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 79101C3DA79 for ; Fri, 23 Dec 2022 13:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235843AbiLWNl7 (ORCPT ); Fri, 23 Dec 2022 08:41:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230247AbiLWNlz (ORCPT ); Fri, 23 Dec 2022 08:41:55 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 285F1186F9; Fri, 23 Dec 2022 05:41:54 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D313CB82033; Fri, 23 Dec 2022 13:41:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F6A3C433D2; Fri, 23 Dec 2022 13:41:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671802911; bh=iy9TCYFDK/6ge2wxUO12WDZJ23hlv+fXg+Yxp1If4xw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=I8eiHvbbBm5AyKg3zm0Y/3zLb/1xtgnIxiv8omT3hfi8DcB1Se8NYNXQibX8yhntK SZVQ9UOYPa4NXE5BGPXpTQjosmRTXitCjxlITgBAlbuxKQtuS4/iGpdvTASQCypNht +wGVD/OtzDpQJqP9xvHJn/gGHdW+8C1fpoJu0SRCrV07g47ze5+DtW0bWnC844K2xM eqIdZU//S9pYqW7P3L+W7pMfgOfcFWHHCcu4cvQUoQq4a/djyMCRC+8bpz15UWiv/V +iTx9X/TdnlU2luT72ox8AqMBCxkETWT96uPriXrR4zIAzNHFG7T3XvD7jQQ13bHNG kRj3aKktHAJ1A== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1p8iJs-0008Q9-1R; Fri, 23 Dec 2022 14:42:40 +0100 Date: Fri, 23 Dec 2022 14:42:40 +0100 From: Johan Hovold To: Matthias Kaehlcke Cc: Rob Herring , Greg Kroah-Hartman , Douglas Anderson , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Stefan Wahren , Ravi Chandra Sadineni Subject: Re: [PATCH] usb: misc: onboard_usb_hub: Don't defer probing for 'incomplete' DT nodes Message-ID: References: <20221220004427.1.If5e7ec83b1782e4dffa6ea759416a27326c8231d@changeid> 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-kernel@vger.kernel.org On Tue, Dec 20, 2022 at 02:15:19PM +0000, Matthias Kaehlcke wrote: > Hi Johan, > > On Tue, Dec 20, 2022 at 08:55:52AM +0100, Johan Hovold wrote: > > On Tue, Dec 20, 2022 at 12:45:01AM +0000, Matthias Kaehlcke wrote: > > > Some boards have device tree nodes for USB hubs supported by the > > > onboard_usb_hub driver, but the nodes don't have all properties > > > needed for the driver to work properly (which is not necessarily > > > an error in the DT). Currently _find_onboard_hub() returns > > > -EPROBE_DEFER in such cases, which results in an unusable USB hub, > > > since successive probes fail in the same way. Use the absence of > > > the "vdd" supply as an indicator of such 'incomplete' DT nodes > > > and return -ENODEV. > > > > > > Fixes: 8bc063641ceb ("usb: misc: Add onboard_usb_hub driver") > > > Reported-by: Stefan Wahren > > > Signed-off-by: Matthias Kaehlcke > > > --- > > > > > > drivers/usb/misc/onboard_usb_hub.c | 9 +++++++++ > > > 1 file changed, 9 insertions(+) > > > > > > diff --git a/drivers/usb/misc/onboard_usb_hub.c b/drivers/usb/misc/onboard_usb_hub.c > > > index d63c63942af1..2968da515016 100644 > > > --- a/drivers/usb/misc/onboard_usb_hub.c > > > +++ b/drivers/usb/misc/onboard_usb_hub.c > > > @@ -363,6 +363,15 @@ static struct onboard_hub *_find_onboard_hub(struct device *dev) > > > hub = dev_get_drvdata(&pdev->dev); > > > put_device(&pdev->dev); > > > > > > + /* > > > + * Some boards have device tree nodes for USB hubs supported by this > > > + * driver, but the nodes don't have all properties needed for the driver > > > + * to work properly. Use the absence of the "vdd" supply as an indicator > > > + * of such nodes. > > > + */ > > > + if (!of_get_property(pdev->dev.of_node, "vdd", NULL)) > > > + return ERR_PTR(-ENODEV); > > > > Does this not break your original use case? Don't you want "vdd-supply" > > here? > > Ouch, yes it does (to a certain degree). Thanks for pointing it out. My > sanity check didn't catch this because the platform driver still probes > successfully and powers the hub on. > > > That said, this seems like the wrong property to look for both in > > principle and as it is described as optional by the binding: > > > > Documentation/devicetree/bindings/usb/realtek,rts5411.yaml > > > > It seems that you should use the compatible property and check that it > > holds one of the expected values: > > > > - usbbda,5411 > > - usbbda,411 > > > > rather than treat every hub node as describing a realtek hub (AFAIK, > > there is no generic binding for this yet). > > The driver only probes for specific hub models, among them the Microchip > USB2514B hub with which Stefan encountered the regression [1]. > > My initial assumption when writing this driver was that the existence of > a node for a supported hub means that the driver should be used. However > the regression encountered by Stefan makes clear that this assumption is > incorrect. It's not common, but a device tree may have nodes for onboard > USB devices, among them hubs (which might become more common with this > driver). Not in all instances the hub nodes were added with the intention > of using this driver for power sequencing the hub (e.g. [2]). Yeah, you can't assume that. The DT bindings for USB has been around since before your onboard-hub driver. > The > compatible string alone doesn't indicate that the onboard_hub driver > should be instantiated for a given hub, which is why I'm using the > existence of "vdd-supply" as indicator. I don't have time to review this in details, but checking for a specific supply like this just seems wrong (as other have since also pointed out in comments to your v2). There could be hubs which just need to deassert a reset pin for example, and some of the bindings do not even mandate a regulator as I mentioned above. Johan