From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58828C433FE for ; Sun, 6 Nov 2022 21:02:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230051AbiKFVCk (ORCPT ); Sun, 6 Nov 2022 16:02:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229566AbiKFVCi (ORCPT ); Sun, 6 Nov 2022 16:02:38 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 940CCFADD for ; Sun, 6 Nov 2022 13:02:36 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 4198AB80D17 for ; Sun, 6 Nov 2022 21:02:35 +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 Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Yuji Ishikawa , Jiho Chu , Daniel Stone , Tvrtko Ursulin , Jeffrey Hugo , Christoph Hellwig , Kevin Hilman , Jagan Teki , Jacek Lawrynowicz , Maciej Kwapulinski , Stanislaw Gruszka , Randy Dunlap 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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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