From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 4EA16199FCD for ; Thu, 31 Oct 2024 10:42:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730371351; cv=none; b=pdzzlaEuXVw2+T5RSc+oVjLzhbsFrnJiA2cIBaIxfQK0ZCtKYBO9hqdsuAi672/Cs3KFXDoTGwcRSUST2ublBTtTnDquuLEpuqDyFqmbWDubo2L+QtddqYtuTYIbrlg97X+/2IO1mGVVC8PoSlL08IMXwTlGQviguOScq7xWD9c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730371351; c=relaxed/simple; bh=Tb2AAyxawFX+WuFvZpBTwXf7Ij/FAORlAwfN5kr3Z4Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iSztFCOy1Mjr5i7GIcuGrnNuhZugTg61bprPTrjVuROqoX5YhGPzz7v3zOptiFSB7n2L3DmNxgql2mL2TxgSX5Wu5/AROD3CXFrqQdUSsPCSGW9nDiuBJmX206o0iutIOShYDd1rQ2jxcg2dnv3wJ4IrDQOuVNd1ejw7dt+X+dY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=ipfmD2k9; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ipfmD2k9" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 6FB479EC; Thu, 31 Oct 2024 11:42:23 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1730371343; bh=Tb2AAyxawFX+WuFvZpBTwXf7Ij/FAORlAwfN5kr3Z4Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ipfmD2k9hrw7BRVh4ParJIsL3apuOpHhsYHzT5h26zqOMlq69Hmd8D4V+jnmkUCnX Dc79/n20Mn0gYLuvIzykpO/zXxGFyGv/6rbXOXKEA4CxwtmVyU87G2DCIy8RmsRjZl 7ejwEvs89/NIOZE2nMPKmnMjT6o0KZjXSo7bD0DQ= Date: Thu, 31 Oct 2024 12:42:19 +0200 From: Laurent Pinchart To: Hans Verkuil Cc: Linux Media Mailing List , Nicolas Dufresne Subject: Re: [PATCH] Documentation: media: improve V4L2_CID_MIN_BUFFERS_FOR_*, doc Message-ID: <20241031104219.GF2473@pendragon.ideasonboard.com> References: <93d078e5-deba-4060-a32e-94bce677453c@xs4all.nl> <20241031101141.GD2473@pendragon.ideasonboard.com> <2a61ded3-4cea-4a1a-9d16-aa74dbb22f74@xs4all.nl> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2a61ded3-4cea-4a1a-9d16-aa74dbb22f74@xs4all.nl> On Thu, Oct 31, 2024 at 11:26:47AM +0100, Hans Verkuil wrote: > On 10/31/24 11:11, Laurent Pinchart wrote: > > Hi Hans, > > > > Thank you for the patch. > > > > On Thu, Oct 31, 2024 at 08:50:04AM +0100, Hans Verkuil wrote: > >> Clearly state that the V4L2_CID_MIN_BUFFERS_FOR_OUTPUT and > >> V4L2_CID_MIN_BUFFERS_FOR_CAPTURE controls are required for > >> stateful codecs. > > > > Wouldn't it be better for this kind of information to be centralized in > > a stateful decoder document ? That would make it easier for developers > > to see all they need to implement. Otherwise they would need to read > > through the whole documentation to pick the parts of the API they need > > to support in their drivers. > > It's also already mentioned in the documentation for the stateful de/encoders here: > > https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/dev-mem2mem.html OK, then it's fine to have it here too I think. Reviewed-by: Laurent Pinchart > > Also, once this vicodec patch is merged: > > https://patchwork.linuxtv.org/project/linux-media/patch/1dd09050-40ca-4c5b-b985-819731140388@xs4all.nl/ > > I plan to push v4l2-compliance patches that explicitly test for the presence of > these controls and fail if they are missing (like they are now in vicodec). > > >> Signed-off-by: Hans Verkuil > >> --- > >> Documentation/userspace-api/media/v4l/control.rst | 6 ++++-- > >> 1 file changed, 4 insertions(+), 2 deletions(-) > >> > >> diff --git a/Documentation/userspace-api/media/v4l/control.rst b/Documentation/userspace-api/media/v4l/control.rst > >> index 57893814a1e5..9253cc946f02 100644 > >> --- a/Documentation/userspace-api/media/v4l/control.rst > >> +++ b/Documentation/userspace-api/media/v4l/control.rst > >> @@ -290,13 +290,15 @@ Control IDs > >> This is a read-only control that can be read by the application and > >> used as a hint to determine the number of CAPTURE buffers to pass to > >> REQBUFS. The value is the minimum number of CAPTURE buffers that is > >> - necessary for hardware to work. > >> + necessary for hardware to work. This control is required for stateful > >> + decoders. > >> > >> ``V4L2_CID_MIN_BUFFERS_FOR_OUTPUT`` ``(integer)`` > >> This is a read-only control that can be read by the application and > >> used as a hint to determine the number of OUTPUT buffers to pass to > >> REQBUFS. The value is the minimum number of OUTPUT buffers that is > >> - necessary for hardware to work. > >> + necessary for hardware to work. This control is required for stateful > >> + encoders. > >> > >> .. _v4l2-alpha-component: > >> -- Regards, Laurent Pinchart