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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 E5CD3C433DF for ; Wed, 24 Jun 2020 00:13:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C46EF20C09 for ; Wed, 24 Jun 2020 00:13:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="icZ6D4SB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387922AbgFXANW (ORCPT ); Tue, 23 Jun 2020 20:13:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387693AbgFXANW (ORCPT ); Tue, 23 Jun 2020 20:13:22 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3F1AC061573; Tue, 23 Jun 2020 17:13:21 -0700 (PDT) Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 1CF2D2A9; Wed, 24 Jun 2020 02:13:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1592957599; bh=M68BYCDz1JVEV2EjFuHU6tktuW92HXc9WgbmwmcQSXM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=icZ6D4SBGPXi20NW53ENnACxgYy7LxNuFLyMxoOlv4aNDUjuObLcwQ4/EpXy17f/a mYn9gTe0NnFbGm/sMemHFAAw8qTLvvSUupt9cX9O698TMmTTvIWDXGaJAXUM18s4Fm pcqUI7ehXrBvamTUm5iCpGMSOffOXtwGXVGkTQy8= Date: Wed, 24 Jun 2020 03:12:53 +0300 From: Laurent Pinchart To: Sakari Ailus Cc: Laurent Pinchart , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Jacopo Mondi , Niklas =?utf-8?Q?S=C3=B6derlund?= , Kieran Bingham , Lad Prabhakar Subject: Re: [PATCH v3 1/3] media: v4l2-async: Accept endpoints and devices for fwnode matching Message-ID: <20200624001253.GS5870@pendragon.ideasonboard.com> References: <20200621000028.4591-1-laurent.pinchart+renesas@ideasonboard.com> <20200621000028.4591-2-laurent.pinchart+renesas@ideasonboard.com> <20200623211306.GF870@valkosipuli.retiisi.org.uk> <20200623212241.GD5870@pendragon.ideasonboard.com> <20200623231205.GG870@valkosipuli.retiisi.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200623231205.GG870@valkosipuli.retiisi.org.uk> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Sakari, On Wed, Jun 24, 2020 at 02:12:05AM +0300, Sakari Ailus wrote: > On Wed, Jun 24, 2020 at 12:22:41AM +0300, Laurent Pinchart wrote: > > On Wed, Jun 24, 2020 at 12:13:06AM +0300, Sakari Ailus wrote: > >> On Sun, Jun 21, 2020 at 03:00:26AM +0300, Laurent Pinchart wrote: > >>> fwnode matching was designed to match on nodes corresponding to a > >>> device. Some drivers, however, needed to match on endpoints, and have > >>> passed endpoint fwnodes to v4l2-async. This works when both the subdev > >>> and the notifier use the same fwnode types (endpoint or device), but > >>> makes drivers that use different types incompatible. > >>> > >>> Fix this by extending the fwnode match to handle fwnodes of different > >>> types. When the types (deduced from the presence of remote endpoints) > >>> are different, retrieve the device fwnode for the side that provides an > >>> endpoint fwnode, and compare it with the device fwnode provided by the > >>> other side. This allows interoperability between all drivers, regardless > >>> of which type of fwnode they use for matching. > >>> > >>> Signed-off-by: Laurent Pinchart > >>> Tested-by: Lad Prabhakar > >>> Reviewed-by: Kieran Bingham > >>> Reviewed-by: Jacopo Mondi > >>> --- > >>> Changes since v2: > >>> > >>> - Add comment to explain that we're matching connecting endpoints > >>> - Don't check fwnode name to detect endpoint > >>> --- > >>> drivers/media/v4l2-core/v4l2-async.c | 45 +++++++++++++++++++++++++++- > >>> 1 file changed, 44 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c > >>> index 8bde33c21ce4..f82e0a32647d 100644 > >>> --- a/drivers/media/v4l2-core/v4l2-async.c > >>> +++ b/drivers/media/v4l2-core/v4l2-async.c > >>> @@ -71,7 +71,50 @@ static bool match_devname(struct v4l2_subdev *sd, > >>> > >>> static bool match_fwnode(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd) > >>> { > >>> - return sd->fwnode == asd->match.fwnode; > >>> + struct fwnode_handle *other_fwnode; > >>> + struct fwnode_handle *dev_fwnode; > >>> + bool