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Diffstat (limited to 'drivers/gpu/nova-core/fb.rs')
| -rw-r--r-- | drivers/gpu/nova-core/fb.rs | 10 |
1 files changed, 10 insertions, 0 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 { |