我的alsa driver裡,在open function裡request_irq
在close function裡free_irq
當執行aplay 播放一段聲音,irq callback function開始中斷
然後停了,程序沒有正常結束,那個部份可能我還沒處理好,我用ctrl+c結束
[snd_nxc2600_trigger] : Leave
l Interrupt...
[snd_nxc2600_playback_trigger] : Leave
[snd_nxc2600_close] : Enter
Trying to free free IRQ4
[snd_nxc2600_close] : Leave

然後看cat /proc/interrupts
           CPU0
  4:          1   wb audio
  5:          0   w90x900-lcd
  7:        337   w90x900-uart
 12:      17293   w90x900 Timer Tick
 15:        395   ehci_hcd:usb1
 16:         21   w90x900-MAC
 17:        169   w90x900-MAC
 19:          0   W90X900_DMAC
 20:          1   W90X900_SD
Err:          0

4號中斷沒被free,為什麼呢,再執行一次aplay
./aplay ringback.wav
[snd_nxc2600_playback_open] : Enter
wb_audio_init : Request IRQ error
Trying to free free IRQ4
aplay: main:546: audio open error: Operation not permitted

就不能播了,我把全部ac97的moduel都remove再cat /proc/interrupts
Unable to handle kernel paging request at virtual address bf03d880
pgd = c03e0000
[bf03d880] *pgd=00e6a011, *pte=00000000, *ppte=00000000
Internal error: Oops: 7 [#1]
Modules linked in:
CPU: 0
PC is at strnlen+0x20/0x34
LR is at vsnprintf+0x300/0x5b4
pc : []    lr : []    Not tainted
sp : c0f01e48  ip : c0f01e58  fp : c0f01e54
r10: ffffffff  r9 : c0fd3fff  r8 : 00000000
r7 : c0f01ec8  r6 : c0fd3022  r5 : c0868d20  r4 : bf03d880
r3 : c0229624  r2 : bf03d880  r1 : fffffffe  r0 : bf03d880
Flags: NzCv  IRQs off  FIQs on  Mode SVC_32  Segment user
Control: 5317F  Table: 003E0000  DAC: 00000015
Process cat (pid: 838, stack limit = 0xc0f001a0)
Stack: (0xc0f01e48 to 0xc0f02000)
1e40:                   c0f01ea4 c0f01e58 c012b510 c012a3ac 0000000a 0000000a
1e60: ffffffff 00000000 00000056 00000fe0 c0fd3020 c0218ddb c005f224 c0868d20
1e80: c0868d20 80000013 00000000 00000004 00000000 00000010 c0f01ec0 c0f01ea8
1ea0: c0095328 c012b220 c0dde530 c0f01ec8 c0e17920 c0f01f04 c0f01ed0 c002151c
1ec0: c00952f4 c0218dd8 bf03d880 00000015 bec69c08 30555043 c0f00000 00000000
1ee0: c0f01f04 c0f01f18 00000000 c0868d20 bec69c08 00001000 c0f01f54 c0f01f08
1f00: c0095968 c0021458 c0f01f78 c0304c60 c0868d40 00000000 00000004 00000000
1f20: 00000003 00000000 c0f01f7c c0304c60 bec69c08 c0f01f78 00001000 c001ff68
1f40: c0f00000 00000000 c0f01f74 c0f01f58 c0071854 c0095744 00000000 00000000
1f60: c0304c60 00000003 c0f01fa4 c0f01f78 c0071d28 c00717b4 00000000 00000000
1f80: 00000005 00000000 ffffffff 00001000 bec69c08 00000003 00000000 c0f01fa8
1fa0: c001fdc0 c0071cf4 00001000 bec69c08 00000003 bec69c08 00001000 00000001
1fc0: 00001000 bec69c08 00000003 00000003 00000000 bec69c08 00000001 00000003
1fe0: 00000002 bec69be0 0000a42c 0005e024 60000010 00000003 2043494d 204d4350
Backtrace:
[] (strnlen+0x0/0x34) from [] (vsnprintf+0x300/0x5b4)
[] (vsnprintf+0x0/0x5b4) from [] (seq_printf+0x48/0x7c)
[] (seq_printf+0x0/0x7c) from [] (show_interrupts+0xd4/0x16c)
 r3 = 00000015  r2 = BF03D880  r1 = C0218DD8
 r4 = C0E17920
[] (show_interrupts+0x0/0x16c) from [] (seq_read+0x234/0x378)
 r8 = 00001000  r7 = BEC69C08  r6 = C0868D20  r5 = 00000000
 r4 = C0F01F18
[] (seq_read+0x0/0x378) from [] (vfs_read+0xb0/0x17c)
[] (vfs_read+0x0/0x17c) from [] (sys_read+0x44/0x70)
 r7 = 00000003  r6 = C0304C60  r5 = 00000000  r4 = 00000000
[] (sys_read+0x0/0x70) from [] (ret_fast_syscall+0x0/0x2c)
 r6 = 00000003  r5 = BEC69C08  r4 = 00001000
Code: ea000000 e2800001 e2511001 3a000002 (e5d03000)
 note: cat[838] exited with preempt_count 1
Segmentation fault

