dma: add DMA API debugging support

For DMA_FROM_DEVICE, calling dma_sync_single_for_cpu
before arch_sync_dma_for_device has been called is wrong:

  - Memory region is dirty in CPU cache
  - Device writes packet into region
  - CPU cache lines are written back
  - Buffer memory is corrupted

In order to spot such issues, let's add a new CONFIG_DMA_API_DEBUG
that will warn about mismatch in order.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20231129061758.1781732-3-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/common/Kconfig b/common/Kconfig
index 76b28ceaaf..c423f37677 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -1685,6 +1685,20 @@ config DEBUG_PROBES
 	  Most consoles do not implement a remove callback to remain operable until
 	  the very end. Consoles using DMA, however, must be removed.
 
+config DMA_API_DEBUG
+	bool "Enable debugging of DMA-API usage"
+	depends on HAS_DMA
+	help
+	  Enable this option to debug the use of the DMA API by device drivers.
+	  With this option you will be able to detect common bugs in device
+	  drivers like double-freeing of DMA mappings or freeing mappings that
+	  were never allocated.
+
+	  This option causes a performance degradation.  Use only if you want to
+	  debug device drivers and dma interactions.
+
+	  If unsure, say N.
+
 config PBL_BREAK
 	bool "Execute software break on pbl start"
 	depends on ARM && (!CPU_32v4T && !ARCH_TEGRA)