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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3E2E8C4332F for ; Tue, 14 Sep 2021 14:34:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 223AF610A2 for ; Tue, 14 Sep 2021 14:34:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233501AbhINOfc (ORCPT ); Tue, 14 Sep 2021 10:35:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233437AbhINOfa (ORCPT ); Tue, 14 Sep 2021 10:35:30 -0400 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 185B9C061574 for ; Tue, 14 Sep 2021 07:34:13 -0700 (PDT) Received: by mail-wr1-x431.google.com with SMTP id m9so20633123wrb.1 for ; Tue, 14 Sep 2021 07:34:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=umuxgc7vOkVRRThGNSeYBWaUdtkpW3a8Wcpiqh4MYbc=; b=jD8ytdC9p3Oynfkv/tjifDU0me0iiGMF/3m6ml50oggD+O0K3DOQyfqsmqlDIQDoCH VwUYp0Wb4PDbLm7l1Rss7xsPk7TETZWw1YT27aWApJa4xAgZAyp649HE8fcODei/OAa8 jR3n5M6hKglM0yOeQkIKKlBnFvQX45NxCLTRc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=umuxgc7vOkVRRThGNSeYBWaUdtkpW3a8Wcpiqh4MYbc=; b=oX0F8MVNPef9MIRWqBlaB2BYjGiLDwQonNef4+tV7cn9WIGslr3X3dP5sc/k5pDURA 7uUCVjV6irP7aV5oGtEpcuYgKEkCXUJfQ4ahoEaYeXbMOWP8fmv3K2Eet9XDPSF8K8yP c9rrj/FsrDhw2wh9aOlQh2GqymH+5S91mmYJdGy2Bp9j8CzAvSNs5cSxsMv7iskg+PoE ja/R/MRoNL+nPMcKfefmTRgqSSaAZKIfk3uNk5r/LNjdrN9/LYLqdM7CVPKjENcCP4lv 5gE8lCgxphtcJURXqyEHmw2ybaCyQa6hSUOymZ84Ay5zUFMuPvmFS2+ziYlIuRZfxKK1 vAGQ== X-Gm-Message-State: AOAM533tO+UL4JgD6KPJh0mTpeRYZ4WXFXpCVdy2fHIga45y8rQcfsg1 jFm8doU1bXs7oPlCVBEbFwlRSQ== X-Google-Smtp-Source: ABdhPJyNO/LULB90/yEEwF9ND2QwLBtsq4PXK/5714kKpXeCbJIv1rAbuAXKev+VHEAfFBzqOw58yg== X-Received: by 2002:adf:e349:: with SMTP id n9mr19840313wrj.326.1631630051643; Tue, 14 Sep 2021 07:34:11 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id d9sm13255576wrb.36.2021.09.14.07.34.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Sep 2021 07:34:11 -0700 (PDT) Date: Tue, 14 Sep 2021 16:34:08 +0200 From: Daniel Vetter To: Maxime Ripard Cc: dri-devel@lists.freedesktop.org, Daniel Vetter , David Airlie , Maarten Lankhorst , Thomas Zimmermann , Emma Anholt , linux-rpi-kernel@lists.infradead.org, Dave Stevenson , Phil Elwell , Tim Gover , Dom Cobley , Sam Ravnborg , Nicolas Saenz Julienne , bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/3] drm/vc4: hdmi: Actually check for the connector status in hotplug Message-ID: Mail-Followup-To: Maxime Ripard , dri-devel@lists.freedesktop.org, Daniel Vetter , David Airlie , Maarten Lankhorst , Thomas Zimmermann , Emma Anholt , linux-rpi-kernel@lists.infradead.org, Dave Stevenson , Phil Elwell , Tim Gover , Dom Cobley , Sam Ravnborg , Nicolas Saenz Julienne , bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org References: <20210914101724.266570-1-maxime@cerno.tech> <20210914101724.266570-3-maxime@cerno.tech> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210914101724.266570-3-maxime@cerno.tech> X-Operating-System: Linux phenom 5.10.0-8-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 14, 2021 at 12:17:24PM +0200, Maxime Ripard wrote: > The drm_helper_hpd_irq_event() documentation states that this function > is "useful for drivers which can't or don't track hotplug interrupts for > each connector." and that "Drivers which support hotplug interrupts for > each connector individually and which have a more fine-grained detect > logic should bypass this code and directly call > drm_kms_helper_hotplug_event()". This is thus what we ended-up doing. > > However, what this actually means, and is further explained in the > drm_kms_helper_hotplug_event() documentation, is that > drm_kms_helper_hotplug_event() should be called by drivers that can > track the connection status change, and if it has changed we should call > that function. > > This underlying expectation we failed to provide is that the caller of > drm_kms_helper_hotplug_event() should call drm_helper_probe_detect() to > probe the new status of the connector. > > Since we didn't do it, it meant that even though we were sending the > notification to user-space and the DRM clients that something changed we > never probed or updated our internal connector status ourselves. > > This went mostly unnoticed since the detect callback usually doesn't > have any side-effect. Also, if we were using the DRM fbdev emulation > (which is a DRM client), or any user-space application that can deal > with hotplug events, chances are they would react to the hotplug event > by probing the connector status eventually. > > However, now that we have to enable the scrambler in detect() if it was > enabled it has a side effect, and an application such as Kodi or > modetest doesn't deal with hotplug events. This resulted with a black > screen when Kodi or modetest was running when a screen was disconnected > and then reconnected, or switched off and on. Uh, why are you running this scrambler restore in your probe function? I guess it works, but most drivers that do expensive hotplug restore to handle the "no black screen for replug" use-case handle that in their own dedicated code. But those also tend to have per-output hpd interrupt sources, so maybe that's why? -Daniel > > Signed-off-by: Maxime Ripard > --- > drivers/gpu/drm/vc4/vc4_hdmi.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c > index a3dbd1fdff7d..d9e001b9314f 100644 > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c > @@ -1578,10 +1578,11 @@ static int vc4_hdmi_audio_init(struct vc4_hdmi *vc4_hdmi) > static irqreturn_t vc4_hdmi_hpd_irq_thread(int irq, void *priv) > { > struct vc4_hdmi *vc4_hdmi = priv; > - struct drm_device *dev = vc4_hdmi->connector.dev; > + struct drm_connector *connector = &vc4_hdmi->connector; > + struct drm_device *dev = connector->dev; > > if (dev && dev->registered) > - drm_kms_helper_hotplug_event(dev); > + drm_connector_helper_hpd_irq_event(connector); > > return IRQ_HANDLED; > } > -- > 2.31.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch