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=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 ACA80C43387 for ; Wed, 9 Jan 2019 12:00:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C37B206BA for ; Wed, 9 Jan 2019 12:00:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547035221; bh=TwI3gTLhbBNd1cYXCGa3vZ8P336E2Tv4RllKn2O0a5A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=vBp3MINairlpqtxiFdJ3PWqpu6rZcSUY7DDLWjfXZtMy7YVK8qr2Alc0dXpNeQjhg 2GzsUW2FHTYwnbJRccn+gX0t471JbFUBufVy+C7q95wVz643D+qRxQpRDY4KLy5Ju4 PqtH/oILqqdOyIW9a6eAajh18s9c1k0VU1Igq8QU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730252AbfAIMAU (ORCPT ); Wed, 9 Jan 2019 07:00:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:35802 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729603AbfAIMAU (ORCPT ); Wed, 9 Jan 2019 07:00:20 -0500 Received: from bbrezillon (91-160-177-164.subs.proxad.net [91.160.177.164]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 259CE206B6; Wed, 9 Jan 2019 12:00:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547035219; bh=TwI3gTLhbBNd1cYXCGa3vZ8P336E2Tv4RllKn2O0a5A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=h2gWqV+Ilp+6yZbP7H4pV+YOZWQNGM0OaA5DRrcRyOB8ax8QxplhOo5uo9kX+pYQx kQ85VIt3cmJNGeXwsji2tNiOsWh6hP30mJdYUcZFW411LwzirW7xXD0D9wa41r1/6D +bugV8XiOFX/FbOhH/RvQnP1PxTQxSOv1bGRqaT8= Date: Wed, 9 Jan 2019 13:00:08 +0100 From: Boris Brezillon To: Peter Rosin Cc: "linux-kernel@vger.kernel.org" , Alexandre Belloni , David Airlie , Nicolas Ferre , "dri-devel@lists.freedesktop.org" , Boris Brezillon , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH] drm/atmel-hlcdc: prevent divide by zero Message-ID: <20190109125833.0af5dc52@bbrezillon> In-Reply-To: <9b73f5fa-e5c2-ea55-8d96-be6de8a1f34a@axentia.se> References: <20190108123129.20031-1-peda@axentia.se> <20190109101224.GT21184@phenom.ffwll.local> <9b73f5fa-e5c2-ea55-8d96-be6de8a1f34a@axentia.se> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 9 Jan 2019 11:37:19 +0000 Peter Rosin wrote: > On 2019-01-09 11:12, Daniel Vetter wrote: > > On Tue, Jan 08, 2019 at 12:31:36PM +0000, Peter Rosin wrote: > >> While trying to temporarily hide a plane, one thing that was attempted > >> was to call (from libdrm) > >> > >> drmModeSetPlane(fd, plane_id, crtc_id, fb_id, 0, > >> 0, 0, 0, 0, 0, 0, 0, 0); > >> > >> This call causes a pair of "Division by zero in kernel." messages. Kill > >> those messages, but preserve the current behaviour that also happen to > >> make the plane disappear with the above call. > >> > >> Signed-off-by: Peter Rosin > >> --- > >> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 14 ++++++++++---- > >> 1 file changed, 10 insertions(+), 4 deletions(-) > >> > >> Side note, when comparing with drm_atomic_helper_check_plane_state(), I get > >> the feeling that the src rect should be clipped together with the crtc rect > >> if/when clipping is needed. That function calls drm_rect_clip_scaled(), and > >> the equivalent does not seem to happen here. Should clipping be performed > >> on the src rect? > > > > Any reasons atmel can't switch over to that helper? Would compute a nice > > ->visible state variable for you ... > > -Daniel > > I have not researched that, and as stated above, I was not sure if that was the > correct approach to begin with. Boris, any insights? You can look at vc4_plane.c if you want an example of how this helper can be used to get clipped dimensions of the plane. > Does this code predate the > helper or something? Yes, and I must admit I'm not actively maintaining the driver, so there are probably a few other things we could simplify by using generic helpers. > > Maybe there's some register bit that hides a plane explicitly, matching the > ->visible state variable? I haven't looked at that either... I don't think so, but you can simply disable the plane when ->visible is false.