asd_fwnode_is_ep; > >>> + bool sd_fwnode_is_ep; > >>> + > >>> + /* > >>> + * Both the subdev and the async subdev can provide either an endpoint > >>> + * fwnode or a device fwnode. Start with the simple case of direct > >>> + * fwnode matching. > >>> + */ > >>> + if (sd->fwnode == asd->match.fwnode) > >>> + return true; > >>> + > >>> + /* > >>> + * Otherwise, check if the sd fwnode and the asd fwnode refer to an > >>> + * endpoint or a device. If they're of the same type, there's no match. > >>> + * Technically speaking this checks if the nodes refer to a connected > >>> + * endpoint, which is the simplest check that works for both OF and > >>> + * ACPI. This won't make a difference, as drivers should not try to > >>> + * match unconnected endpoints. > >>> + */ > >>> + sd_fwnode_is_ep = fwnode_property_present(sd->fwnode, > >>> + "remote-endpoint"); > >>> + asd_fwnode_is_ep = fwnode_property_present(asd->match.fwnode, > >>> + "remote-endpoint"); > >> > >> Please don't try parsing graph bindings outside the main parsers. > > > > Why is that ? On the DT side, bindings are considered to be stable, so > > isolating their parsing in helpers would not help with ABI compatibility > > anyway. Maybe it would be useful if you could explain how graph parsing > > works in ACPI ? The fact that there's a remote-endpoint property without > > endpoints is a the minimum quite puzzling. > > No other drivers (or frameworks to my knowledge) work with the graphs > directly anymore. There was a staging driver (IMX) that did but that has > been fixed now. It's easier to ensure the code is correct --- this is > because the data structure is hard to parse, especially while taking > firmware type differences into account but the functions that access it are > relatively simple to use. > > The fwnode property API has operations callbacks that are specific to the > type of the node. Most access functions have a firmware specific backend. > > With the presence of the "remote-endpoint" property there's no variation > across the firmware types, at least not right now. But still putting it > here right now looks like technical debt to me: much of the code parsing > graph data structure outside the main parser has been buggy in the past. For my information, could you still briefly explain how remote-endpoint works on ACPI, without any fwnode named "endpoint" ? > >> There's no API function to do just this, but you could go and check for the > >> port parent right away. The code might be even more simple that way. > > > > How will that help ? With OF at least, fwnode_graph_get_port_parent() > > will return the grand-parent if the passed node isn't an endpoint, not > > much can be deduced from that. > > I meant to say fwnode_graph_get_remote_endpoint(). You'd need to release > the fwnode reference, too. That makes more sense :-) > >> Alternatively, I guess we could add fwnode_graph_is_endpoint() or something > >> but I wonder if it'd be worth it just for this. Would static inline bool fwnode_graph_is_endpoint(struct fwnode_handle *fwnode) { return fwnode_property_present(fwnode, "remote-endpoint"); } in include/linux/property.h be acceptable to you ? > >>> + > >>> + if (sd_fwnode_is_ep == asd_fwnode_is_ep) > >>> + return false; > >>> + > >>> + /* > >>> + * The sd and asd fwnodes are of different types. Get the device fwnode > >>> + * parent of the endpoint fwnode, and compare it with the other fwnode. > >>> + */ > >>> + if (sd_fwnode_is_ep) { > >>> + dev_fwnode = fwnode_graph_get_port_parent(sd->fwnode); > >>> + other_fwnode = asd->match.fwnode; > >>> + } else { > >>> + dev_fwnode = fwnode_graph_get_port_parent(asd->match.fwnode); > >>> + other_fwnode = sd->fwnode; > >>> + } > >>> + > >>> + fwnode_handle_put(dev_fwnode); > >>> + > >>> + return dev_fwnode == other_fwnode; > >>> } > >>> > >>> static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd) -- Regards, Laurent Pinchart