From patchwork Wed Mar 5 22:59:33 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 14003644 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 0723EC19F32 for ; Wed, 5 Mar 2025 23:07:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 509E610E84F; Wed, 5 Mar 2025 23:07:03 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="iGSgPfUP"; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id B4E7410E84F for ; Wed, 5 Mar 2025 23:07:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741216021; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iGhdforG/hfsTGcf1d8lWIscR/N9faUXID3wN0fe8hE=; b=iGSgPfUPg3VXLesHXUxyj85lVsp/ED/Ll+pzlw+k25uzpVhc4Qlxw9cqWwkvAvIYKOi9Rv 5GWXhDHHu02nPL9i6rmlNTzzZX2zaXUeJ4bXBI3vxU8RCoiZygqJIuiMje4WA0LVAbGT0x Ke9HIka80GKsHXOfQxTIHsz+qXlE0FE= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-391-7XKPghc_PD-C1h_03dlyvw-1; Wed, 05 Mar 2025 18:06:58 -0500 X-MC-Unique: 7XKPghc_PD-C1h_03dlyvw-1 X-Mimecast-MFC-AGG-ID: 7XKPghc_PD-C1h_03dlyvw_1741216016 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6ED5F180025A; Wed, 5 Mar 2025 23:06:56 +0000 (UTC) Received: from chopper.redhat.com (unknown [10.22.88.81]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 57C33300019E; Wed, 5 Mar 2025 23:06:53 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org Cc: Danilo Krummrich , mcanal@igalia.com, Alice Ryhl , Maxime Ripard , Simona Vetter , Daniel Almeida , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?B?= =?utf-8?q?j=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-kernel@vger.kernel.org (open list) Subject: [RFC v3 17/33] rust: drm/kms: Add OpaqueEncoder Date: Wed, 5 Mar 2025 17:59:33 -0500 Message-ID: <20250305230406.567126-18-lyude@redhat.com> In-Reply-To: <20250305230406.567126-1-lyude@redhat.com> References: <20250305230406.567126-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Same thing as OpaquePlane, but for encoders now. Signed-off-by: Lyude Paul --- V3: * Add safety comment to ModeObject implementation * Add safety comments for AsRawEncoder * Implement try_from_opaque() and from_opaque() using a macro Signed-off-by: Lyude Paul --- rust/kernel/drm/kms/encoder.rs | 91 +++++++++++++++++++++++++++++++++- 1 file changed, 90 insertions(+), 1 deletion(-) diff --git a/rust/kernel/drm/kms/encoder.rs b/rust/kernel/drm/kms/encoder.rs index 2e4e88055c890..9ae2ff8eb5d50 100644 --- a/rust/kernel/drm/kms/encoder.rs +++ b/rust/kernel/drm/kms/encoder.rs @@ -4,7 +4,7 @@ //! //! C header: [`include/drm/drm_encoder.h`](srctree/include/drm/drm_encoder.h) -use super::{KmsDriver, ModeObject, StaticModeObject, UnregisteredKmsDevice}; +use super::{KmsDriver, ModeObject, ModeObjectVtable, StaticModeObject, UnregisteredKmsDevice}; use crate::{ alloc::KBox, drm::device::Device, @@ -219,6 +219,25 @@ unsafe fn from_raw<'a>(ptr: *mut bindings::drm_encoder) -> &'a Self { } } +// SAFETY: `funcs` is initialized when the encoder is allocated +unsafe impl ModeObjectVtable for Encoder { + type Vtable = bindings::drm_encoder_funcs; + + fn vtable(&self) -> *const Self::Vtable { + // SAFETY: `as_raw()` always returns a valid pointer to an encoder + unsafe { *self.as_raw() }.funcs + } +} + +impl Encoder { + super::impl_from_opaque_mode_obj! { + fn <'a, D>(&'a OpaqueEncoder) -> &'a Self; + use + T as DriverEncoder, + D as KmsDriver + } +} + /// A [`Encoder`] that has not yet been registered with userspace. /// /// KMS registration is single-threaded, so this object is not thread-safe. @@ -311,6 +330,76 @@ pub fn new<'a, 'b: 'a>( } } +/// A [`struct drm_encoder`] without a known [`DriverEncoder`] implementation. +/// +/// This is mainly for situations where our bindings can't infer the [`DriverEncoder`] implementation +/// for a [`struct drm_encoder`] automatically. It is identical to [`Encoder`], except that it does not +/// provide access to the driver's private data. +/// +/// # Invariants +/// +/// Same as [`Encoder`]. +#[repr(transparent)] +pub struct OpaqueEncoder { + encoder: Opaque, + _p: PhantomData, +} + +impl Sealed for OpaqueEncoder {} + +// SAFETY: All of our encoder interfaces are thread-safe +unsafe impl Send for OpaqueEncoder {} + +// SAFETY: All of our encoder interfaces are thread-safe +unsafe impl Sync for OpaqueEncoder {} + +// SAFETY: We don't expose OpaqueEncoder to users before `base` is initialized in +// OpaqueEncoder::new(), so `raw_mode_obj` always returns a valid poiner to a +// bindings::drm_mode_object. +unsafe impl ModeObject for OpaqueEncoder { + type Driver = T; + + fn drm_dev(&self) -> &Device { + // SAFETY: DRM encoders exist for as long as the device does, so this pointer is always + // valid + unsafe { Device::borrow((*self.encoder.get()).dev) } + } + + fn raw_mode_obj(&self) -> *mut bindings::drm_mode_object { + // SAFETY: We don't expose Encoder to users before it's initialized, so `base` is always + // initialized + unsafe { addr_of_mut!((*self.encoder.get()).base) } + } +} + +// SAFETY: Encoders do not have a refcount +unsafe impl StaticModeObject for OpaqueEncoder {} + +// SAFETY: +// - Via our type variants our data layout is identical to with `drm_encoder` +// - Since we don't expose `Encoder` to users before it has been initialized, this and our data +// layout ensure that `as_raw()` always returns a valid pointer to a `drm_encoder`. +unsafe impl AsRawEncoder for OpaqueEncoder { + fn as_raw(&self) -> *mut bindings::drm_encoder { + self.encoder.get() + } + + unsafe fn from_raw<'a>(ptr: *mut bindings::drm_encoder) -> &'a Self { + // SAFETY: Our data layout is identical to `bindings::drm_encoder` + unsafe { &*ptr.cast() } + } +} + +// SAFETY: `funcs` is initialized when the encoder is allocated +unsafe impl ModeObjectVtable for OpaqueEncoder { + type Vtable = bindings::drm_encoder_funcs; + + fn vtable(&self) -> *const Self::Vtable { + // SAFETY: `as_raw()` always returns a valid pointer to an encoder + unsafe { *self.as_raw() }.funcs + } +} + unsafe extern "C" fn encoder_destroy_callback( encoder: *mut bindings::drm_encoder, ) {