linux-kernel - Re: [PATCH v3 07/14] software_node: Add support for fwnode

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Date:   Mon, 28 Dec 2020 18:41:01 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Daniel Scally <djrscally@...il.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        devel@...ica.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Yong Zhi <yong.zhi@...el.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Tian Shu Qiu <tian.shu.qiu@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        kieran.bingham+renesas@...asonboard.com,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Marco Felsch <m.felsch@...gutronix.de>,
        niklas.soderlund+renesas@...natech.se,
        Steve Longerbeam <slongerbeam@...il.com>,
        "Krogerus, Heikki" <heikki.krogerus@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v3 07/14] software_node: Add support for fwnode_graph*()
 family of functions

Hi Daniel,

On Thu, Dec 24, 2020 at 02:21:15PM +0000, Daniel Scally wrote:
> Hi Andy, Laurent
> 
> > On Thu, Dec 24, 2020 at 2:55 PM Laurent Pinchart
> > <laurent.pinchart@...asonboard.com> wrote:
> >> On Thu, Dec 24, 2020 at 02:24:12PM +0200, Andy Shevchenko wrote:
> >>> On Thu, Dec 24, 2020 at 3:14 AM Daniel Scally wrote:
> > 
> > ...
> > 
> >>>> +               if (!strncmp(to_swnode(port)->node->name, "port@",
> >>>
> >>> You may use here corresponding _FMT macro.
> >>>
> >>>> +                            FWNODE_GRAPH_PORT_NAME_PREFIX_LEN))
> >>>> +                       return port;
> > 
> > ...
> > 
> >>>> +       /* Ports have naming style "port@n", we need to select the n */
> >>>
> >>>> +       ret = kstrtou32(swnode->parent->node->name + FWNODE_GRAPH_PORT_NAME_PREFIX_LEN,
> >>>
> >>> Maybe a temporary variable?
> >>>
> >>>   unsigned int prefix_len = FWNODE_GRAPH_PORT_NAME_PREFIX_LEN;
> >>>   ...
> >>>   ret = kstrtou32(swnode->parent->node->name + prefix_len,
> >>
> >> Honestly I'm wondering if those macros don't hinder readability. I'd
> >> rather write
> >>
> >>         + strlen("port@")
> > 
> > Works for me, since the compiler optimizes this away to be a plain constant.
> 
> Well, how about instead of the LEN macro, we have:
> 
> #define FWNODE_GRAPH_PORT_NAME_PREFIX	"port@"
> #define FWNODE_GRAPH_PORT_NAME_FMT FWNODE_GRAPH_PORT_NAME_PREFIX "%u"
> 
> And then it's still maintainable in one place but (I think) slightly
> less clunky, since we can do strlen(FWNODE_GRAPH_PORT_NAME_PREFIX)
> 
> Or we can do strlen("port@"), I'm good either way :)

I'd be in favour of using strlen("port@") here.

At least for now. I think refactoring the use of such strings could be a
separate set at another time, if that's seen as the way to go.

-- 
Kind regards,

Sakari Ailus