From patchwork Sun Nov 6 21:02:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oded Gabbay X-Patchwork-Id: 13033568 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 1DD92C4332F for ; Sun, 6 Nov 2022 21:02:40 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1A32210E04D; Sun, 6 Nov 2022 21:02:39 +0000 (UTC) Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7079610E04D for ; Sun, 6 Nov 2022 21:02:35 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7E07160CF1; Sun, 6 Nov 2022 21:02:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE5DC433D7; Sun, 6 Nov 2022 21:02:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667768553; bh=EXvwdhWEYV7UJ2h0xFwZgcbB4zy2TYFGbCvTW03tHYU=; h=From:To:Cc:Subject:Date:From; b=GprBHDGEFAa8bq7NcFH9F6bzocK/wwk4LpOUsP86Ft/pnzakOV/s7rhPdDIb4LvoB b6bMd37UQcYM80/6j6/hEp82DmnwLbT5qI0ba8NmhZGbm91FwwElyzR8BTsFQZwknL DJVjSPfYJSSlRtjvvz5INLEKCXy/W6Twpl3tCl1p/kmKLXLZFeV+VgU4+nepV7EbPW b3orOmpSRCucQ+nwO6glQMSnMKY5UA35GQb9DdH6P72CxJGNhedkAqo+SrnL0VSxL1 4HUoyZs6G2FkbB59ucvGgI4gtwsMuZmxyz1tvjtVLSWAvSWV6QnYnT8AvjajVhIz2W +jnxmIcA88duA== From: Oded Gabbay To: David Airlie , Daniel Vetter , Arnd Bergmann , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Jason Gunthorpe , John Hubbard , Alex Deucher Subject: [RFC PATCH v3 0/3] new subsystem for compute accelerator devices Date: Sun, 6 Nov 2022 23:02:22 +0200 Message-Id: <20221106210225.2065371-1-ogabbay@kernel.org> X-Mailer: git-send-email 2.25.1 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: Tvrtko Ursulin , Jacek Lawrynowicz , Jeffrey Hugo , Jiho Chu , Randy Dunlap , Christoph Hellwig , Stanislaw Gruszka , Thomas Zimmermann , Kevin Hilman , Yuji Ishikawa , Maciej Kwapulinski , Jagan Teki Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This is the third version of the RFC following the comments given on the second version, but more importantly, following testing done by the VPU driver people and myself. We found out that there is a circular dependency between DRM and accel. DRM calls accel exported symbols during init and when accel devices are registering (all the minor handling), then accel calls DRM exported symbols. Therefore, if the two components are compiled as modules, there is a circular dependency. To overcome this, I have decided to compile the accel core code as part of the DRM kernel module (drm.ko). IMO, this is inline with the spirit of the design choice to have accel reuse the DRM core code and avoid code duplication. Another important change is that I have reverted back to use IDR for minor handling instead of xarray. This is because I have found that xarray doesn't handle well the scenario where you allocate a NULL entry and then exchange it with a real pointer. It appears xarray still considers that entry a "zero" entry. This is unfortunate because DRM works that way (first allocates a NULL entry and then replaces the entry with a real pointer). I decided to revert to IDR because I don't want to hold up these patches, as many people are blocked until the support for accel is merged. The xarray issue should be fixed as a separate patch by either fixing the xarray code or changing how DRM + ACCEL do minor id handling. The patches are in the following repo: https://git.kernel.org/pub/scm/linux/kernel/git/ogabbay/accel.git/log/?h=accel_v3 As in v2, The HEAD of that branch is a commit adding a dummy driver that registers an accel device using the new framework. This can be served as a simple reference. I have checked inserting and removing the dummy driver, and opening and closing /dev/accel/accel0 and nothing got broken :) v1 cover letter: https://lkml.org/lkml/2022/10/22/544 v2 cover letter: https://lore.kernel.org/lkml/20221102203405.1797491-1-ogabbay@kernel.org/T/ Thanks, Oded. Oded Gabbay (3): drivers/accel: define kconfig and register a new major accel: add dedicated minor for accelerator devices drm: initialize accel framework Documentation/admin-guide/devices.txt | 5 + MAINTAINERS | 8 + drivers/Kconfig | 2 + drivers/accel/Kconfig | 24 ++ drivers/accel/drm_accel.c | 322 ++++++++++++++++++++++++++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_drv.c | 102 +++++--- drivers/gpu/drm/drm_file.c | 2 +- drivers/gpu/drm/drm_sysfs.c | 24 +- include/drm/drm_accel.h | 97 ++++++++ include/drm/drm_device.h | 3 + include/drm/drm_drv.h | 8 + include/drm/drm_file.h | 21 +- 13 files changed, 582 insertions(+), 37 deletions(-) create mode 100644 drivers/accel/Kconfig create mode 100644 drivers/accel/drm_accel.c create mode 100644 include/drm/drm_accel.h --- 2.25.1