From: Lars-Peter Clausen <lars@metafoo.de>
To: Jonathan Cameron <jic23@kernel.org>,
Alexandru Ardelean <ardeleanalex@gmail.com>
Cc: Hartmut Knaack <knaack.h@gmx.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
Alexandru Ardelean <alexandru.ardelean@analog.com>,
linux-iio <linux-iio@vger.kernel.org>
Subject: Re: [PATCH] iio: buffer-dmaengine: adjust `bytes_used` with residue info
Date: Sat, 29 Aug 2020 20:30:04 +0200 [thread overview]
Message-ID: <f336acac-ed70-ad88-57ca-8d06ec54182e@metafoo.de> (raw)
In-Reply-To: <20200829165134.3361315a@archlinux>
On 8/29/20 5:51 PM, Jonathan Cameron wrote:
> On Wed, 26 Aug 2020 09:36:39 +0300
> Alexandru Ardelean <ardeleanalex@gmail.com> wrote:
>
>> On Wed, Aug 26, 2020 at 8:22 AM Lars-Peter Clausen <lars@metafoo.de> wrote:
>>> From: Alexandru Ardelean <alexandru.ardelean@analog.com>
>>>
>>> A transfer may fall shorter than the bytes in the block.
>>> This information is available in the residue from the DMA engine, so we can
>>> compute actual `bytes_used` with that by subtracting the residue.
>>>
>> This was in my pipeline as well [obviously].
>> Thanks :)
>>
>>> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
>>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> "smells" like a fix. Is it? Or are we looking at something that
> only matters for some future hardware, or an optmization?
>
> If it's a fix, where is the fixes tag?
It's a feature :)
When we first added the IIO DMA buffer support this API did not exist in
dmaengine. So for the longest time most DMA drivers did not have the
ability to report short transfers. Primarily because in many cases the
hardware doesn't even support it.
Now with this patch the IIO DMA buffer implementation supports systems
where the DMA can generate short transfers.
- Lars
next prev parent reply other threads:[~2020-08-29 18:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-26 5:20 [PATCH] iio: buffer-dmaengine: adjust `bytes_used` with residue info Lars-Peter Clausen
2020-08-26 6:36 ` Alexandru Ardelean
2020-08-29 15:51 ` Jonathan Cameron
2020-08-29 18:30 ` Lars-Peter Clausen [this message]
2020-08-30 11:10 ` Jonathan Cameron
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