imx sgtl5000:BUG: scheduling while atomic: speaker-test/1225/0x00000003
Lothar Waßmann
LW at KARO-electronics.de
Thu Apr 26 02:10:35 EDT 2012
Hi,
[added CC: Sascha Hauer as the SDMA driver author]
Richard Zhao writes:
> On Thu, Apr 26, 2012 at 10:33:21AM +0800, Richard Zhao wrote:
> > [ 13.901890] eth0: no IPv6 routers present
> > [ 70.295079] BUG: scheduling while atomic: speaker-test/1225/0x00000003
> > [ 70.304293] Modules linked in:
> > [ 70.310389] [<c0015a68>] (unwind_backtrace+0x0/0xec) from [<c0585810>] (dump_stack+0x20/0x24)
> > [ 70.310421] [<c0585810>] (dump_stack+0x20/0x24) from [<c0585f6c>] (__schedule_bug+0x54/0x60)
> > [ 70.310452] [<c0585f6c>] (__schedule_bug+0x54/0x60) from [<c058db64>] (__schedule+0x84/0x748)
> > [ 70.310476] [<c058db64>] (__schedule+0x84/0x748) from [<c058e310>] (schedule+0x8c/0x90)
> > [ 70.310500] [<c058e310>] (schedule+0x8c/0x90) from [<c058c504>] (schedule_timeout+0x2fc/0x35c)
> > [ 70.310541] [<c058c504>] (schedule_timeout+0x2fc/0x35c) from [<c058d970>] (wait_for_common+0xd8/0x16c)
> > [ 70.310567] [<c058d970>] (wait_for_common+0xd8/0x16c) from [<c058da44>] (wait_for_completion_timeout+0x1c/0x20)
> > [ 70.310604] [<c058da44>] (wait_for_completion_timeout+0x1c/0x20) from [<c03352bc>] (sdma_run_channel+0x70/0x8c)
> > [ 70.310634] [<c03352bc>] (sdma_run_channel+0x70/0x8c) from [<c0335614>] (sdma_load_context+0x188/0x19c)
> > [ 70.310661] [<c0335614>] (sdma_load_context+0x188/0x19c) from [<c0335688>] (sdma_prep_dma_cyclic+0x60/0x1a8)
> > [ 70.310694] [<c0335688>] (sdma_prep_dma_cyclic+0x60/0x1a8) from [<c04760f4>] (snd_dmaengine_pcm_trigger+0xa0/0x134)
> > [ 70.310729] [<c04760f4>] (snd_dmaengine_pcm_trigger+0xa0/0x134) from [<c0483e68>] (soc_pcm_trigger+0x74/0xb0)
> > [ 70.310770] [<c0483e68>] (soc_pcm_trigger+0x74/0xb0) from [<c046e670>] (snd_pcm_do_start+0x34/0x40)
> > [ 70.310797] [<c046e670>] (snd_pcm_do_start+0x34/0x40) from [<c046e288>] (snd_pcm_action_single+0x48/0x74)
> > [ 70.310823] [<c046e288>] (snd_pcm_action_single+0x48/0x74) from [<c046e334>] (snd_pcm_action+0x80/0x8c)
> > [ 70.310850] [<c046e334>] (snd_pcm_action+0x80/0x8c) from [<c04707f0>] (snd_pcm_start+0x24/0x2c)
> > [ 70.310877] [<c04707f0>] (snd_pcm_start+0x24/0x2c) from [<c0474058>] (snd_pcm_lib_write1+0x2a8/0x340)
> > [ 70.310900] [<c0474058>] (snd_pcm_lib_write1+0x2a8/0x340) from [<c04741d0>] (snd_pcm_lib_write+0x70/0x7c)
> > [ 70.311007] [<c04741d0>] (snd_pcm_lib_write+0x70/0x7c) from [<c04703f8>] (snd_pcm_playback_ioctl1+0x114/0x428)
> > [ 70.311038] [<c04703f8>] (snd_pcm_playback_ioctl1+0x114/0x428) from [<c0470744>] (snd_pcm_playback_ioctl+0x38/0x44)
> > [ 70.311077] [<c0470744>] (snd_pcm_playback_ioctl+0x38/0x44) from [<c0107234>] (do_vfs_ioctl+0x4f4/0x568)
> > [ 70.311105] [<c0107234>] (do_vfs_ioctl+0x4f4/0x568) from [<c0107308>] (sys_ioctl+0x60/0x84)
> > [ 70.311138] [<c0107308>] (sys_ioctl+0x60/0x84) from [<c000df40>] (ret_fast_syscall+0x0/0x30)
> > [ 80.301928] ALSA sound/core/pcm_lib.c:1853 playback write error (DMA or IRQ trouble?)
> >
> >
> > kernel: 3.4rc3 with ASoC/for-next and some my patches.
>
> I found the cause.
> snd_dmaengine_pcm_trigger --> dmaengine_pcm_prepare_and_submit
> --> dmaengine_prep_dma_cyclic
>
> The trigger function is in atomic context, but dmaengine_prep_dma_cyclic
> tried to sleep.
>
> From dma engine design, can device_prep_dma_cyclic sleep?
> If yes, we may need to move it out of trigger functions.
>
The root cause is that sdma_run_channel does a
wait_for_completion_timeout() to wait for the special channel 0 to
complete which is complete overkill from my point of view.
channel 0 is used internally in the DMA engine and should always
complete within a few microseconds. Thus a busy loop with a timeout
would be fine here.
Furthermore a mutex is used to serialize access to channel data
structures which also forbids the affected function to be used in
interrupt context.
The following patch would fix that:
diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index d3e38e2..fcab768 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -24,7 +24,7 @@
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
-#include <linux/wait.h>
+#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/spinlock.h>
@@ -323,7 +323,7 @@ struct sdma_engine {
dma_addr_t context_phys;
struct dma_device dma_device;
struct clk *clk;
- struct mutex channel_0_lock;
+ spinlock_t channel_0_lock;
struct sdma_script_start_addrs *script_addrs;
};
@@ -408,12 +408,21 @@ static int sdma_run_channel(struct sdma_channel *sdmac)
struct sdma_engine *sdma = sdmac->sdma;
int channel = sdmac->channel;
int ret;
-
- init_completion(&sdmac->done);
+ unsigned long timeout = 500;
sdma_enable_channel(sdma, channel);
- ret = wait_for_completion_timeout(&sdmac->done, HZ);
+ while (!(ret = readl_relaxed(sdma->regs + SDMA_H_INTR) & 1)) {
+ if (timeout-- <= 0)
+ break;
+ udelay(1);
+ }
+ if (ret) {
+ /* Clear the interrupt status */
+ writel_relaxed(ret, sdma->regs + SDMA_H_INTR);
+ } else {
+ dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
+ }
return ret ? 0 : -ETIMEDOUT;
}
@@ -425,17 +434,17 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
void *buf_virt;
dma_addr_t buf_phys;
int ret;
-
- mutex_lock(&sdma->channel_0_lock);
+ unsigned long flags;
buf_virt = dma_alloc_coherent(NULL,
size,
&buf_phys, GFP_KERNEL);
if (!buf_virt) {
- ret = -ENOMEM;
- goto err_out;
+ return -ENOMEM;
}
+ spin_lock_irqsave(&sdma->channel_0_lock, flags);
+
bd0->mode.command = C0_SETPM;
bd0->mode.status = BD_DONE | BD_INTR | BD_WRAP | BD_EXTD;
bd0->mode.count = size / 2;
@@ -446,10 +455,9 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
ret = sdma_run_channel(&sdma->channel[0]);
- dma_free_coherent(NULL, size, buf_virt, buf_phys);
+ spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
-err_out:
- mutex_unlock(&sdma->channel_0_lock);
+ dma_free_coherent(NULL, size, buf_virt, buf_phys);
return ret;
}
@@ -539,7 +547,7 @@ static void mxc_sdma_handle_channel(struct sdma_channel *sdmac)
complete(&sdmac->done);
/* not interested in channel 0 interrupts */
- if (sdmac->channel == 0)
+ if (WARN_ON(sdmac->channel == 0))
return;
if (sdmac->flags & IMX_DMA_SG_LOOP)
@@ -659,6 +667,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
struct sdma_context_data *context = sdma->context;
struct sdma_buffer_descriptor *bd0 = sdma->channel[0].bd;
int ret;
+ unsigned long flags;
if (sdmac->direction == DMA_DEV_TO_MEM) {
load_address = sdmac->pc_from_device;
@@ -676,7 +685,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
dev_dbg(sdma->dev, "event_mask0 = 0x%08x\n", (u32)sdmac->event_mask[0]);
dev_dbg(sdma->dev, "event_mask1 = 0x%08x\n", (u32)sdmac->event_mask[1]);
- mutex_lock(&sdma->channel_0_lock);
+ spin_lock_irqsave(&sdma->channel_0_lock, flags);
memset(context, 0, sizeof(*context));
context->channel_state.pc = load_address;
@@ -698,7 +707,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
ret = sdma_run_channel(&sdma->channel[0]);
- mutex_unlock(&sdma->channel_0_lock);
+ spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
return ret;
}
@@ -1297,7 +1306,7 @@ static int __init sdma_probe(struct platform_device *pdev)
if (!sdma)
return -ENOMEM;
- mutex_init(&sdma->channel_0_lock);
+ spin_lock_init(&sdma->channel_0_lock);
sdma->dev = &pdev->dev;
Lothar Waßmann
--
___________________________________________________________
Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________
More information about the linux-arm-kernel
mailing list