From patchwork Tue Jan 3 15:27:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Paul X-Patchwork-Id: 13087616 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 26850C46467 for ; Tue, 3 Jan 2023 15:27:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3DEAA10E1F9; Tue, 3 Jan 2023 15:27:43 +0000 (UTC) Received: from mail-vs1-xe2a.google.com (mail-vs1-xe2a.google.com [IPv6:2607:f8b0:4864:20::e2a]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9663010E1F9 for ; Tue, 3 Jan 2023 15:27:41 +0000 (UTC) Received: by mail-vs1-xe2a.google.com with SMTP id h27so18335983vsq.3 for ; Tue, 03 Jan 2023 07:27:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poorly.run; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=lYzp1sgJFzIzjeht/At2SP3CFYWumSuwKnH+2GC5NAE=; b=D+WW65t2fkGC+NXKatGmDTA4QkluHWXv2piKuETEy6ykakE1cnAiAkQwlyT9ivCuQi xoBJjTkEDN6Ko6OMYH2wDYNu7iNBOwqdK16+GmcLinRhaDhq9Tn9QKaN+r3tpaaTQHdJ 7JJsPkMOGz9UNnDNHLFvVxo/RVA338IlwTp1byj4QTjiJ53fSmzc2Z+bea+/cI2ZAZKh Ff4DZu1cPpzaH49gi6bWaDgxB6DeeSMCC4fgUUncE6xT6sCVWamSHAR5nvXgbbusFRb4 CWLF4EwnoZDiCviyPC2gBpHTICPdQbg+IVHZ8TIqhaFBOLKMgVabW7CQCdebqYQb8lat Fl6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=lYzp1sgJFzIzjeht/At2SP3CFYWumSuwKnH+2GC5NAE=; b=rEqhXpP/xaF4BqkkmgVSLyDcA3rBv9Ei/HmJQfKk9DkG2eMkQuJwLvf11rlnCzlrVZ LsqepcYA1ltiNCDqVj/eLYSr08TWtwY5XfpbQYAq7I9yEjSnzBgMoOU+J4Vm9JED9pSc KO1aSwYL2Wp7XU9KLprOB9xbNVIBHipOgbB3/jDMcx1IMlYpi03giI9xstVx9KRCnD/4 trfff0BxBfjgwkQQlLOSiL/+XWOLuvzbaSGNQZnXQOMhVNcIxX9+ubipoCzJmnq3ppqj Y4I0Jwpdm30DKmN6gT9pGtJFE1d6ckfCmIL5ghzfZREKFy6dlLQi8TamwoVXY5rIR2y1 XaTg== X-Gm-Message-State: AFqh2kqRKLxMXHCwiHC7RX4VZDH81dHIOvNWvyM6bZ22fNB1l0MikliL fEJwWLMcvm0xgA61f3fBjxNUWWb+XkhVHmVi X-Google-Smtp-Source: AMrXdXuUejN2i/M+iPxnzkQ6f9kMoqvm/2f91BmH+39GP/a+DIRlO1GUT4LJMT7FqiBippMVLfNEwg== X-Received: by 2002:a05:6102:a4a:b0:3cb:93d:406f with SMTP id i10-20020a0561020a4a00b003cb093d406fmr11924966vss.32.1672759659941; Tue, 03 Jan 2023 07:27:39 -0800 (PST) Received: from localhost (200.234.86.34.bc.googleusercontent.com. [34.86.234.200]) by smtp.gmail.com with ESMTPSA id s6-20020a05620a254600b007055fa93060sm2528510qko.79.2023.01.03.07.27.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Jan 2023 07:27:38 -0800 (PST) From: Sean Paul To: dri-devel@lists.freedesktop.org Subject: [PATCH] drm/docs: Explicitly document default CRTC background behavior Date: Tue, 3 Jan 2023 15:27:38 +0000 Message-Id: <20230103152738.1213785-1-sean@poorly.run> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog MIME-Version: 1.0 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: , Cc: Sean Paul Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Sean Paul Add a paragraph explaining that the default behavior for areas which are not covered by planes or where planes are blending with the CRTC background, is black. This is alluded to in the "pixel blend mode" property docs, but not called out explicitly. Signed-off-by: Sean Paul Reviewed-by: Simon Ser --- drivers/gpu/drm/drm_plane.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 33357629a7f5..24e7998d1731 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -46,6 +46,11 @@ * properties that specify how the pixels are positioned and blended, like * rotation or Z-position. All these properties are stored in &drm_plane_state. * + * Unless explicitly specified (via CRTC property or otherwise), the active area + * of a CRTC will be black by default. This means portions of the active area + * which are not covered by a plane will be black, and alpha blending of any + * planes with the CRTC background will blend with black at the lowest zpos. + * * To create a plane, a KMS drivers allocates and zeroes an instances of * &struct drm_plane (possibly as part of a larger structure) and registers it * with a call to drm_universal_plane_init().