[PATCH v2 0/6] mtd: nand: stop DMA before unmapping on error and timeout paths

[Samarth Narang]

This series addresses DMA lifecycle issues in six NAND drivers where
error or timeout paths may unmap buffers before the associated DMA
transfers have stopped. Some paths do not terminate the outstanding
transfers, while others use dmaengine_terminate_all(), which does not
guarantee that the channel has stopped before returning. The patches use
dmaengine_terminate_sync() to ensure that DMA has stopped before
releasing the mappings, and all affected functions already run in a
context where sleeping is permitted.

These issues were identified by a research static analyzer for DMA
lifecycle ordering and have not been validated on hardware. The patches
have only been compile-tested on arm64 with W=1.

Changes in v2:
- Combined the previously submitted patches into a single series, as
  requested by Miquel, and included three additional drivers with
  similar issues (omap2, marvell, and sh_flctl).
- Removed the code comment from the gpmi patch.
- Left qpic_common and stm32_fmc2 unchanged from their earlier
  submissions.

Two questions remain for the qpic_common patch. The BAM driver warns
that resetting a pipe while the attached engine is still active may
cause a fatal error, so it is unclear whether the NAND controller must
be stopped or reset before terminating the DMA channels. The success
path also assumes that completion of the final command descriptor
guarantees completion of the RX data descriptor, which may need
confirmation from the hardware maintainers.

v1:
https://lore.kernel.org/all/20261030143945.2923554-1-samarth.colleges@gmail.com/
https://lore.kernel.org/all/20261030150929.2944717-1-samarth.colleges@gmail.com/
https://lore.kernel.org/all/20261030150646.2942368-1-samarth.colleges@gmail.com/
https://lore.kernel.org/all/20261030151843.2953269-1-samarth.colleges@gmail.com/

Samarth Narang (6):
  mtd: rawnand: gpmi: terminate the DMA chain on completion timeout
  mtd: nand: qpic_common: terminate DMA channels on transfer timeout
  mtd: rawnand: stm32_fmc2: retire data DMA before unmapping on errors
  mtd: rawnand: omap2: terminate DMA when prefetch cannot be enabled
  mtd: rawnand: marvell: stop DMA before unmapping on timeout
  mtd: rawnand: sh_flctl: use dmaengine_terminate_sync() on DMA timeout

 drivers/mtd/nand/qpic_common.c             | 11 +++++++++--
 drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c |  1 +
 drivers/mtd/nand/raw/marvell_nand.c        |  9 +++++----
 drivers/mtd/nand/raw/omap2.c               |  4 +++-
 drivers/mtd/nand/raw/sh_flctl.c            |  2 +-
 drivers/mtd/nand/raw/stm32_fmc2_nand.c     | 13 ++++++++-----
 6 files changed, 27 insertions(+), 13 deletions(-)

base-commit: 24a19b953e2a3d0ea5a8c4951a0ab8f32720c907
-- 
2.34.1