diff options
| author | Mark Brown <broonie@kernel.org> | 2025-04-30 23:33:59 +0900 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2025-04-30 23:33:59 +0900 |
| commit | a7f035c2c72496cf7ac34bfaa8c289e0d4c45836 (patch) | |
| tree | 1962110083a27f50a6b0f08d44e6f225e6bd7cbd /rust/kernel | |
| parent | df8c5ad0f56635341bfe3f59ef7c6473e389abc4 (diff) | |
| parent | e6702c44c2adb28b62f81de498e9b1e4562ce660 (diff) | |
spi: axi-spi-engine: offload instruction optimization
Merge series from David Lechner <dlechner@baylibre.com>:
In order to achieve a 4 MSPS rate on a 16-bit ADC with a 80 MHz SCLK
using the SPI offload feature of the AXI SPI Engine, we need to shave
off some time that is spent executing unnecessary instructions. There
are a few one-time setup instructions that can be moved so that they
execute only once when the SPI offload trigger is enabled rather than
repeating each time the offload is triggered. Additionally, a recent
change to the IP block allows dropping the SYNC instruction completely.
With these changes, we are left with only the 3 instructions that are
needed to to assert CS, transfer the data, and deassert CS. This makes
3 + 16 * 12.5 ns = 237.5 ns < 250 ns which is comfortably within the
available time period.
Diffstat (limited to 'rust/kernel')
| -rw-r--r-- | rust/kernel/firmware.rs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index f04b058b09b2..2494c96e105f 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -4,7 +4,7 @@ //! //! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h) -use crate::{bindings, device::Device, error::Error, error::Result, str::CStr}; +use crate::{bindings, device::Device, error::Error, error::Result, ffi, str::CStr}; use core::ptr::NonNull; /// # Invariants @@ -12,7 +12,11 @@ use core::ptr::NonNull; /// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`, /// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`. struct FwFunc( - unsafe extern "C" fn(*mut *const bindings::firmware, *const u8, *mut bindings::device) -> i32, + unsafe extern "C" fn( + *mut *const bindings::firmware, + *const ffi::c_char, + *mut bindings::device, + ) -> i32, ); impl FwFunc { |