| Message ID | 025c01d0f858$4d19c790$e74d56b0$@tangramtek.com (mailing list archive) |
|---|---|
| State | Rejected |
| Headers | show |
On 26 September 2015 at 05:38, yitian <yitian.bu@tangramtek.com> wrote: > when audio playback is running, user space will call > snd_pcm_lib_write1() function, it will first get pcm stream lock, > after that it may call function snd_pcm_update_hw_ptr(), the call > stack will be as below: > snd_pcm_lib_write1 <-- got pcm stream lock > --> snd_pcm_update_hw_ptr > --> dwc_tx_status > --> dwc_scan_descriptors > --> callback > --> dmaengine_pcm_dma_complete > --> snd_pcm_period_elapsed <-- get stream lock again > recursion lock occurs in snd_pcm_period_elapsed function. > remove dwc_scan_descriptors from dwc_tx_status can fix this issue. > > Signed-off-by: Yitian Bu <yitian.bu@tangramtek.com> > --- > drivers/dma/dw/core.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) I am not sure if this is a sane way of doing that, and we were scanning the descriptors for some valid reason.. Though, I am on vacation for few days now and will be able to look at the details later. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Sep 28, 2015 at 6:23 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > On 26 September 2015 at 05:38, yitian <yitian.bu@tangramtek.com> wrote: >> when audio playback is running, user space will call >> snd_pcm_lib_write1() function, it will first get pcm stream lock, >> after that it may call function snd_pcm_update_hw_ptr(), the call >> stack will be as below: >> snd_pcm_lib_write1 <-- got pcm stream lock >> --> snd_pcm_update_hw_ptr >> --> dwc_tx_status >> --> dwc_scan_descriptors >> --> callback >> --> dmaengine_pcm_dma_complete >> --> snd_pcm_period_elapsed <-- get stream lock again >> recursion lock occurs in snd_pcm_period_elapsed function. >> remove dwc_scan_descriptors from dwc_tx_status can fix this issue. >> >> Signed-off-by: Yitian Bu <yitian.bu@tangramtek.com> >> --- >> drivers/dma/dw/core.c | 6 +----- >> 1 file changed, 1 insertion(+), 5 deletions(-) > > I am not sure if this is a sane way of doing that, and we were scanning > the descriptors for some valid reason.. Actually one of the patches in a pile sitting in my private repo is also including similar change. In my case the reason is to support cyclic transfers natively. > Though, I am on vacation for few days now and will be able to look > at the details later. Have a good rest then!
> From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com] > Sent: Monday, September 28, 2015 3:06 PM > To: Viresh Kumar <viresh.kumar@linaro.org> > Cc: yitian <yitian.bu@tangramtek.com>; Viresh Kumar > <vireshk@kernel.org>; Andy Shevchenko > <andriy.shevchenko@linux.intel.com>; Vinod Koul <vinod.koul@intel.com>; > Dan Williams <dan.j.williams@intel.com>; dmaengine > <dmaengine@vger.kernel.org>; Linux Kernel Mailing List > <linux-kernel@vger.kernel.org> > Subject: Re: [PATCH 1/1] dmaengine: dw: resolve recursion > > I am not sure if this is a sane way of doing that, and we were scanning > > the descriptors for some valid reason.. > > Actually one of the patches in a pile sitting in my private repo is > also including similar change. In my case the reason is to support > cyclic transfers natively. > Yes, i am using DW DMAC to support cyclic transfer. Currently it is very easy to get recursion lock crash, but after this patch everything is fine on my device. I am waiting for your further guide. Thanks. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2015-09-28 at 15:23 +0800, yitian wrote: > > > > From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com] > > Sent: Monday, September 28, 2015 3:06 PM > > To: Viresh Kumar <viresh.kumar@linaro.org> > > Cc: yitian <yitian.bu@tangramtek.com>; Viresh Kumar > > <vireshk@kernel.org>; Andy Shevchenko > > <andriy.shevchenko@linux.intel.com>; Vinod Koul < > > vinod.koul@intel.com>; > > Dan Williams <dan.j.williams@intel.com>; dmaengine > > <dmaengine@vger.kernel.org>; Linux Kernel Mailing List > > <linux-kernel@vger.kernel.org> > > Subject: Re: [PATCH 1/1] dmaengine: dw: resolve recursion > > > I am not sure if this is a sane way of doing that, and we were > > > scanning > > > the descriptors for some valid reason.. > > > > Actually one of the patches in a pile sitting in my private repo is > > also including similar change. In my case the reason is to support > > cyclic transfers natively. > > > > Yes, i am using DW DMAC to support cyclic transfer. > Currently it is very easy to get recursion lock crash, but > after this patch everything is fine on my device. What is an actual hardware you are running kernel on?
