[PATCH v4 07/17] gpu: nova-core: wait for GFW boot in probe, not in the Gpu constructor

[John Hubbard <jhubbard@nvidia.com>]

The GPU boots its own firmware, GFW, out of reset, and nothing may
program the GPU until GFW reports completion.

nova-core waited for GFW inside the Gpu constructor, which also boots
the GSP. Code that has to run after GFW and before GSP boot, such as a
probe-time hardware self-test, had nowhere to go.

Move the wait into probe, ahead of the Gpu constructor, and read the
chipset there from a Spec that probe builds itself. Leave the DMA mask
in the constructor, since it programs the host rather than the GPU.

Assisted-by: LLM
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/driver.rs | 13 ++++++++++++-
 drivers/gpu/nova-core/gpu.rs    | 28 ++++++++++++++++++++--------
 2 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 0672a0707a71..15a44f9a6441 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -22,7 +22,13 @@
     types::CovariantForLt,
 };
 
-use crate::gpu::Gpu;
+use crate::{
+    gpu,
+    gpu::{
+        Gpu,
+        Spec, //
+    }, //
+};
 
 /// Counter for generating unique auxiliary device IDs.
 static AUXILIARY_ID_COUNTER: Atomic<u32> = Atomic::new(0);
@@ -109,6 +115,11 @@ fn probe<'bound>(
                     let bar1_idx = bar1_resource_index(pdev)?;
                     pdev.iomap_region(bar1_idx, c"nova-core/bar1")?
                 },
+                _: {
+                    let spec = Spec::new(pdev.as_ref(), bar)?;
+
+                    gpu::wait_gfw_boot_completion(pdev.as_ref(), bar, spec.chipset)?;
+                },
                 // TODO: Use self-referential pin-init syntax once available.
                 gpu <- Gpu::new(
                     pdev,
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index d763bc8d3827..3d796d6c7013 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -212,12 +212,12 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 /// Structure holding a basic description of the GPU: `Chipset` and `Revision`.
 #[derive(Clone, Copy)]
 pub(crate) struct Spec {
-    chipset: Chipset,
+    pub(crate) chipset: Chipset,
     revision: Revision,
 }
 
 impl Spec {
-    fn new(dev: &device::Device, bar: Bar0<'_>) -> Result<Spec> {
+    pub(crate) fn new(dev: &device::Device, bar: Bar0<'_>) -> Result<Spec> {
         // Some brief notes about boot0 and boot42, in chronological order:
         //
         // NV04 through NV50:
@@ -362,17 +362,12 @@ pub(crate) fn new<'a>(
                 dev_info!(dev,"NVIDIA ({})\n", spec);
             })?,
 
-            // We must wait for GFW_BOOT completion before doing any significant setup on the GPU.
             _: {
-                let hal = hal::gpu_hal(spec.chipset);
-                let dma_mask = hal.dma_mask();
+                let dma_mask = hal::gpu_hal(spec.chipset).dma_mask();
 
                 // SAFETY: `Gpu` owns all DMA allocations for this device, and we are
                 // still constructing it, so no concurrent DMA allocations can exist.
                 unsafe { pdev.dma_set_mask_and_coherent(dma_mask)? };
-
-                hal.wait_gfw_boot_completion(bar)
-                    .inspect_err(|_| dev_err!(dev, "GFW boot did not complete\n"))?;
             },
 
             // Initialize this early because `gsp_resources` depends on it.
@@ -495,6 +490,23 @@ pub(crate) fn run_selftests(self: Pin<&mut Self>, pdev: &pci::Device<device::Bou
     }
 }
 
+/// Waits for GFW, the GPU's boot firmware, to report completion.
+///
+/// Nothing may program the GPU before then.
+///
+/// # Errors
+///
+/// `ETIMEDOUT` if GFW does not report completion in time.
+pub(crate) fn wait_gfw_boot_completion(
+    dev: &device::Device<device::Bound>,
+    bar: Bar0<'_>,
+    chipset: Chipset,
+) -> Result {
+    hal::gpu_hal(chipset)
+        .wait_gfw_boot_completion(bar)
+        .inspect_err(|_| dev_err!(dev, "GFW boot did not complete\n"))
+}
+
 /// Reads the boot0 register and returns its raw value.
 pub(crate) fn boot_0_raw(bar: Bar0<'_>) -> u32 {
     bar.read(regs::NV_PMC_BOOT_0).into_raw()
-- 
2.55.0