Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754015AbcJKQ4R (ORCPT ); Tue, 11 Oct 2016 12:56:17 -0400 Received: from mail-io0-f193.google.com ([209.85.223.193]:34328 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752854AbcJKQ4Q (ORCPT ); Tue, 11 Oct 2016 12:56:16 -0400 MIME-Version: 1.0 X-Originating-IP: [2a02:168:56b5:0:ac27:b86c:7764:9429] In-Reply-To: <20161011164751.GB14337@e106950-lin.cambridge.arm.com> References: <1476197648-24918-1-git-send-email-brian.starkey@arm.com> <1476197648-24918-3-git-send-email-brian.starkey@arm.com> <20161011154448.GE20761@phenom.ffwll.local> <20161011164751.GB14337@e106950-lin.cambridge.arm.com> From: Daniel Vetter Date: Tue, 11 Oct 2016 18:56:14 +0200 X-Google-Sender-Auth: Y_70wTCD2U-fIK4XWOAwYFeO1lM Message-ID: Subject: Re: [RFC PATCH 02/11] drm/fb-helper: Skip writeback connectors To: Brian Starkey Cc: dri-devel , Linux Kernel Mailing List , "linux-media@vger.kernel.org" , Liviu Dudau , "Clark, Rob" , Hans Verkuil , Eric Anholt , "Syrjala, Ville" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1786 Lines: 49 On Tue, Oct 11, 2016 at 6:47 PM, Brian Starkey wrote: > On Tue, Oct 11, 2016 at 05:44:48PM +0200, Daniel Vetter wrote: >> >> On Tue, Oct 11, 2016 at 03:53:59PM +0100, Brian Starkey wrote: >>> >>> Writeback connectors aren't much use to the fbdev helpers, as they won't >>> show anything to the user. Skip them when looking for candidate output >>> configurations. >>> >>> Signed-off-by: Brian Starkey >>> --- >>> drivers/gpu/drm/drm_fb_helper.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>> b/drivers/gpu/drm/drm_fb_helper.c >>> index 03414bd..dedf6e7 100644 >>> --- a/drivers/gpu/drm/drm_fb_helper.c >>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>> @@ -2016,6 +2016,10 @@ static int drm_pick_crtcs(struct drm_fb_helper >>> *fb_helper, >>> if (modes[n] == NULL) >>> return best_score; >>> >>> + /* Writeback connectors aren't much use for fbdev */ >>> + if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK) >>> + return best_score; >> >> >> I think we could handle this by always marking writeback connectors as >> disconnected. Userspace and fbdev emulation should then avoid them, >> always. >> -Daniel >> > > Good idea; I'll need to take a closer look at how it would interact > with the probe helper (connector->force etc). > > Are you thinking instead-of or in-addition-to the client cap? I'd be > worried about apps doing strange things and trying to use even > disconnected connectors. Apps shouldn't try to use disconnected connectors, at least by default. I think we wouldn't need the cap in that case. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch