Cache invalidation issues around DMA accesses can be difficult to debug. Motivated by recent fixes to the macb driver[1], let's add some optional sanity checking to the DMA API inspired by the Linux CONFIG_DMA_API_DEBUG option. This would have caught the issue fixed by [1] in the macb driver and it already caught a misuse of the API on the STM32MP system I tested it on. Usage is simple: just enable it and ensure no warnings are printed. All warnings are printed alongside the extents of the DMA buffer in question and a stack trace at the time the check failed. [1]: https://lore.barebox.org/barebox/20231128-v2023-08-0-topic-macb-v1-0-9faff73bc990@xxxxxxxxxxxxxx/T/#t Ahmad Fatoum (4): dma: factor out dma map generic implementations into file dma: add DMA API debugging support mci: core: remove broken, unneeded write bounce buffer mci: stm32_sdmmc2: correct usage of DMA API common/Kconfig | 14 +++ drivers/dma/Makefile | 2 + drivers/dma/debug.c | 183 +++++++++++++++++++++++++++++++++++++ drivers/dma/debug.h | 56 ++++++++++++ drivers/dma/map.c | 43 +++++++++ drivers/mci/mci-core.c | 10 +- drivers/mci/stm32_sdmmc2.c | 41 +++++---- include/dma.h | 61 ++++--------- 8 files changed, 340 insertions(+), 70 deletions(-) create mode 100644 drivers/dma/debug.c create mode 100644 drivers/dma/debug.h create mode 100644 drivers/dma/map.c -- 2.39.2
