From: vinod.koul@intel.com (Vinod Koul)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/3] dma: Add Freescale eDMA engine driver support
Date: Mon, 23 Sep 2013 09:55:49 +0530 [thread overview]
Message-ID: <20130923042549.GC17188@intel.com> (raw)
In-Reply-To: <B56CDBE15CE27145A4B77D2D24263E85223E21@039-SN1MPN1-003.039d.mgd.msft.net>
On Tue, Sep 17, 2013 at 08:08:46AM +0000, Lu Jingchang-B35083 wrote:
> > > + case DMA_PAUSE:
> > > + if (fsl_chan->edesc)
> > > + fsl_edma_disable_request(fsl_chan);
> > racy here too...
> It only set the channel HW register, no list is handled,
> is lock needed here? Thanks!
well thats the point while you are terminating the current trasnaction can
complete and then start another one. You want to try and prevent these case
also. Here you are neither locking the HW access nor the the list, so its juts
waiting to crash!
~Vinod
--
WARNING: multiple messages have this Message-ID (diff)
From: Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
To: Lu Jingchang-B35083 <B35083-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
Cc: "djbw-b10kYP2dOMg@public.gmane.org"
<djbw-b10kYP2dOMg@public.gmane.org>,
"shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org"
<shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH 3/3] dma: Add Freescale eDMA engine driver support
Date: Mon, 23 Sep 2013 09:55:49 +0530 [thread overview]
Message-ID: <20130923042549.GC17188@intel.com> (raw)
In-Reply-To: <B56CDBE15CE27145A4B77D2D24263E85223E21-TcFNo7jSaXOLgTCmFNXF2K4g8xLGJsHaLnY5E4hWTkheoWH0uzbU5w@public.gmane.org>
On Tue, Sep 17, 2013 at 08:08:46AM +0000, Lu Jingchang-B35083 wrote:
> > > + case DMA_PAUSE:
> > > + if (fsl_chan->edesc)
> > > + fsl_edma_disable_request(fsl_chan);
> > racy here too...
> It only set the channel HW register, no list is handled,
> is lock needed here? Thanks!
well thats the point while you are terminating the current trasnaction can
complete and then start another one. You want to try and prevent these case
also. Here you are neither locking the HW access nor the the list, so its juts
waiting to crash!
~Vinod
--
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WARNING: multiple messages have this Message-ID (diff)
From: Vinod Koul <vinod.koul@intel.com>
To: Lu Jingchang-B35083 <B35083@freescale.com>
Cc: "djbw@fb.com" <djbw@fb.com>,
"shawn.guo@linaro.org" <shawn.guo@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH 3/3] dma: Add Freescale eDMA engine driver support
Date: Mon, 23 Sep 2013 09:55:49 +0530 [thread overview]
Message-ID: <20130923042549.GC17188@intel.com> (raw)
In-Reply-To: <B56CDBE15CE27145A4B77D2D24263E85223E21@039-SN1MPN1-003.039d.mgd.msft.net>
On Tue, Sep 17, 2013 at 08:08:46AM +0000, Lu Jingchang-B35083 wrote:
> > > + case DMA_PAUSE:
> > > + if (fsl_chan->edesc)
> > > + fsl_edma_disable_request(fsl_chan);
> > racy here too...
> It only set the channel HW register, no list is handled,
> is lock needed here? Thanks!
well thats the point while you are terminating the current trasnaction can
complete and then start another one. You want to try and prevent these case
also. Here you are neither locking the HW access nor the the list, so its juts
waiting to crash!
~Vinod
--
next prev parent reply other threads:[~2013-09-23 4:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-05 9:53 [PATCH 3/3] dma: Add Freescale eDMA engine driver support Jingchang Lu
2013-09-05 9:53 ` Jingchang Lu
2013-09-05 9:53 ` Jingchang Lu
2013-09-17 4:53 ` Vinod Koul
2013-09-17 4:53 ` Vinod Koul
2013-09-17 4:53 ` Vinod Koul
2013-09-17 7:37 ` Lu Jingchang-B35083
2013-09-17 7:37 ` Lu Jingchang-B35083
2013-09-17 7:37 ` Lu Jingchang-B35083
2013-09-17 8:08 ` Lu Jingchang-B35083
2013-09-17 8:08 ` Lu Jingchang-B35083
2013-09-17 8:08 ` Lu Jingchang-B35083
2013-09-23 4:25 ` Vinod Koul [this message]
2013-09-23 4:25 ` Vinod Koul
2013-09-23 4:25 ` Vinod Koul
2013-09-23 6:56 ` Lu Jingchang-B35083
2013-09-23 6:56 ` Lu Jingchang-B35083
2013-09-23 6:56 ` Lu Jingchang-B35083
-- strict thread matches above, loose matches on Subject: below --
2013-08-02 7:55 [PATCH 1/3] ARM: imx: Add DMAMUX clock for Vybrid vf610 SoC Jingchang Lu
2013-08-02 7:55 ` [PATCH 3/3] dma: Add Freescale eDMA engine driver support Jingchang Lu
2013-08-02 7:55 ` Jingchang Lu
2013-08-04 13:55 ` Shawn Guo
2013-08-04 13:55 ` Shawn Guo
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