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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B6F3EECE58E for ; Wed, 2 Oct 2019 16:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97D07222C3 for ; Wed, 2 Oct 2019 16:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729098AbfJBQG4 (ORCPT ); Wed, 2 Oct 2019 12:06:56 -0400 Received: from mga17.intel.com ([192.55.52.151]:54468 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725799AbfJBQGz (ORCPT ); Wed, 2 Oct 2019 12:06:55 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Oct 2019 09:06:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,249,1566889200"; d="scan'208";a="205369808" Received: from kuha.fi.intel.com ([10.237.72.53]) by fmsmga001.fm.intel.com with SMTP; 02 Oct 2019 09:06:53 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Wed, 02 Oct 2019 19:06:52 +0300 Date: Wed, 2 Oct 2019 19:06:52 +0300 From: Heikki Krogerus To: Guenter Roeck Cc: Hans de Goede , linux-usb@vger.kernel.org Subject: Re: [PATCH 1/7] usb: typec: Copy everything from struct typec_capability during registration Message-ID: <20191002160652.GB19836@kuha.fi.intel.com> References: <20191001094858.68643-1-heikki.krogerus@linux.intel.com> <20191001094858.68643-2-heikki.krogerus@linux.intel.com> <9173aabc-3e61-fc9b-e01e-0f1ce78429a2@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9173aabc-3e61-fc9b-e01e-0f1ce78429a2@roeck-us.net> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Oct 01, 2019 at 06:08:17AM -0700, Guenter Roeck wrote: > On 10/1/19 2:48 AM, Heikki Krogerus wrote: > > Copying everything from struct typec_capability to struct > > typec_port during port registration. > > > What is the purpose of this patch ? To reduce the number of indirections at > runtime, or to avoid having to have cap around ? To get rid of the cap member. > FWIW, it looks like the code doesn't copy _all_ variables (eg cap->try_role), > and it doesn't drop port->cap. Am I missing something ? We can't drop port->cap at this point because the drivers still depend on it. This patch is the "prepare" phase of the series. The last patch in the series finally drops the member. I'll improve the commit message. > > Signed-off-by: Heikki Krogerus > > --- > > drivers/usb/typec/class.c | 55 +++++++++++++++++++++++++-------------- > > 1 file changed, 35 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c > > index 94a3eda62add..3835e2d9fba6 100644 > > --- a/drivers/usb/typec/class.c > > +++ b/drivers/usb/typec/class.c > > @@ -46,8 +46,14 @@ struct typec_port { > > enum typec_role vconn_role; > > enum typec_pwr_opmode pwr_opmode; > > enum typec_port_type port_type; > > + enum typec_port_type fixed_role; > > + enum typec_port_data port_roles; > > + enum typec_accessory accessory[TYPEC_MAX_ACCESSORY]; > > Would a pointer to cap->accessory be sufficient ? Or is there a reason to copy > the actual array ? No. The point is to get rid of the cap member. > > struct mutex port_type_lock; > > + u16 revision; > > + u16 pd_revision; > > + > > enum typec_orientation orientation; > > struct typec_switch *sw; > > struct typec_mux *mux; > > @@ -950,7 +956,7 @@ preferred_role_store(struct device *dev, struct device_attribute *attr, > > int role; > > int ret; > > - if (port->cap->type != TYPEC_PORT_DRP) { > > + if (port->fixed_role != TYPEC_PORT_DRP) { > > dev_dbg(dev, "Preferred role only supported with DRP ports\n"); > > return -EOPNOTSUPP; > > } > > @@ -982,7 +988,7 @@ preferred_role_show(struct device *dev, struct device_attribute *attr, > > { > > struct typec_port *port = to_typec_port(dev); > > - if (port->cap->type != TYPEC_PORT_DRP) > > + if (port->fixed_role != TYPEC_PORT_DRP) > > return 0; > > if (port->prefer_role < 0) > > @@ -1009,7 +1015,7 @@ static ssize_t data_role_store(struct device *dev, > > return ret; > > mutex_lock(&port->port_type_lock); > > - if (port->cap->data != TYPEC_PORT_DRD) { > > + if (port->port_roles != TYPEC_PORT_DRD) { > > ret = -EOPNOTSUPP; > > goto unlock_and_ret; > > } > > @@ -1029,7 +1035,7 @@ static ssize_t data_role_show(struct device *dev, > > { > > struct typec_port *port = to_typec_port(dev); > > - if (port->cap->data == TYPEC_PORT_DRD) > > + if (port->port_roles == TYPEC_PORT_DRD) > > return sprintf(buf, "%s\n", port->data_role == TYPEC_HOST ? > > "[host] device" : "host [device]"); > > @@ -1044,7 +1050,7 @@ static ssize_t power_role_store(struct