From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1629C326956 for ; Thu, 13 Nov 2025 22:52:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763074330; cv=none; b=tmuP9lddFfPgxYRkb2m+G8oeVdGY4izqKXGBfh3D2FekCL5LUvfap+8ARK6jT2WGI5KEsvs2SFKVBaq9nw/fjIF52TKzvWXmlhOMSJPIL+rqj3x1wF/UdTs3jhnfZ523Jz07Wj14sNIcOQyTLdZBAKmInAqldJovMhIFa4OeeJE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763074330; c=relaxed/simple; bh=uxfWYm2IiB5CYLgZAe3OK8bbpAHUzhkYl+A3UNQFUiM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DHM4uFUM1Y9Lhk3wSnAypKv5UNp8j/vbaPav+Uq/+flugth3ESWuYqzTOtpU3+ShRkDMHtF8spUA9c8/EhgmRlRWEAIwJRhraDYe8BOpHNJvtD2LBN0G/1i0e1FAb1Al64E7Bb7yVzj/CFDB2UrGFDx0HLLB7gSrajo84Srw7y0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=l53zFpgJ; arc=none smtp.client-ip=95.215.58.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="l53zFpgJ" Message-ID: <680bee12-6bac-4634-8a02-4b1717a90aa2@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763074325; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lAcq6yCMhqcbVdlrD5DJA1ON0xOcPq1mCDvRh/oVcgU=; b=l53zFpgJKxgCQ/zXvSEBEODjrtDNlrSyxGUEMGhWwkFoJoSs24T4cr58w2KnX9EUD5Dy9o pe9TwLkoUQWLQBVoR4H8ukOuSl9spAWltkUNjcm4rd9Qu99+vR42TfAJ3IOxqgr6Fk3n2S fmDE4YdWsII3G2RAvEbp0vXY9tza4wk= Date: Thu, 13 Nov 2025 17:51:57 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 2/3] drm: zynqmp: Make the video plane primary To: "Klymenko, Anatoliy" , Laurent Pinchart , Tomi Valkeinen , "dri-devel@lists.freedesktop.org" Cc: "linux-kernel@vger.kernel.org" , Mike Looijmans , David Airlie , Thomas Zimmermann , Maarten Lankhorst , Maxime Ripard , "linux-arm-kernel@lists.infradead.org" , Simona Vetter , "Simek, Michal" References: <20251113203715.2768107-1-sean.anderson@linux.dev> <20251113203715.2768107-3-sean.anderson@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 11/13/25 17:45, Klymenko, Anatoliy wrote: > [AMD Official Use Only - AMD Internal Distribution Only] > > Hi Sean, > > Thanks a lot for the patch (and tackling the alpha issue in general) > >> -----Original Message----- >> From: Sean Anderson >> Sent: Thursday, November 13, 2025 12:37 PM >> To: Laurent Pinchart ; Tomi Valkeinen >> ; dri-devel@lists.freedesktop.org >> Cc: linux-kernel@vger.kernel.org; Mike Looijmans ; >> David Airlie ; Thomas Zimmermann >> ; Maarten Lankhorst >> ; Klymenko, Anatoliy >> ; Maxime Ripard ; linux- >> arm-kernel@lists.infradead.org; Simona Vetter ; Simek, >> Michal ; Sean Anderson >> >> Subject: [PATCH 2/3] drm: zynqmp: Make the video plane primary >> >> Caution: This message originated from an External Source. Use proper caution >> when opening attachments, clicking links, or responding. >> >> >> The zynqmp has two planes: "video" and "graphics". The video plane >> >> - Is on the bottom (zpos=0) (except when chroma keying as the master plane) >> - Supports "live" input (e.g. from an external source) >> - Supports RGB, YUV, and YCbCr formats, including XRGB8888 >> - Does not support transparency, except via chroma keying (colorkey) >> - Must cover the entire screen (translation/resizing not supported) >> >> The graphics plane >> >> - Is on the top (zpos=1) >> - Supports "live" input (e.g. from an external source) >> - Supports RGB and YUV444 formats, but not XRGB8888 >> - Supports transparency either via >> - Global alpha channel, which disables per-pixel alpha when enabled >> - Per-pixel alpha, which cannot be used with global alpha >> - Chroma keying (colorkey) >> - Must cover the entire screen (translation/resizing not supported) >> >> Currently the graphics plane is the primary plane. Make the video plane >> the primary plane: >> >> - The video plane supports XRGB8888, which