From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp02.smtpout.orange.fr ([80.12.242.124]:50421 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752293AbcCGQdi (ORCPT ); Mon, 7 Mar 2016 11:33:38 -0500 From: Robert Jarzmik To: Pawel Osciak , Marek Szyprowski , Kyungmin Park Cc: Hans Verkuil , Mauro Carvalho Chehab , Linux Media Mailing List Subject: videobuf2-dma-sg and multiple planes semantics Date: Mon, 07 Mar 2016 17:33:26 +0100 Message-ID: <87y49uuu21.fsf@belgarion.home> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-media-owner@vger.kernel.org List-ID: Hi, I've been converting pxa_camera driver from videobuf to videobuf2, and I have a question about multiple plane semantics. I have a case where I have 3 planes for a yuv422 capture : - 1 Y plane (total_size / 2 bytes) - 1 U plane (total_size / 4 bytes) - 1 V plane (total_size / 4 bytes) I would have expected vb2_dma_sg_plane_desc(vb, i) to return me 3 different sg_tables, one for each plane. I would have been then able to feed them to 3 dmaengine channels (this is the case for pxa27x platform), so that the 3 planes are filled in concurrently. My understanding is that videobuf2-dma-sg has only 1 sg_table, which seems to be enforced by vb2_dma_sg_cookie(), so the question is : is it on purpose, and how do the multiple planes are handled within videobuf2-dma-sg ? Cheers. -- Robert