From patchwork Mon Jul 18 07:21:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Airlie X-Patchwork-Id: 12920921 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 49A7DC433EF for ; Mon, 18 Jul 2022 07:23:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233823AbiGRHXK (ORCPT ); Mon, 18 Jul 2022 03:23:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233809AbiGRHXJ (ORCPT ); Mon, 18 Jul 2022 03:23:09 -0400 X-Greylist: delayed 67 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 18 Jul 2022 00:23:08 PDT Received: from us-smtp-delivery-44.mimecast.com (us-smtp-delivery-44.mimecast.com [207.211.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8F2BB17E1D for ; Mon, 18 Jul 2022 00:23:08 -0700 (PDT) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-277-AgST6BwiNTG9NjgWcQgQBg-1; Mon, 18 Jul 2022 03:21:54 -0400 X-MC-Unique: AgST6BwiNTG9NjgWcQgQBg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9F8D7811E80; Mon, 18 Jul 2022 07:21:53 +0000 (UTC) Received: from dreadlord.bne.redhat.com (fdacunha.bne.redhat.com [10.64.0.157]) by smtp.corp.redhat.com (Postfix) with ESMTP id 69304141511A; Mon, 18 Jul 2022 07:21:49 +0000 (UTC) From: Dave Airlie To: torvalds@linux-foundation.org, Jonathan Corbet , linux-doc@vger.kernel.org, gregkh@linuxfoundation.org, Daniel Vetter , mcgrof@kernel.org Cc: linux-kernel@vger.kernel.org, dri-devel@lists.sf.net, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, alsa-devel@alsa-project.org, linux-media@vger.kernel.org, linux-block@vger.kernel.org, Dave Airlie Subject: [PATCH] docs: driver-api: firmware: add driver firmware guidelines. Date: Mon, 18 Jul 2022 17:21:44 +1000 Message-Id: <20220718072144.2699487-1-airlied@gmail.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org From: Dave Airlie A recent snafu where Intel ignored upstream feedback on a firmware change, led to a late rc6 fix being required. In order to avoid this in the future we should document some expectations around linux-firmware. I was originally going to write this for drm, but it seems quite generic advice. I'm cc'ing this quite widely to reach subsystems which use fw a lot. Signed-off-by: Dave Airlie Acked-by: Rodrigo Vivi Acked-by: Luis Chamberlain --- Documentation/driver-api/firmware/core.rst | 1 + .../firmware/firmware-usage-guidelines.rst | 34 +++++++++++++++++++ 2 files changed, 35 insertions(+) create mode 100644 Documentation/driver-api/firmware/firmware-usage-guidelines.rst diff --git a/Documentation/driver-api/firmware/core.rst b/Documentation/driver-api/firmware/core.rst index 1d1688cbc078..803cd574bbd7 100644 --- a/Documentation/driver-api/firmware/core.rst +++ b/Documentation/driver-api/firmware/core.rst @@ -13,4 +13,5 @@ documents these features. direct-fs-lookup fallback-mechanisms lookup-order + firmware-usage-guidelines diff --git a/Documentation/driver-api/firmware/firmware-usage-guidelines.rst b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst new file mode 100644 index 000000000000..34d2412e78c6 --- /dev/null +++ b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst @@ -0,0 +1,34 @@ +=================== +Firmware Guidelines +=================== + +Drivers that use firmware from linux-firmware should attempt to follow +the rules in this guide. + +* Firmware should be versioned with at least a major/minor version. It + is suggested that the firmware files in linux-firmware be named with + some device specific name, and just the major version. The + major/minor/patch versions should be stored in a header in the + firmware file for the driver to detect any non-ABI fixes/issues. The + firmware files in linux-firmware should be overwritten with the newest + compatible major version. Newer major version firmware should remain + compatible with all kernels that load that major number. + +* Users should *not* have to install newer firmware to use existing + hardware when they install a newer kernel. If the hardware isn't + enabled by default or under development, this can be ignored, until + the first kernel release that enables that hardware. This means no + major version bumps without the kernel retaining backwards + compatibility for the older major versions. Minor version bumps + should not introduce new features that newer kernels depend on + non-optionally. + +* If a security fix needs lockstep firmware and kernel fixes in order to + be successful, then all supported major versions in the linux-firmware + repo should be updated with the security fix, and the kernel patches + should detect if the firmware is new enough to declare if the security + issue is fixed. All communications around security fixes should point + at both the firmware and kernel fixes. If a security fix requires + deprecating old major versions, then this should only be done as a + last option, and be stated clearly in all communications. +