dmaengine: ste_dma40: Return IRQ_NONE when no interrupt is pending

d40_handle_interrupt() returns IRQ_HANDLED even when no terminal-count or
error status bit is pending.

IRQ_NONE is not only used to identify a device on a shared interrupt.
The generic IRQ core also counts it as unhandled for spurious IRQ
detection. DMA40 does not request this IRQ with IRQF_SHARED, so interrupt
sharing is not the purpose of this change.

If the line remains asserted without matching DMA40 status, returning
IRQ_HANDLED hides the stuck interrupt and can leave the CPU servicing it
indefinitely. Track whether any DMA40 status is pending and return IRQ_NONE
when none is present, allowing the generic IRQ core to diagnose and
eventually disable the faulty line.

DMA40 channels can be owned by other SoC cores. Their status means that
the interrupt is real, but Linux must not acknowledge it. Treat foreign
status as handled and leave its acknowledgment to the owning core, while
acknowledging and dispatching only registered Linux channels.

Fixes: 8d318a50b3d7 ("DMAENGINE: Support for ST-Ericssons DMA40 block v3")
Assisted-by: LLM
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260927-dma40-fixes-v7-8-89f595e8851d@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

0 files changed, 0 insertions, 0 deletions