再全部insert module一次 cat /proc/interrupts
           CPU0
  4:          1   wb audio
  5:          0   w90x900-lcd
  7:        461   w90x900-uart
 12:      39498   w90x900 Timer Tick
 15:        427   ehci_hcd:usb1
 16:         34   w90x900-MAC
 17:        394   w90x900-MAC
 19:          0   W90X900_DMAC
 20:          1   W90X900_SD
Err:          0
又正常了
./aplay ringback.wav
[snd_nxc2600_playback_open] : Enter
wb_audio_init : Request IRQ error
Trying to free free IRQ4
aplay: main:546: audio open error: Operation not permitted
還是不行,為什麼free_irq不行呢?每次執行ap一次不就會request_irq一次
那是代表只能被單一ap獨佔嗎

static int snd_nxc2600_playback_open(struct snd_pcm_substream *substream)

{

   int err;                                                                           ENTER();

   struct snd_nxc2600 *nxc2600 = substream->pcm->private_data;



   //   if(nxc2600->playback.channel == NULL)

   //           return -EBUSY;



   nxc2600->playback.substream = substream;

   substream->private_data = &nxc2600->playback;

   substream->runtime->hw = snd_nxc2600_hw;

   //========================================

   if((err = request_irq(IRQ_ACTL, wb_dsp_irq, SA_INTERRUPT, "wb audio", nxc2600)))   {

      printk("Request IRQ error=%dn",err);                                              snd_card_free(nxc2600_card);

      return -1;                                                                      }

   //=========================================                                        memset(&play_half_buf, 0, sizeof(play_half_buf));

   memset(&record_half_buf, 0, sizeof(record_half_buf));



   LEAVE();

   return (snd_pcm_hw_constraint_list(substream->runtime, 0,

            SNDRV_PCM_HW_PARAM_RATE, &hw_constraints_rates) private_data;

   spin_lock_irq(&stream->dma_lock);                                                  //nxc2600_dma_stop(stream);

                                                                                   

   Disable_Int(AU_PLAY_INT_NUM);

   free_irq(IRQ_ACTL, NULL);

   spin_unlock_irq(&stream->dma_lock);

   stream->substream = NULL;

   LEAVE();                                                                           return 0;

}

然後看cat /proc/interrupts 
          CPU0 
  4:          1  wb audio 
  5:          0  w90x900-lcd 
  7:        337  w90x900-uart 
12:      17293  w90x900 Timer Tick 
15:        395  ehci_hcd:usb1 
16:        21  w90x900-MAC 
17:        169  w90x900-MAC 
19:          0  W90X900_DMAC 
20:          1  W90X900_SD 
Err:          0 

4號中斷沒被free,為什麼呢,再執行一次aplay 

free_irq没有操作成功.

这个中断只是处理与硬件的交互，与有几个应用没有关系。与应用相关的是你的驱动是否
支持多次 open，只要处理好每次读写的数据不会互相重叠（包括硬件上），并能正确的
反映到硬件上去。一般驱动会有一个缓存的动作，将多次读写数据进行排队，避免冲突。

        if (request_irq(pci->irq, irq_handler, IRQF_SHARED,

                        card->shortname, chip)) {

                snd_printk(KERN_ERR "unable to grab IRQ %dn", pci->irq);

                snd_als300_free(chip);

                return -EBUSY;

        }

        chip->irq = pci->irq;

还有注册时，pci 上的中断一般采用共享中断方式注册。

呵呵，最后顺便提一句：还请兄弟支持一下我升星星吧...