From: "Sa, Nuno" <Nuno.Sa@analog.com>
To: Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
Jonathan Cameron <jic23@kernel.org>
Cc: "Hennerich, Michael" <Michael.Hennerich@analog.com>,
"zzzzArdelean, zzzzAlexandru" <alexandru.Ardelean@analog.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"lars@metafoo.de" <lars@metafoo.de>,
"Bogdan, Dragos" <Dragos.Bogdan@analog.com>
Subject: RE: [PATCH v3 0/6] iio: Add output buffer support
Date: Mon, 8 Mar 2021 13:00:37 +0000 [thread overview]
Message-ID: <CY4PR03MB26318FE58CDB5301224EAC9399939@CY4PR03MB2631.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20210308115203.00006230@Huawei.com>
> -----Original Message-----
> From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> Sent: Monday, March 8, 2021 12:52 PM
> To: Sa, Nuno <Nuno.Sa@analog.com>; Jonathan Cameron
> <jic23@kernel.org>
> Cc: Hennerich, Michael <Michael.Hennerich@analog.com>;
> zzzzArdelean, zzzzAlexandru <alexandru.Ardelean@analog.com>;
> linux-kernel@vger.kernel.org; linux-iio@vger.kernel.org;
> lars@metafoo.de; Bogdan, Dragos <Dragos.Bogdan@analog.com>
> Subject: Re: [PATCH v3 0/6] iio: Add output buffer support
>
> [External]
>
> On Mon, 8 Mar 2021 10:07:05 +0000
> "Sa, Nuno" <Nuno.Sa@analog.com> wrote:
>
> > > -----Original Message-----
> > > From: Jonathan Cameron <jic23@kernel.org>
> > > Sent: Saturday, March 6, 2021 6:35 PM
> > > To: Hennerich, Michael <Michael.Hennerich@analog.com>
> > > Cc: zzzzArdelean, zzzzAlexandru
> <alexandru.Ardelean@analog.com>;
> > > linux-kernel@vger.kernel.org; linux-iio@vger.kernel.org;
> > > lars@metafoo.de; Sa, Nuno <Nuno.Sa@analog.com>; Bogdan,
> Dragos
> > > <Dragos.Bogdan@analog.com>
> > > Subject: Re: [PATCH v3 0/6] iio: Add output buffer support
> > >
> > > On Fri, 5 Mar 2021 08:57:08 +0000
> > > "Hennerich, Michael" <Michael.Hennerich@analog.com> wrote:
> > >
> > > > Hi Jonathan and others,
> > > >
> > > > With output/dac buffer support the semantics of the
> scan_element
> > > type may change.
> > > >
> > > > Today the Format is
> [be|le]:[s|u]bits/storagebitsXrepeat[>>shift].
> > > >
> > > > While shift (if specified) is the shift that needs to be applied prior
> to
> > > masking out unused bits.
> > > >
> > > > So far so good and it sounds universal.
> > > >
> > > > However, we use the right shift (operator) for that, which makes
> > > sense for capture devices.
> > > > For output devices the more logical operator would be the left
> shift.
> > > >
> > > > I'm not proposing a new Format here. I just want to get some
> > > agreement that for an output device
> > > >
> > > > le:s12/16>>4
> > > >
> > > > is understood as a left shift of 4, since the unused bits are then
> on
> > > the LSB.
> > >
> > > Good question. Guess I wasn't thinking ahead when I came up with
> > > that :)
> > >
> > > I'm not sure I'd mind if we did decide to define a new format for
> > > output
> > > buffers. Feels like it should be easy to do.
> > >
> > > What do others think?
> > >
> >
> > I guess the most straight forward thing would be just to add a 'shift_l'
> variable
> > to 'struct scan_type'' and make sure either 'shift_l' or 'shift' is defined
> and then
> > properly export either ">>" or "<<" to userspace?
>
> Given we already know it's an output channel, can we not just use that
> to make the decision?
>
> Jonathan
I would argue that having two variables gives us more flexibility for whatever
the future brings us :). But if we can sanely say that an output buffer will
always use left shifts, then we could definitely use that information... I mean,
we are already doing that assumption for input buffers and right shifts...
- Nuno Sá
next prev parent reply other threads:[~2021-03-08 13:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 12:40 [PATCH v3 0/6] iio: Add output buffer support Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 1/6] " Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 2/6] iio: kfifo-buffer: " Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 3/6] iio: triggered-buffer: extend support to configure output buffers Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 4/6] iio: buffer-dma: Allow to provide custom buffer ops Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 5/6] iio: buffer-dma: Add output buffer support Alexandru Ardelean
2021-02-19 12:40 ` [PATCH v3 6/6] iio: buffer-dma: add support for cyclic DMA transfers Alexandru Ardelean
2021-02-21 12:09 ` Jonathan Cameron
2021-02-23 6:34 ` Alexandru Ardelean
2021-02-21 12:01 ` [PATCH v3 0/6] iio: Add output buffer support Jonathan Cameron
2021-03-05 8:57 ` Hennerich, Michael
2021-03-06 17:34 ` Jonathan Cameron
2021-03-08 10:07 ` Sa, Nuno
2021-03-08 11:52 ` Jonathan Cameron
2021-03-08 13:00 ` Sa, Nuno [this message]
2021-03-08 13:17 ` Sa, Nuno
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