From patchwork Wed Mar 5 22:59:35 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 14003646 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 BA3F0C282EC for ; Wed, 5 Mar 2025 23:07:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2F43010E854; Wed, 5 Mar 2025 23:07:41 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="eYdGplTg"; 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 1B62010E854 for ; Wed, 5 Mar 2025 23:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741216059; 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=j/D4SEgwMMDnFfsGfNIexwP9lfVhLyJ7Nk/oo5mITW4=; b=eYdGplTg6VVMWYu4/qadzNpfzBtnnkWh6673giK8nw4hHWhoonEEYWOlVZxnn6gqfLK8FN Ich45VxPD2IaBARVEkSYU4gzmZ/l/ch+c+iJR71hnm7x5teLuqvF74ac2KESHjst3SEOG3 QQalCwVW9YX1go5civRLTdca3NPYEtM= 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-251-oPRhXijONZ-enFPmMxsMWA-1; Wed, 05 Mar 2025 18:07:29 -0500 X-MC-Unique: oPRhXijONZ-enFPmMxsMWA-1 X-Mimecast-MFC-AGG-ID: oPRhXijONZ-enFPmMxsMWA_1741216046 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 BB960180025B; Wed, 5 Mar 2025 23:07:26 +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 A13EB30001A1; Wed, 5 Mar 2025 23:07:22 +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 19/33] rust: drm/kms: Add DriverCrtc::atomic_check() Date: Wed, 5 Mar 2025 17:59:35 -0500 Message-ID: <20250305230406.567126-20-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" An optional trait method for implementing a CRTC's atomic state check. Signed-off-by: Lyude Paul --- V3: * Document uses of ManuallyDrop Signed-off-by: Lyude Paul --- rust/kernel/drm/kms/atomic.rs | 1 - rust/kernel/drm/kms/crtc.rs | 55 +++++++++++++++++++++++++++++++++-- 2 files changed, 52 insertions(+), 4 deletions(-) diff --git a/rust/kernel/drm/kms/atomic.rs b/rust/kernel/drm/kms/atomic.rs index 3d5c70dbc4274..e0a1b5b860d6f 100644 --- a/rust/kernel/drm/kms/atomic.rs +++ b/rust/kernel/drm/kms/atomic.rs @@ -274,7 +274,6 @@ impl AtomicStateComposer { /// # Safety /// /// The caller guarantees that `ptr` points to a valid instance of `drm_atomic_state`. - #[allow(dead_code)] pub(crate) unsafe fn new(ptr: NonNull) -> Self { // SAFETY: see `AtomicStateMutator::from_raw()` Self(unsafe { AtomicStateMutator::new(ptr) }) diff --git a/rust/kernel/drm/kms/crtc.rs b/rust/kernel/drm/kms/crtc.rs index 3b9c9d97fcf24..50f5b68f4a3fe 100644 --- a/rust/kernel/drm/kms/crtc.rs +++ b/rust/kernel/drm/kms/crtc.rs @@ -12,7 +12,7 @@ alloc::KBox, bindings, drm::device::Device, - error::to_result, + error::{from_result, to_result}, init::Zeroable, prelude::*, private::Sealed, @@ -21,7 +21,7 @@ use core::{ cell::{Cell, UnsafeCell}, marker::*, - mem, + mem::{self, ManuallyDrop}, ops::{Deref, DerefMut}, ptr::{addr_of_mut, null, null_mut, NonNull}, }; @@ -78,7 +78,11 @@ pub trait DriverCrtc: Send + Sync + Sized { helper_funcs: bindings::drm_crtc_helper_funcs { atomic_disable: None, atomic_enable: None, - atomic_check: None, + atomic_check: if Self::HAS_ATOMIC_CHECK { + Some(atomic_check_callback::) + } else { + None + }, dpms: None, commit: None, prepare: None, @@ -113,6 +117,21 @@ pub trait DriverCrtc: Send + Sync + Sized { /// /// Drivers may use this to instantiate their [`DriverCrtc`] object. fn new(device: &Device, args: &Self::Args) -> impl PinInit; + + /// The optional [`drm_crtc_helper_funcs.atomic_check`] hook for this crtc. + /// + /// Drivers may use this to customize the atomic check phase of their [`Crtc`] objects. The + /// result of this function determines whether the atomic check passed or failed. + /// + /// [`drm_crtc_helper_funcs.atomic_check`]: srctree/include/drm/drm_modeset_helper_vtables.h + fn atomic_check( + _crtc: &Crtc, + _old_state: &CrtcState, + _new_state: CrtcStateMutator<'_, CrtcState>, + _state: &AtomicStateComposer, + ) -> Result { + build_error::build_error("This should not be reachable") + } } /// The generated C vtable for a [`DriverCrtc`]. @@ -859,3 +878,33 @@ fn vtable(&self) -> *const Self::Vtable { // SAFETY: DRM takes ownership of the state from here, and will never move it unsafe { bindings::__drm_atomic_helper_crtc_reset(crtc.as_raw(), KBox::into_raw(new).cast()) }; } + +unsafe extern "C" fn atomic_check_callback( + crtc: *mut bindings::drm_crtc, + state: *mut bindings::drm_atomic_state, +) -> i32 { + // SAFETY: + // - We're guaranteed `crtc` is of type `Crtc` via type invariants. + // - We're guaranteed by DRM that `crtc` is pointing to a valid initialized state. + let crtc = unsafe { Crtc::from_raw(crtc) }; + + // SAFETY: DRM guarantees `state` points to a valid `drm_atomic_state` + // We use a ManuallyDrop here to avoid AtomicStateComposer dropping an owned reference we never + // acquired. + let state = + unsafe { ManuallyDrop::new(AtomicStateComposer::new(NonNull::new_unchecked(state))) }; + + // SAFETY: Since we are in the atomic update callback, we're guaranteed by DRM that both the old + // and new atomic state are present within `state` + let (old_state, new_state) = unsafe { + ( + state.get_old_crtc_state(crtc).unwrap_unchecked(), + state.get_new_crtc_state(crtc).unwrap_unchecked(), + ) + }; + + from_result(|| { + T::atomic_check(crtc, old_state, new_state, &state)?; + Ok(0) + }) +}