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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C156CC0032E for ; Wed, 25 Oct 2023 10:50:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233435AbjJYKu6 (ORCPT ); Wed, 25 Oct 2023 06:50:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233907AbjJYKu4 (ORCPT ); Wed, 25 Oct 2023 06:50:56 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A77A7AC for ; Wed, 25 Oct 2023 03:50:50 -0700 (PDT) Received: from pendragon.ideasonboard.com (213-243-189-158.bb.dnainternet.fi [213.243.189.158]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 419CC669; Wed, 25 Oct 2023 12:50:36 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1698231036; bh=GaKOMT/bW1j8se7J5d/aUJY9NecXPg1uCLqxCZJ9J1E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ebwlOPsnNsq7OPod5mOpHoB86SZc1Or5kE0iApp32ihOUKIF3rqEsmxOmm5M7ljVn p30rxRAIe9pkexpLBRJB+ZudcrAVAQ7gzqsoozD3r80XrNbL9LbR3R3uGzb4e1woRS CJeTaShTwuF/00Hg5sf08dL1GecfYnrX9nV4Dzdo= Date: Wed, 25 Oct 2023 13:50:55 +0300 From: Laurent Pinchart To: Sakari Ailus Cc: Hans Verkuil , linux-media@vger.kernel.org, tomi.valkeinen@ideasonboard.com, jacopo.mondi@ideasonboard.com, bingbu.cao@intel.com, hongju.wang@intel.com Subject: Re: [PATCH v3 5/8] media: v4l: subdev: Make stream argument optional in state access functions Message-ID: <20231025105055.GC481@pendragon.ideasonboard.com> References: <20231023174408.803874-1-sakari.ailus@linux.intel.com> <20231023174408.803874-6-sakari.ailus@linux.intel.com> <95c4ed4d-36e5-44f7-8609-dfdb7847b0e8@xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Sakari, On Wed, Oct 25, 2023 at 10:19:15AM +0000, Sakari Ailus wrote: > On Wed, Oct 25, 2023 at 11:53:35AM +0200, Hans Verkuil wrote: > > On 23/10/2023 19:44, Sakari Ailus wrote: > > > The sub-device state access functions take three arguments: sub-device > > > state, pad and stream. The stream is not relevant for the majority of > > > drivers and having to specify 0 for the stream is considered a nuisance. > > > > > > Provide a two-argument macros for these state access functions to cover > > > the needs of stream-unaware users. > > > > > > Signed-off-by: Sakari Ailus > > > --- > > > drivers/media/v4l2-core/v4l2-subdev.c | 18 ++++++------- > > > include/media/v4l2-subdev.h | 39 ++++++++++++++++++++------- > > > 2 files changed, 39 insertions(+), 18 deletions(-) > > > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > > index f0f0af48730f..e35226587244 100644 > > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > > @@ -1671,8 +1671,8 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd, > > > EXPORT_SYMBOL_GPL(v4l2_subdev_set_routing_with_fmt); > > > > > > struct v4l2_mbus_framefmt * > > > -v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad, > > > - u32 stream) > > > +__v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, > > > + unsigned int pad, u32 stream) > > > { > > > struct v4l2_subdev_stream_configs *stream_configs; > > > unsigned int i; > > > @@ -1702,11 +1702,11 @@ v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad, > > > > > > return NULL; > > > } > > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_format); > > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_format); > > > > > > struct v4l2_rect * > > > -v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad, > > > - u32 stream) > > > +__v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad, > > > + u32 stream) > > > { > > > struct v4l2_subdev_stream_configs *stream_configs; > > > unsigned int i; > > > @@ -1736,11 +1736,11 @@ v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad, > > > > > > return NULL; > > > } > > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_crop); > > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_crop); > > > > > > struct v4l2_rect * > > > -v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, unsigned int pad, > > > - u32 stream) > > > +__v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, > > > + unsigned int pad, u32 stream) > > > { > > > struct v4l2_subdev_stream_configs *stream_configs; > > > unsigned int i; > > > @@ -1770,7 +1770,7 @@ v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, unsigned int pad, > > > > > > return NULL; > > > } > > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_compose); > > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_compose); > > > > > > int v4l2_subdev_routing_find_opposite_end(const struct v4l2_subdev_krouting *routing, > > > u32 pad, u32 stream, u32 *other_pad, > > > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h > > > index 71cb35133b4a..12eb0fe746d7 100644 > > > --- a/include/media/v4l2-subdev.h > > > +++ b/include/media/v4l2-subdev.h > > > @@ -1545,7 +1545,7 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd, > > > * v4l2_subdev_state_get_format() - Get pointer to a stream format > > > * @state: subdevice state > > > * @pad: pad id > > > - * @stream: stream id > > > + * @...: stream id (optional argument) > > > * > > > * This returns a pointer to &struct v4l2_mbus_framefmt for the given pad + > > > * stream in the subdev state. > > > @@ -1553,15 +1553,22 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd, > > > * For stream-unaware drivers the format for the corresponding pad is returned. > > > * If the pad does not exist, NULL is returned. > > > */ > > > +#define v4l2_subdev_state_get_format(state, pad, ...) \ > > > + __v4l2_subdev_state_get_format_ ## __VA_OPT__(stream) \ > > > + (state, pad __VA_OPT__(,) __VA_ARGS__) > > > +#define __v4l2_subdev_state_get_format_(state, pad) \ > > > + __v4l2_subdev_state_get_format(state, pad, 0) > > > +#define __v4l2_subdev_state_get_format_stream(state, pad, stream) \ > > > + __v4l2_subdev_state_get_format(state, pad, stream) > > > > Hmm, 'git grep __VA_OPT__' finds no use of this in the kernel. Are you sure this > > is safe to use? Does clang support it? Do all gcc versions that the kernel support > > implement it? > > > > A 10+ for creativity, but I'm a bit concerned about it. > > :-) > > I noticed the problem, too, as the lkp bot failed compiling this on GCC > 7.5. Indeed only GCC 8 supports __VA_OPT__ but the oldest GCC version > supported for kernel compilation is 7.1. So __VA_OPT__ isn't... an option. > > I thought this could be done using variable arguments, making most error > handling take place at runtime (for GCC versions not supporting > __VA_OPT__), but then Laurent figured this can be done with just > __VA_ARGS__ which is part of C99. > > The code would look like this, which is only slightly less understandable > than with __VA_OPT__: > > #define v4l2_subdev_state_get_format(...) \ > __v4l2_subdev_state_get_format_var(__VA_ARGS__, , _2)(__VA_ARGS__) How about __v4l2_subdev_state_get_format_var(__VA_ARGS__, _stream, _pad)(__VA_ARGS__) ? The internal macro and function names would then be more explicit. > #define __v4l2_subdev_state_get_format_var(_1, _2, _3, NUM, ...) \ > __v4l2_subdev_state_get_format ## NUM > #define __v4l2_subdev_state_get_format_2(state, pad) \ > __v4l2_subdev_state_get_format(state, pad, 0) > struct v4l2_mbus_framefmt * > __v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, > unsigned int pad, u32 stream); > > > And if there are only a few drivers that need to give a specific stream, > > wouldn't it be easier to just have a v4l2_subdev_state_get_format_stream > > function and a static inline v4l2_subdev_state_get_format() that just calls > > the _stream version with 0? > > I'm trying to shorten function names here: they're overly long. Also I'd > like to see a single set of API functions to access sub-device state > information irrespective of how it is stored. I originally proposed just > specifying stream zero but both Laurent and Tomi opined against it. -- Regards, Laurent Pinchart