diff options
| -rw-r--r-- | drivers/gpu/nova-core/fb.rs | 10 | ||||
| -rw-r--r-- | drivers/gpu/nova-core/gpu.rs | 3 | ||||
| -rw-r--r-- | drivers/gpu/nova-core/regs.rs | 3 |
3 files changed, 14 insertions, 2 deletions
diff --git a/drivers/gpu/nova-core/fb.rs b/drivers/gpu/nova-core/fb.rs index 172b4a12ba2a..4a702525fff4 100644 --- a/drivers/gpu/nova-core/fb.rs +++ b/drivers/gpu/nova-core/fb.rs @@ -17,6 +17,16 @@ mod hal; /// Type holding the sysmem flush memory page, a page of memory to be written into the /// `NV_PFB_NISO_FLUSH_SYSMEM_ADDR*` registers and used to maintain memory coherency. /// +/// A system memory page is required for `sysmembar`, which is a GPU-initiated hardware +/// memory-barrier operation that flushes all pending GPU-side memory writes that were done through +/// PCIE to system memory. It is required for falcons to be reset as the reset operation involves a +/// reset handshake. When the falcon acknowledges a reset, it writes into system memory. To ensure +/// this write is visible to the host and prevent driver timeouts, the falcon must perform a +/// sysmembar operation to flush its writes. +/// +/// Because of this, the sysmem flush memory page must be registered as early as possible during +/// driver initialization, and before any falcon is reset. +/// /// Users are responsible for manually calling [`Self::unregister`] before dropping this object, /// otherwise the GPU might still use it even after it has been freed. pub(crate) struct SysmemFlush { diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs index 8e32af16b669..72d40b0124f0 100644 --- a/drivers/gpu/nova-core/gpu.rs +++ b/drivers/gpu/nova-core/gpu.rs @@ -170,7 +170,7 @@ pub(crate) struct Gpu { bar: Devres<Bar0>, fw: Firmware, /// System memory page required for flushing all pending GPU-side memory writes done through - /// PCIE into system memory. + /// PCIE into system memory, via sysmembar (A GPU-initiated HW memory-barrier operation). sysmem_flush: SysmemFlush, } @@ -283,7 +283,6 @@ impl Gpu { gfw::wait_gfw_boot_completion(bar) .inspect_err(|_| dev_err!(pdev.as_ref(), "GFW boot did not complete"))?; - // System memory page required for sysmembar to properly flush into system memory. let sysmem_flush = SysmemFlush::register(pdev.as_ref(), bar, spec.chipset)?; let gsp_falcon = Falcon::<Gsp>::new( diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs index 3bb38197a890..317da64afa91 100644 --- a/drivers/gpu/nova-core/regs.rs +++ b/drivers/gpu/nova-core/regs.rs @@ -51,6 +51,9 @@ register!(NV_PBUS_SW_SCRATCH_0E@0x00001438 { /* PFB */ +// The following two registers together hold the physical system memory address that is used by the +// GPU to perform sysmembar operations (see `fb::SysmemFlush`). + register!(NV_PFB_NISO_FLUSH_SYSMEM_ADDR @ 0x00100c10 { 31:0 adr_39_08 as u32; }); |