linux-kernel - [PATCH] nova-core: remove an unnecessary register read: HWCFG1

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Message-ID: <20251025012409.577596-1-jhubbard@nvidia.com>
Date: Fri, 24 Oct 2025 18:24:08 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: Alexandre Courbot <acourbot@...dia.com>,
	Joel Fernandes <joelagnelf@...dia.com>,
	Timur Tabi <ttabi@...dia.com>,
	Alistair Popple <apopple@...dia.com>,
	Edwin Peer <epeer@...dia.com>,
	Zhi Wang <zhiw@...dia.com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	nouveau@...ts.freedesktop.org,
	rust-for-linux@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	John Hubbard <jhubbard@...dia.com>
Subject: [PATCH] nova-core: remove an unnecessary register read: HWCFG1

This register read is not required in order to bring up any of the GPUs,
and it is read too early on Hopper/Blackwell+ GPUs anyway. So just stop
doing this.

Signed-off-by: John Hubbard <jhubbard@...dia.com>
---

This applies cleanly to today's drm-rust-next.

thanks,
John Hubbard


 drivers/gpu/nova-core/falcon.rs | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index 3f505b870601..ac55cbc5ac1e 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -371,11 +371,6 @@ pub(crate) fn new(
         bar: &Bar0,
         need_riscv: bool,
     ) -> Result<Self> {
-        let hwcfg1 = regs::NV_PFALCON_FALCON_HWCFG1::read(bar, &E::ID);
-        // Check that the revision and security model contain valid values.
-        let _ = hwcfg1.core_rev()?;
-        let _ = hwcfg1.security_model()?;
-
         if need_riscv {
             let hwcfg2 = regs::NV_PFALCON_FALCON_HWCFG2::read(bar, &E::ID);
             if !hwcfg2.riscv() {

base-commit: d3917368ebc5cd89d7d08eab4673e5c4c73ff42f
-- 
2.51.1