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Date: Tue, 13 May 2025 16:47:57 +0200
From: Danilo Krummrich <dakr@kernel.org>
To: Alexandre Courbot <acourbot@nvidia.com>
Cc: Miguel Ojeda <ojeda@kernel.org>, Alex Gaynor <alex.gaynor@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <benno.lossin@proton.me>,
	Andreas Hindborg <a.hindborg@kernel.org>,
	Alice Ryhl <aliceryhl@google.com>, Trevor Gross <tmgross@umich.edu>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Jonathan Corbet <corbet@lwn.net>,
	John Hubbard <jhubbard@nvidia.com>, Ben Skeggs <bskeggs@nvidia.com>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Timur Tabi <ttabi@nvidia.com>, Alistair Popple <apopple@nvidia.com>,
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
	nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v3 11/19] gpu: nova-core: register sysmem flush page
Message-ID: <aCNbnWJKM_O8sLtP@pollux>
References: <20250507-nova-frts-v3-0-fcb02749754d@nvidia.com>
 <20250507-nova-frts-v3-11-fcb02749754d@nvidia.com>
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In-Reply-To: <20250507-nova-frts-v3-11-fcb02749754d@nvidia.com>

On Wed, May 07, 2025 at 10:52:38PM +0900, Alexandre Courbot wrote:
> A page of system memory is reserved so sysmembar can perform a read on

NIT: Use imperative mood.

> it if a system write occurred since the last flush. Do this early as it
> can be required to e.g. reset the GPU falcons.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  drivers/gpu/nova-core/gpu.rs  | 45 +++++++++++++++++++++++++++++++++++++++++--
>  drivers/gpu/nova-core/regs.rs | 10 ++++++++++
>  2 files changed, 53 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> index a9fcf74717791dc7e23678869bf84f61e51873e2..c338da69ecbc2200f1ef3061a4d62971b021e3eb 100644
> --- a/drivers/gpu/nova-core/gpu.rs
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -3,6 +3,7 @@
>  use kernel::{device, devres::Devres, error::code::*, pci, prelude::*};
>  
>  use crate::devinit;
> +use crate::dma::DmaObject;
>  use crate::driver::Bar0;
>  use crate::firmware::Firmware;
>  use crate::regs;
> @@ -158,12 +159,32 @@ fn new(bar: &Bar0) -> Result<Spec> {
>  }
>  
>  /// Structure holding the resources required to operate the GPU.
> -#[pin_data]
> +#[pin_data(PinnedDrop)]
>  pub(crate) struct Gpu {
>      spec: Spec,
>      /// MMIO mapping of PCI BAR 0
>      bar: Devres<Bar0>,
>      fw: Firmware,
> +    // System memory page required for flushing all pending GPU-side memory writes done through
> +    // PCIE into system memory.

Please make this a doc-comment.