[PATCH 4.19 01/74] ARM: riscpc: fix DMA

Greg Kroah-Hartman
2019-08-05T13:09:03Z

[ Upstream commit ffd9a1ba9fdb7f2bd1d1ad9b9243d34e96756ba2 ]

DMA got broken a while back in two different ways:
1) a change in the behaviour of disable_irq() to wait for the interrupt
to finish executing causes us to deadlock at the end of DMA.
2) a change to avoid modifying the scatterlist left the first transfer
uninitialised.

DMA is only used with expansion cards, so has gone unnoticed.

Fixes: fa4e99899932 ("[ARM] dma: RiscPC: don't modify DMA SG entries")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/mach-rpc/dma.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-rpc/dma.c b/arch/arm/mach-rpc/dma.c
index fb48f3141fb4d..c4c96661eb89a 100644
--- a/arch/arm/mach-rpc/dma.c
+++ b/arch/arm/mach-rpc/dma.c
@@ -131,7 +131,7 @@ static irqreturn_t iomd_dma_handle(int irq, void *dev_id)
} while (1);

idma->state = ~DMA_ST_AB;
- disable_irq(irq);
+ disable_irq_nosync(irq);

return IRQ_HANDLED;
}
@@ -174,6 +174,9 @@ static void iomd_enable_dma(unsigned int chan, dma_t *dma)
DMA_FROM_DEVICE : DMA_TO_DEVICE);
}

+ idma->dma_addr = idma->dma.sg->dma_address;
+ idma->dma_len = idma->dma.sg->length;
+
iomd_writeb(DMA_CR_C, dma_base + CR);
idma->state = DMA_ST_AB;
}
--
2.20.1