> From: Andy Shevchenko [mailto:andriy.shevchenko@linux.intel.com] > Sent: Monday, September 28, 2015 4:46 PM > To: yitian <yitian.bu@tangramtek.com>; 'Andy Shevchenko' > <andy.shevchenko@gmail.com>; 'Viresh Kumar' <viresh.kumar@linaro.org> > Cc: 'Viresh Kumar' <vireshk@kernel.org>; 'Vinod Koul' > <vinod.koul@intel.com>; 'Dan Williams' <dan.j.williams@intel.com>; > 'dmaengine' <dmaengine@vger.kernel.org>; 'Linux Kernel Mailing List' > <linux-kernel@vger.kernel.org> > Subject: Re: [PATCH 1/1] dmaengine: dw: resolve recursion lock when > audio playback > > On Mon, 2015-09-28 at 15:23 +0800, yitian wrote: > > > > > > From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com] > > > Sent: Monday, September 28, 2015 3:06 PM > > > To: Viresh Kumar <viresh.kumar@linaro.org> > > > Cc: yitian <yitian.bu@tangramtek.com>; Viresh Kumar > > > <vireshk@kernel.org>; Andy Shevchenko > > > <andriy.shevchenko@linux.intel.com>; Vinod Koul < > > > vinod.koul@intel.com>; > > > Dan Williams <dan.j.williams@intel.com>; dmaengine > > > <dmaengine@vger.kernel.org>; Linux Kernel Mailing List > > > <linux-kernel@vger.kernel.org> > > > Subject: Re: [PATCH 1/1] dmaengine: dw: resolve recursion > > > > I am not sure if this is a sane way of doing that, and we were > > > > scanning > > > > the descriptors for some valid reason.. > > > > > > Actually one of the patches in a pile sitting in my private repo is > > > also including similar change. In my case the reason is to support > > > cyclic transfers natively. > > > > > > > Yes, i am using DW DMAC to support cyclic transfer. > > Currently it is very easy to get recursion lock crash, but > > after this patch everything is fine on my device. > > What is an actual hardware you are running kernel on? > Hi Andy: I am using a FPGA, with Cortex-A5 core, Designware I2S IP, Designware DMAC IP. What I was done is to run tinyplay and tinycap to test the playback and capture function on the FPGA. With my change, both of them are okay now. I didn't push the patch which added cyclic DMA support for dw DMAC because I didn't make it decent enough yet. -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c index cf1c87f..5341b44 100644 --- a/drivers/dma/dw/core.c +++ b/drivers/dma/dw/core.c @@ -1078,11 +1078,7 @@ dwc_tx_status(struct dma_chan *chan, ret = dma_cookie_status(chan, cookie, txstate); if (ret == DMA_COMPLETE) return ret; - - dwc_scan_descriptors(to_dw_dma(chan->device), dwc); - - ret = dma_cookie_status(chan, cookie, txstate); - if (ret != DMA_COMPLETE) + else dma_set_residue(txstate, dwc_get_residue(dwc)); if (dwc->paused && ret == DMA_IN_PROGRESS)
when audio playback is running, user space will call snd_pcm_lib_write1() function, it will first get pcm stream lock, after that it may call function snd_pcm_update_hw_ptr(), the call stack will be as below: snd_pcm_lib_write1 <-- got pcm stream lock --> snd_pcm_update_hw_ptr --> dwc_tx_status --> dwc_scan_descriptors --> callback --> dmaengine_pcm_dma_complete --> snd_pcm_period_elapsed <-- get stream lock again recursion lock occurs in snd_pcm_period_elapsed function. remove dwc_scan_descriptors from dwc_tx_status can fix this issue. Signed-off-by: Yitian Bu <yitian.bu@tangramtek.com> --- drivers/dma/dw/core.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)