Hi Mark: > From: alsa-devel-boun...@alsa-project.org > [mailto:alsa-devel-boun...@alsa-project.org] On Behalf Of yitian > Sent: Thursday, October 1, 2015 10:25 AM > To: 'Mark Brown' <broo...@kernel.org> > Cc: alsa-de...@alsa-project.org; w...@the-dreams.de; > linux-kernel@vger.kernel.org; andrew.jack...@arm.com; > lgirdw...@gmail.com; ti...@suse.com; > linux-arm-ker...@lists.infradead.org > Subject: Re: [alsa-devel] [RESEND PATCH v2 1/1] ASoC: dwc: fix dma stop > transferring issue > > > From: linux-arm-kernel > > [mailto:linux-arm-kernel-boun...@lists.infradead.org] On Behalf Of > Mark > > Brown > > Sent: Thursday, October 1, 2015 2:22 AM > > To: yitian <yitian...@tangramtek.com> > > Cc: alsa-de...@alsa-project.org; w...@the-dreams.de; > > linux-kernel@vger.kernel.org; andrew.jack...@arm.com; > ti...@suse.com; > > lgirdw...@gmail.com; pe...@perex.cz; > > linux-arm-ker...@lists.infradead.org > > Subject: Re: [RESEND PATCH v2 1/1] ASoC: dwc: fix dma stop transferring > > issue > > > > On Tue, Sep 29, 2015 at 10:43:17PM +0800, yitian wrote: > > > Designware I2S uses tx empty and rx available signals as the DMA > > > handshaking signals. during music playing, if XRUN occurs, > > > i2s_stop() function will be executed and both tx and rx irq are > > > masked, when music continues to be played, i2s_start() is executed > > > but both tx and rx irq are not unmasked which cause I2S stop > > > sending DMA handshaking signal to DMA controller, and it finally > > > causes music playing will be stopped once XRUN occurs for the first > > > time. > > > > I'm a bit concerned about how this code ever worked given the above > > description - is there some race condition which allows things to work > > if we're lucky? > > Hi Mark: > > Thanks for your comments. > I think maybe two reasons: > 1. designware I2S IP in my chipset(new design) is using tx empty and rx > available signal as the DMA handshaking signal, but it may be not true > for all chipsets. If I2S has separate signal as DMA handshaking signal, mask > irq should not impact DMA transfer. But Synopsys's engineer recommend > us to > use > tx and rx irq signal as the DMA handshaking signal, meanwhile we cannot > find > separate DMA handshaking signal from designware's IP spec, that's why > tx/rx > irq > will impact DMA transfer. > > 2. I am using a FPGA for test, the cpu frequency of it is only 26MHz, that > means > XRUN is very easy to happen on my board. But I guess most of the > developers > are using real chipset which can have at least 600MHz frequency so XRUN > is > not easy to be reproduced. As my test, No XUN, no this bug...
Do I need to provide anything else for this patch? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
