This is a note to let you know that I've just added the patch titled
dmaengine: dw: don't perform DMA when dmaengine_submit is called
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dmaengine-dw-don-t-perform-dma-when-dmaengine_submit-is-called.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dd8ecfcac66b4485416b2d1df0ec4798b198d7d6 Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Date: Wed, 18 Jun 2014 12:15:38 +0300
Subject: dmaengine: dw: don't perform DMA when dmaengine_submit is called
From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
commit dd8ecfcac66b4485416b2d1df0ec4798b198d7d6 upstream.
Accordingly to discussion [1] and followed up documentation the DMA controller
driver shouldn't start any DMA operations when dmaengine_submit() is called.
This patch fixes the workflow in dw_dmac driver to follow the documentation.
[1] http://www.spinics.net/lists/arm-kernel/msg125987.html
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Cc: "Petallo, MauriceX R" <mauricex.r.petallo@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/dma/TODO | 1 -
drivers/dma/dw/core.c | 19 +++++++------------
2 files changed, 7 insertions(+), 13 deletions(-)
--- a/drivers/dma/TODO
+++ b/drivers/dma/TODO
@@ -7,7 +7,6 @@ TODO for slave dma
- imx-dma
- imx-sdma
- mxs-dma.c
- - dw_dmac
- intel_mid_dma
4. Check other subsystems for dma drivers and merge/move to dmaengine
5. Remove dma_slave_config's dma direction.
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -680,17 +680,9 @@ static dma_cookie_t dwc_tx_submit(struct
* possible, perhaps even appending to those already submitted
* for DMA. But this is hard to do in a race-free manner.
*/
- if (list_empty(&dwc->active_list)) {
- dev_vdbg(chan2dev(tx->chan), "%s: started %u\n", __func__,
- desc->txd.cookie);
- list_add_tail(&desc->desc_node, &dwc->active_list);
- dwc_dostart(dwc, dwc_first_active(dwc));
- } else {
- dev_vdbg(chan2dev(tx->chan), "%s: queued %u\n", __func__,
- desc->txd.cookie);
- list_add_tail(&desc->desc_node, &dwc->queue);
- }
+ dev_vdbg(chan2dev(tx->chan), "%s: queued %u\n", __func__, desc->txd.cookie);
+ list_add_tail(&desc->desc_node, &dwc->queue);
spin_unlock_irqrestore(&dwc->lock, flags);
@@ -1095,9 +1087,12 @@ dwc_tx_status(struct dma_chan *chan,
static void dwc_issue_pending(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
+ unsigned long flags;
- if (!list_empty(&dwc->queue))
- dwc_scan_descriptors(to_dw_dma(chan->device), dwc);
+ spin_lock_irqsave(&dwc->lock, flags);
+ if (list_empty(&dwc->active_list))
+ dwc_dostart_first_queued(dwc);
+ spin_unlock_irqrestore(&dwc->lock, flags);
}
static int dwc_alloc_chan_resources(struct dma_chan *chan)
Patches currently in stable-queue which might be from andriy.shevchenko@xxxxxxxxxxxxxxx are
queue-3.16/dmaengine-dw-introduce-dwc_dostart_first_queued-helper.patch
queue-3.16/dmaengine-dw-don-t-perform-dma-when-dmaengine_submit-is-called.patch
queue-3.16/spi-dw-pci-fix-bug-when-regs-left-uninitialized.patch
queue-3.16/spi-dw-fix-kernel-crash-due-to-null-pointer-dereference.patch
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