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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 21050C4345F for ; Wed, 17 Apr 2024 09:28:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4C1E710F4E3; Wed, 17 Apr 2024 09:28:20 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="t4oQDr5h"; dkim-atps=neutral Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id C941E10F368 for ; Wed, 17 Apr 2024 09:28:18 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 8A02DCE12CA; Wed, 17 Apr 2024 09:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61A6FC072AA; Wed, 17 Apr 2024 09:28:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713346094; bh=E4NxfokkS134BQqYi4l9d24KTL7bidk0mUYpB0lh7pY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t4oQDr5h3H7bnXCR4Cr7SVoVflqDgciWtzCI+XZ1BRaSCxfdTgH/0Db67Z3HjnZGi M2rQLFsltdSnsvpgsnvu5zUe2b/7uWjUEE4xAL9nwxKI2yUJkdlYAtALzvMkg+FYcm ltWSGy0EFIIYcm6hQwSdQmADIwIeSTKtlluGXBm0= Date: Wed, 17 Apr 2024 11:28:12 +0200 From: Greg Kroah-Hartman To: Herman van Hazendonk Cc: "Rafael J. Wysocki" , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Linus Walleij Subject: Re: [PATCH] component: Support masters with no subcomponents Message-ID: <2024041713-devalue-unsightly-56cb@gregkh> References: <20240417-component-dummy-v1-1-b0854665c760@herrie.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240417-component-dummy-v1-1-b0854665c760@herrie.org> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed, Apr 17, 2024 at 11:12:09AM +0200, Herman van Hazendonk wrote: > This happens in the MSM DRM driver when it is used > without any subcomponents, which is a special corner > case. > > If the MDP4 is used with nothing but the LVDS display, > we get this problem that no components are found since > the LVDS is part of the MDP4 itself. > > We cannot use a NULL match, so create a dummy match > with no components for this case so the driver will > still probe nicely without adding a secondary > complicated probe() path to the MSM DRM driver. > > Signed-off-by: Linus Walleij > Signed-off-by: Herman van Hazendonk > --- > This happens in the MSM DRM driver when it is used > without any subcomponents, which is a special corner > case. > > If the MDP4 is used with nothing but the LVDS display, > we get this problem that no components are found since > the LVDS is part of the MDP4 itself. > > We cannot use a NULL match, so create a dummy match > with no components for this case so the driver will > still probe nicely without adding a secondary > complicated probe() path to the MSM DRM driver. Why is the text duplicated here twice? Also, why are you adding complexity to the core for something that has not been an issue for any other device? Shouldn't the driver need to handle this instead if it wishes to use the component code? Will this change affect any other in-tree user? thanks, greg k-h