From: Vinod Koul <vinod.koul@intel.com>
To: Dylan Reid <dgreid@chromium.org>
Cc: Chanho Park <chanho61.park@samsung.com>,
Padmavathi Venna <padma.v@samsung.com>,
linux-samsung-soc@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Padma Venkat <padma.kvr@gmail.com>,
kgene.kim@samsung.com, Arnd Bergmann <arnd@arndb.de>,
Sangbeom Kim <sbkim73@samsung.com>,
Mark Brown <broonie@kernel.org>,
Olof Johansson <olofj@chromium.org>
Subject: Re: [PATCH 1/3] dmaengine: pl330: Set residue in tx_status callback.
Date: Thu, 10 Oct 2013 21:28:55 +0530 [thread overview]
Message-ID: <20131010155855.GA2954@intel.com> (raw)
In-Reply-To: <CAEUnVG7Xn8+Xhnr2y5-RM6FJTQsjRrJ9g1JWf4o+6B-BtWHbPA@mail.gmail.com>
On Wed, Oct 09, 2013 at 01:37:56PM -0700, Dylan Reid wrote:
> On Sun, Oct 6, 2013 at 8:48 PM, Vinod Koul <vinod.koul@intel.com> wrote:
> > On Mon, Oct 07, 2013 at 10:39:34AM +0900, Chanho Park wrote:
> >> > > Why didn't you use a cookie value to track the request?
> >> > > The cookie is assigned when each transfer is submitted.
> >> > > If you save the value in the desc, we can find the request easily.
> >> >
> >> > If there are several cyclic desc in the work list, is there a better way
> >> > to find the "current" one? The chan struct tracks the last completed and
> >> > last submitted cookies, but these will be the first and last
> >> > respectively as long as the cyclic transfer is active. Is there an
> >> > "active" cookie stored somewhere that I missed?
> >>
> >> Assume there are three cookies. If you want to get the second cookie not
> >> latest cookie, your way can be also correct in such case?
> >> I think tx_status API is to get dma status of the given cookie.
> >> You are only considering a cyclic case.
> > For cyclic case you would have possible same descriptor running till you
> > terminate.
>
> The cyclic case that makes this interesting is when there are multiple
> cyclic descriptors in the list. The cookie and completed_cookie
> markers don't help to determine which of the descriptors in the list
> is currently active. dma_cookie_complete isn't called for a cyclic
> desc, the desc is just pushed to the end of the list.
Yes the cyclic is a very different case. I think driver can still return for
cyclic case which was txstate->last and that will give clue to client which is
getting processed now!
> > For non cyclic, if you have 3 descriptors submitted, the cookie value can be, say
> > 7, 8 and 9. If you query the status of any descriptor and pass the last optional
> > txstate arg then you will know the last cookie completed. so if txstate->last is
> > 7, then 7th was completed and 8 should be running and 9 in queue!
>
> Got it, but the correct desc for cookie 8 will still have to be
> searched for, correct?
Yes
--
~Vinod
WARNING: multiple messages have this Message-ID (diff)
From: vinod.koul@intel.com (Vinod Koul)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/3] dmaengine: pl330: Set residue in tx_status callback.
Date: Thu, 10 Oct 2013 21:28:55 +0530 [thread overview]
Message-ID: <20131010155855.GA2954@intel.com> (raw)
In-Reply-To: <CAEUnVG7Xn8+Xhnr2y5-RM6FJTQsjRrJ9g1JWf4o+6B-BtWHbPA@mail.gmail.com>
On Wed, Oct 09, 2013 at 01:37:56PM -0700, Dylan Reid wrote:
> On Sun, Oct 6, 2013 at 8:48 PM, Vinod Koul <vinod.koul@intel.com> wrote:
> > On Mon, Oct 07, 2013 at 10:39:34AM +0900, Chanho Park wrote:
> >> > > Why didn't you use a cookie value to track the request?
> >> > > The cookie is assigned when each transfer is submitted.
> >> > > If you save the value in the desc, we can find the request easily.
> >> >
> >> > If there are several cyclic desc in the work list, is there a better way
> >> > to find the "current" one? The chan struct tracks the last completed and
> >> > last submitted cookies, but these will be the first and last
> >> > respectively as long as the cyclic transfer is active. Is there an
> >> > "active" cookie stored somewhere that I missed?
> >>
> >> Assume there are three cookies. If you want to get the second cookie not
> >> latest cookie, your way can be also correct in such case?
> >> I think tx_status API is to get dma status of the given cookie.
> >> You are only considering a cyclic case.
> > For cyclic case you would have possible same descriptor running till you
> > terminate.
>
> The cyclic case that makes this interesting is when there are multiple
> cyclic descriptors in the list. The cookie and completed_cookie
> markers don't help to determine which of the descriptors in the list
> is currently active. dma_cookie_complete isn't called for a cyclic
> desc, the desc is just pushed to the end of the list.
Yes the cyclic is a very different case. I think driver can still return for
cyclic case which was txstate->last and that will give clue to client which is
getting processed now!
> > For non cyclic, if you have 3 descriptors submitted, the cookie value can be, say
> > 7, 8 and 9. If you query the status of any descriptor and pass the last optional
> > txstate arg then you will know the last cookie completed. so if txstate->last is
> > 7, then 7th was completed and 8 should be running and 9 in queue!
>
> Got it, but the correct desc for cookie 8 will still have to be
> searched for, correct?
Yes
--
~Vinod
next prev parent reply other threads:[~2013-10-10 16:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-11 6:08 [PATCH 0/3] Add pl330 residue support Padmavathi Venna
2013-09-11 6:08 ` Padmavathi Venna
2013-09-11 6:08 ` [PATCH 1/3] dmaengine: pl330: Set residue in tx_status callback Padmavathi Venna
2013-09-11 6:08 ` Padmavathi Venna
2013-09-12 11:40 ` Chanho Park
2013-09-12 11:40 ` Chanho Park
2013-09-13 3:03 ` Padma Venkat
2013-09-13 3:03 ` Padma Venkat
2013-10-02 4:33 ` Dylan Reid
2013-10-02 4:33 ` Dylan Reid
2013-10-07 1:39 ` Chanho Park
2013-10-07 1:39 ` Chanho Park
2013-10-07 3:48 ` Vinod Koul
2013-10-07 3:48 ` Vinod Koul
2013-10-09 20:37 ` Dylan Reid
2013-10-09 20:37 ` Dylan Reid
2013-10-10 15:58 ` Vinod Koul [this message]
2013-10-10 15:58 ` Vinod Koul
2013-12-03 23:56 ` Alban Browaeys
2013-12-03 23:56 ` Alban Browaeys
2013-09-17 7:01 ` Vinod Koul
2013-09-17 7:01 ` Vinod Koul
2013-09-11 6:08 ` [PATCH 2/3] ARM: SAMSUNG: Add residue DMA operation Padmavathi Venna
2013-09-11 6:08 ` Padmavathi Venna
2013-09-11 6:08 ` [PATCH 3/3] ASoC: Update pointer to account for pending dma transfers Padmavathi Venna
2013-09-11 6:08 ` Padmavathi Venna
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