the option of exporting tcpm logs through debugfs for > > backwards compatibility. > > This does not look correct to me. At the very least you need to now > document your misc device interface. Why are you removing the choice > whether to enable this or not? The module parameter does also not > sound like a good idea at all. > > I'm really not sure about this. This is just a poor man's debugfs that > removes any choice of enabling it. Since clearly debugging related > information is what you are after here, debugfs really should be > enough for you. I agree, this is an abuse of a misc device, not ok at all. Just use debugfs if you really want this type of thing, that is what it is there for. > > > Signed-off-by: Badhri Jagan Sridharan > > --- > > drivers/usb/typec/tcpm/tcpm.c | 98 +++++++++++++++++++++++++---------- > > 1 file changed, 72 insertions(+), 26 deletions(-) > > > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > > index c4fdc00a3bc8..b79194919b27 100644 > > --- a/drivers/usb/typec/tcpm/tcpm.c > > +++ b/drivers/usb/typec/tcpm/tcpm.c > > @@ -12,6 +12,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -33,6 +34,10 @@ > > > > #include > > > > +static bool modparam_log_misc_dev; > > +module_param_named(log_misc_dev, modparam_log_misc_dev, bool, 0444); > > +MODULE_PARM_DESC(log_misc_dev, "Expose tcpm logs through misc device"); This is not the 1990's, no new module parameters please. thanks, greg k-h