Merge pull request #20214 from benpicco/CONFIG_SPI_DMA_THRESHOLD_BYTES

cpu/stm32/periph_spi: only perform DMA transfer above threshold
RIOT-OS · Jan 4, 2024 · 7fef2e4 · 7fef2e4
2 parents 616b48d + 753fae6
commit 7fef2e4
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Showing 3 changed files with 9 additions and 9 deletions.
diff --git a/cpu/sam0_common/periph/spi.c b/cpu/sam0_common/periph/spi.c
@@ -38,14 +38,6 @@
 #define ENABLE_DEBUG 0
 #include "debug.h"
 
-/**
- * @brief   Threshold under which polling transfers are used instead of DMA
- *          TODO: determine at run-time based on SPI clock
- */
-#ifndef CONFIG_SPI_DMA_THRESHOLD_BYTES
-#define CONFIG_SPI_DMA_THRESHOLD_BYTES  16
-#endif
-
 /**
  * @brief Array holding one pre-initialized mutex for each SPI device
  */

diff --git a/cpu/stm32/periph/spi.c b/cpu/stm32/periph/spi.c
@@ -390,7 +390,7 @@ void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
     }
 
 #ifdef MODULE_PERIPH_DMA
-    if (_use_dma(&spi_config[bus])) {
+    if (_use_dma(&spi_config[bus]) && len > CONFIG_SPI_DMA_THRESHOLD_BYTES) {
         _transfer_dma(bus, out, in, len);
     }
     else {

diff --git a/drivers/include/periph/spi.h b/drivers/include/periph/spi.h
@@ -80,6 +80,14 @@
 extern "C" {
 #endif
 
+/**
+ * @brief   Threshold under which polling transfers are used instead of DMA
+ *          TODO: determine at run-time based on SPI clock
+ */
+#ifndef CONFIG_SPI_DMA_THRESHOLD_BYTES
+#define CONFIG_SPI_DMA_THRESHOLD_BYTES  16
+#endif
+
 /**
  * @brief   Default SPI device access macro
  */