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 DD087C5DF6A for ; Fri, 14 Aug 2026 20:36:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7FED010E5A4; Fri, 14 Aug 2026 20:36:03 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="bI/f9W7a"; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id F29A410E5A4 for ; Fri, 14 Aug 2026 20:36:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1786739761; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y8HxtGS/+pDsEWZq9YYRCPV84sZrTTgU1WrgrxJbu3s=; b=bI/f9W7aDnIArJRY6Yk9qXj1LeqD0YU5zpFvWh+b9X/bl/4VuGQ9WFkAqHO4O/pjfidrw3 aX1fkG3wbQ1wQ807z2f1eTR8pcIjRinJOdic1E3jM6nAwXK7x5hdU/Z3zjYs0MnMnCS+wV F0ImetPhF3aojyhIODLtcdOVw8W/45k= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-553-OoJM1A43PeiGF1bcosKBrg-1; Fri, 14 Aug 2026 16:35:57 -0400 X-MC-Unique: OoJM1A43PeiGF1bcosKBrg-1 X-Mimecast-MFC-AGG-ID: OoJM1A43PeiGF1bcosKBrg_1786739754 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AC0B919560B5; Fri, 14 Aug 2026 20:35:53 +0000 (UTC) Received: from GoldenWind.lan (unknown [10.22.64.233]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 12FBC197751A; Fri, 14 Aug 2026 20:35:49 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, freedreno@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, nouveau@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-sunxi@lists.linux.dev, asahi@lists.linux.dev, linux-stm32@st-md-mailman.stormreply.com, linux-samsung-soc@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, intel-gfx@lists.freedesktop.org, linux-aspeed@lists.ozlabs.org, linux-rockchip@lists.infradead.org, linux-tegra@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-mips@vger.kernel.org, amd-gfx@lists.freedesktop.org, spice-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, imx@lists.linux.dev Subject: [PATCH 1/5] drm/vblank: Add drm_device.has_hw_vblank Date: Fri, 14 Aug 2026 16:35:29 -0400 Message-ID: <20260814203542.1405135-2-lyude@redhat.com> In-Reply-To: <20260814203542.1405135-1-lyude@redhat.com> References: <20260814203542.1405135-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: nQXqhf8qqu9PecV_LXhColNNaw2ZBLvwxgDfr2W49OI_1786739754 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" Currently the way we check if a driver supports hardware vblanks or not is actually funny and cursed! Likely because it predates KMS. As it turns out, we only check dev->num_crtcs to see if we have vblank support. Why? Because it doesn't actually represent the number of CRTCs on the device, unless drm_vblank_init() has been called - which sets dev->num_crtcs. And as it turns out, this is the second place we keep track of the number of CRTCs we have. Let's clean this up by starting with adding a variable specifically for tracking whether drm_vblank_init() has been called or not. Signed-off-by: Lyude Paul --- drivers/gpu/drm/drm_vblank.c | 3 ++- include/drm/drm_device.h | 7 +++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index f90fb2d13e423..d317148af8cb3 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -557,6 +557,7 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) if (!dev->vblank) return -ENOMEM; + dev->has_hw_vblank = true; dev->num_crtcs = num_crtcs; for (i = 0; i < num_crtcs; i++) { @@ -600,7 +601,7 @@ EXPORT_SYMBOL(drm_vblank_init); */ bool drm_dev_has_vblank(const struct drm_device *dev) { - return dev->num_crtcs != 0; + return dev->has_hw_vblank; } EXPORT_SYMBOL(drm_dev_has_vblank); diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index 768a8dae83c52..2df08c756afd3 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -287,6 +287,13 @@ struct drm_device { */ struct drm_vblank_crtc *vblank; + /** + * @has_hw_vblank: + * + * Has the driver called drm_vblank_init() to setup hardware vblank support? + */ + bool has_hw_vblank; + /** * @vblank_time_lock: * -- 2.55.0