Nouveau - Oct 2025 - [PATCH 0/2] nova-core: remove HWCFG1 and need_riscv

The second patch builds upon the first one. The series applies cleanly
to today's drm-rust-next.

The first patch is identical to what I sent out as a single patch just
now in [1], because I forgot at the time that they should go together as a
tiny patchset.

[1] https://lore.kernel.org/20251025012409.577596-1-jhubbard at nvidia.com

John Hubbard (2):
  nova-core: remove an unnecessary register read: HWCFG1
  nova-core: remove unnecessary need_riscv, bar parameters

 drivers/gpu/nova-core/falcon.rs | 26 +-------------------------
 drivers/gpu/nova-core/gpu.rs    |  4 +---
 2 files changed, 2 insertions(+), 28 deletions(-)


base-commit: d3917368ebc5cd89d7d08eab4673e5c4c73ff42f
-- 
2.51.1

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 at nvidia.com>
---
 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() {
-- 
2.51.1

The need_riscv parameter and its associated RISCV validation logic are
are actually unnecessary for correct operation. Remove it, along with
the now-unused bar parameter as well.

Signed-off-by: John Hubbard <jhubbard at nvidia.com>
---
 drivers/gpu/nova-core/falcon.rs | 21 +--------------------
 drivers/gpu/nova-core/gpu.rs    |  4 +---
 2 files changed, 2 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index ac55cbc5ac1e..d745afacfc40 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -362,26 +362,7 @@ pub(crate) struct Falcon<E: FalconEngine> {
 
 impl<E: FalconEngine + 'static> Falcon<E> {
     /// Create a new falcon instance.
-    ///
-    /// `need_riscv` is set to `true` if the caller expects the falcon to be a
dual falcon/riscv
-    /// controller.
-    pub(crate) fn new(
-        dev: &device::Device,
-        chipset: Chipset,
-        bar: &Bar0,
-        need_riscv: bool,
-    ) -> Result<Self> {
-        if need_riscv {
-            let hwcfg2 = regs::NV_PFALCON_FALCON_HWCFG2::read(bar, &E::ID);
-            if !hwcfg2.riscv() {
-                dev_err!(
-                    dev,
-                    "riscv support requested on a controller that does not
support it\n"
-                );
-                return Err(EINVAL);
-            }
-        }
-
+    pub(crate) fn new(dev: &device::Device, chipset: Chipset) ->
Result<Self> {
         Ok(Self {
             hal: hal::falcon_hal(chipset)?,
             dev: dev.into(),
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index af20e2daea24..9d182bffe8b4 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -213,12 +213,10 @@ pub(crate) fn new<'a>(
             gsp_falcon: Falcon::new(
                 pdev.as_ref(),
                 spec.chipset,
-                bar,
-                spec.chipset > Chipset::GA100,
             )
             .inspect(|falcon| falcon.clear_swgen0_intr(bar))?,
 
-            sec2_falcon: Falcon::new(pdev.as_ref(), spec.chipset, bar, true)?,
+            sec2_falcon: Falcon::new(pdev.as_ref(), spec.chipset)?,
 
             gsp <- Gsp::new(),
 
-- 
2.51.1

On Sat Oct 25, 2025 at 10:40 AM JST, John Hubbard wrote:
> The second patch builds upon the first one. The series applies cleanly
> to today's drm-rust-next.
>
> The first patch is identical to what I sent out as a single patch just
> now in [1], because I forgot at the time that they should go together as a
> tiny patchset.
>
> [1] https://lore.kernel.org/20251025012409.577596-1-jhubbard at nvidia.com
Thanks! This is pretty uncontroversial, so planning to merge this
quickly.

On 10/25/25 3:40 AM, John Hubbard wrote:
> John Hubbard (2):
>   nova-core: remove an unnecessary register read: HWCFG1
>   nova-core: remove unnecessary need_riscv, bar parameters
Acked-by: Danilo Krummrich <dakr at kernel.org>