is the default 24-bit >> colorspace for X. This results in improved performance when compared >> to RGB565. >> - The graphics plane can be used as an overlay because it has a higher >> z-pos and supports a per-pixel alpha channel. Unfortunately, clients >> like weston cannot currently take advantage of this because they >> expect overlay planes to support translation/resizing. >> >> One downside to this approach could be that the graphics plane has worse >> support for YUV and YCBCr, so it may be more difficult to compose video > > Not just more difficult but practically impossible: > 1. GFX (in Xilinx terminology) plane doesn't support pixel upscaling, so > no support for NV12, YUY2 and other common video pixel formats. > 2. Both planes are unscalable, this means we can only output native > display resolution video on the top plane, or display thick black frame > around the picture. We are losing GFX masking capabilities. The graphics masking capabilities are the same as they always were. > 3. We won't be able to render subtitles on top of the video. > Probably the only practical video player option remains here is to render > video to a texture and embed it into graphics composition. OK, but none of this is currently possible either because of the global alpha setting. So do you have a specific program in mind that plays video and will do it with an "underlay" plane? >> streams into the window of a media player. However, no existing software >> could rely on this because there is no way to enable the per-pixel alpha >> channel when the graphics plane is enabled. This makes it impossible to > > This situation is a driver bug not a fatum. And yet the driver bug provides ample evidence that no one is doing this, so we don't need to worry about it. --Sean > Per pixel alpha blending works > just fine if we disable global alpha. We just need to avoid enabling it when > we have alpha capable GFX plane format. > >> "carve out" an area in the graphics plane where the video plane shows >> through. This limitation is addressed in the next patch, but it means we >> do not need to worry about compatibility in this area. >> >> An alternate approach could be to pretend that the graphics plane >> supports XRGB8888 by using the supported ARGB8888 mode instead and >> enabling the global alpha channel. However, this would rule out ever >> using the per-pixel alpha channel. >> >> Signed-off-by: Sean Anderson >> --- >> >> drivers/gpu/drm/xlnx/zynqmp_kms.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c >> b/drivers/gpu/drm/xlnx/zynqmp_kms.c >> index c80a2d4034f3..456ada9ac003 100644 >> --- a/drivers/gpu/drm/xlnx/zynqmp_kms.c >> +++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c >> @@ -161,8 +161,8 @@ static int zynqmp_dpsub_create_planes(struct >> zynqmp_dpsub *dpsub) >> if (!formats) >> return -ENOMEM; >> >> - /* Graphics layer is primary, and video layer is overlay. */ >> - type = i == ZYNQMP_DPSUB_LAYER_VID >> + /* Graphics layer is overlay, and video layer is primary. */ >> + type = i == ZYNQMP_DPSUB_LAYER_GFX >> ? DRM_PLANE_TYPE_OVERLAY : >> DRM_PLANE_TYPE_PRIMARY; >> ret = drm_universal_plane_init(&dpsub->drm->dev, plane, 0, >> &zynqmp_dpsub_plane_funcs, >> @@ -322,7 +322,7 @@ static const struct drm_crtc_funcs >> zynqmp_dpsub_crtc_funcs = { >> >> static int zynqmp_dpsub_create_crtc(struct zynqmp_dpsub *dpsub) >> { >> - struct drm_plane *plane = &dpsub->drm- >> >planes[ZYNQMP_DPSUB_LAYER_GFX]; >> + struct drm_plane *plane = &dpsub->drm- >> >planes[ZYNQMP_DPSUB_LAYER_VID]; >> struct drm_crtc *crtc = &dpsub->drm->crtc; >> int ret; >> >> -- >> 2.35.1.1320.gc452695387.dirty > > Thank you, > Anatoliy