device *dev, > > struct typec_port *port = to_typec_port(dev); > > int ret; > > - if (!port->cap->pd_revision) { > > + if (!port->pd_revision) { > > dev_dbg(dev, "USB Power Delivery not supported\n"); > > return -EOPNOTSUPP; > > } > > @@ -1064,9 +1070,9 @@ static ssize_t power_role_store(struct device *dev, > > return ret; > > mutex_lock(&port->port_type_lock); > > - if (port->port_type != TYPEC_PORT_DRP) { > > + if (port->fixed_role != TYPEC_PORT_DRP) { > > This is a semantic change: Previously, it compared the _current_ port type. > Now it compares the initial (fixed) port type. Is this on purpose ? > > [ comment written before I noticed the change below. See there. ] > > > dev_dbg(dev, "port type fixed at \"%s\"", > > - typec_port_power_roles[port->port_type]); > > + typec_port_power_roles[port->fixed_role]); > > ret = -EOPNOTSUPP; > > goto unlock_and_ret; > > } > > @@ -1086,7 +1092,7 @@ static ssize_t power_role_show(struct device *dev, > > { > > struct typec_port *port = to_typec_port(dev); > > - if (port->cap->type == TYPEC_PORT_DRP) > > + if (port->fixed_role == TYPEC_PORT_DRP) > > return sprintf(buf, "%s\n", port->pwr_role == TYPEC_SOURCE ? > > "[source] sink" : "source [sink]"); > > @@ -1102,7 +1108,7 @@ port_type_store(struct device *dev, struct device_attribute *attr, > > int ret; > > enum typec_port_type type; > > - if (!port->cap->port_type_set || port->cap->type != TYPEC_PORT_DRP) { > > + if (!port->cap->port_type_set || port->fixed_role != TYPEC_PORT_DRP) { > > dev_dbg(dev, "changing port type not supported\n"); > > return -EOPNOTSUPP; > > } > > @@ -1114,7 +1120,7 @@ port_type_store(struct device *dev, struct device_attribute *attr, > > type = ret; > > mutex_lock(&port->port_type_lock); > > - if (port->port_type == type) { > > + if (port->fixed_role == type) { > > This seems wrong. > > > ret = size; > > goto unlock_and_ret; > > } > > @@ -1123,7 +1129,7 @@ port_type_store(struct device *dev, struct device_attribute *attr, > > if (ret) > > goto unlock_and_ret; > > - port->port_type = type; > > + port->fixed_role = type; > > As does this. It changes the semantics of all checks that used to be against > port->cap->type, except for the one I commented on above. If that is intentional, > the variable name "fixed_role" seems inappropriate. > > Overall, I would have thought that "fixed_role" could essentially be a boolean, > set to true if cap->type is not TYPEC_PORT_DRP. That would make the code easier > to understand. Right now I am just confused about the use of port_type vs. > fixed_role. Because the idea is to get rid of the cap member, I have to store the actual capability of the port in one member, and the one supplied by the user in another new member. I chose to use the "port_type" member to hold the actual capability of the port, and introduced the "fixed_type" to hold the one given by the user. I'm happy to improve this, but I'm not sure what are you proposing here? Note. We can not use boolean variable here, because the user may also decide to set the value to "dual". This is a bit off topic, but that attribute file is really horrible. Right now there is no way to know the actual capability of the port in user space. If something changes a DRP port into sink or source, there is no way to know after that that the port is actually DRP capable. So that ABI is "buggy", but even without the problem, I still really think that allowing the capabilities to be changed like that in general is completely wrong. I don't have a problem with changing the capabilities, but IMO it should be handled at one level higher, at the controller device level. If the capabilities of a port need to be changed, the old port should be removed, and a new with the new capabilities registered. That is the only way to handle it without making things unnecessarily difficult for the user space. I'm pretty sure that that was my counter proposal already at the time when the attribute file was introduced, but I don't remember why wasn't it accepted at the time? My protest against adding that attribute file was in any case ignored :-(. In any case, my plan was to later propose a new sysfs group that we offer to the parent controller devices instead assigning it to the port devices, and that group is meant to allow port capability changes the way I explained above. Unless of course you are against it? thanks, -- heikki