Russell King - ARM Linux wrote:
Sent: Wednesday, March 07, 2012 7:35 AM
To: Dan Williams; Vinod Koul
Cc: Stephen Warren; Linus Walleij; Srinidhi Kasagar; Li Yang;
linuxppc-dev@lists.ozlabs.org;
linux-arm-ker...@lists.infradead.org
Subject: [PATCH 5/9] dmaengine: provide a common function for completing a
dma descriptor
Provide a common function to do the cookie mechanics for completing
a DMA descriptor.
Dear Russell,
I met a problem on DMA cyclic mode (DMA_CYCLIC) for sound playback.
Kernel BUG occurs during DMA transfer with DMA cyclic mode.
This patch makes the cookies into zero. But, cookies should be kept during
cyclic mode
because cyclic mode re-uses the cookies.
So, Error occurs on BUG_ON(tx-cookie DMA_MIN_COOKIE) lines on
dma_cookie_complete().
Please see following error.
[ cut here ]
kernel BUG at drivers/dma/dmaengine.h:53!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0Tainted: GW (3.4.0-rc2-00596-gc7d7a63 #5)
PC is at pl330_tasklet+0x58c/0x59c
LR is at _raw_spin_lock_irqsave+0x10/0x14
pc : [c0238a84]lr : [c052a3f4]psr: 68000193
sp : c06efde0 ip : fp : c06efe4c
r10: r9 : r8 : c06efe18
r7 : d881b414 r6 : d881b410 r5 : d881b450 r4 : 0003
r3 : d8814bcc r2 : d8814b60 r1 : r0 : d8814b60
Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 10c5387d Table: 57eb806a DAC: 0015
I think the completing a dma descriptor without setting zero to cookies is
required for cyclic mode.
Do I make new macro or modify dma_cookie_complete() for it?
Thanks
Boojin.
Signed-off-by: Russell King rmk+ker...@arm.linux.org.uk
---
drivers/dma/amba-pl08x.c|2 +-
drivers/dma/at_hdmac.c |2 +-
drivers/dma/coh901318.c |2 +-
drivers/dma/dmaengine.h | 18 ++
drivers/dma/dw_dmac.c |2 +-
drivers/dma/ep93xx_dma.c|2 +-
drivers/dma/fsldma.c|2 +-
drivers/dma/imx-dma.c |2 +-
drivers/dma/imx-sdma.c |2 +-
drivers/dma/intel_mid_dma.c |2 +-
drivers/dma/ioat/dma.c |3 +--
drivers/dma/ioat/dma_v2.c |3 +--
drivers/dma/ioat/dma_v3.c |3 +--
drivers/dma/ipu/ipu_idmac.c |2 +-
drivers/dma/mxs-dma.c |2 +-
drivers/dma/pl330.c |2 +-
drivers/dma/ste_dma40.c |2 +-
drivers/dma/timb_dma.c |2 +-
drivers/dma/txx9dmac.c |2 +-
19 files changed, 36 insertions(+), 21 deletions(-)
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 5996386..f0888c1 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -1540,7 +1540,7 @@ static void pl08x_tasklet(unsigned long data)
if (txd) {
/* Update last completed */
- plchan-chan.completed_cookie = txd-tx.cookie;
+ dma_cookie_complete(txd-tx);
}
/* If a new descriptor is queued, set it up plchan-at is NULL here */
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index df47e7d..b282630 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -249,7 +249,7 @@ atc_chain_complete(struct at_dma_chan *atchan, struct
at_desc *desc)
dev_vdbg(chan2dev(atchan-chan_common),
descriptor %u complete\n, txd-cookie);
- atchan-chan_common.completed_cookie = txd-cookie;
+ dma_cookie_complete(txd);
/* move children to free_list */
list_splice_init(desc-tx_list, atchan-free_list);
diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
index 843a1a3..24837d7 100644
--- a/drivers/dma/coh901318.c
+++ b/drivers/dma/coh901318.c
@@ -691,7 +691,7 @@ static void dma_tasklet(unsigned long data)
callback_param = cohd_fin-desc.callback_param;
/* sign this job as completed on the channel */
- cohc-chan.completed_cookie = cohd_fin-desc.cookie;
+ dma_cookie_complete(cohd_fin-desc);
/* release the lli allocation and remove the descriptor */
coh901318_lli_free(cohc-base-pool, cohd_fin-lli);
diff --git a/drivers/dma/dmaengine.h b/drivers/dma/dmaengine.h
index 7692c86..47e0997 100644
--- a/drivers/dma/dmaengine.h
+++ b/drivers/dma/dmaengine.h
@@ -5,6 +5,7 @@
#ifndef DMAENGINE_H
#define DMAENGINE_H
+#include linux/bug.h
#include linux/dmaengine.h
/**
@@ -27,4 +28,21 @@ static inline dma_cookie_t dma_cookie_assign(struct
dma_async_tx_descriptor
*tx)
return cookie;
}
+/**
+ * dma_cookie_complete - complete a descriptor
+ * @tx: descriptor to complete
+ *
+ * Mark this descriptor complete by updating the channels completed
+ * cookie marker. Zero the descriptors cookie to prevent accidental
+ * repeated completions.
+ *
+ * Note: caller is expected to hold a lock to prevent concurrency.
+ */
+static inline void dma_cookie_complete(struct dma_async_tx_descriptor *tx)
+{
+ BUG_ON(tx-cookie DMA_MIN_COOKIE);
