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[2003:f6:ef1c:c500:994e:fbde:478:1ce1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42caf33e9b2sm102001305e9.14.2024.09.10.01.08.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Sep 2024 01:08:28 -0700 (PDT) Message-ID: Subject: Re: [PATCH v2 1/9] dt-bindings: iio: dac: ad3552r: add io-backend property From: Nuno =?ISO-8859-1?Q?S=E1?= To: Conor Dooley Cc: Conor Dooley , Jonathan Cameron , Angelo Dureghello , Lars-Peter Clausen , Michael Hennerich , Nuno =?ISO-8859-1?Q?S=E1?= , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Olivier Moysan , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, David Lechner Date: Tue, 10 Sep 2024 10:12:36 +0200 In-Reply-To: <20240909-retrieval-guide-da2a35e571a5@spud> References: <20240905-wip-bl-ad3552r-axi-v0-iio-testing-v2-0-87d669674c00@baylibre.com> <20240905-wip-bl-ad3552r-axi-v0-iio-testing-v2-1-87d669674c00@baylibre.com> <20240908132925.331c5175@jic23-huawei> <20240909-dwelled-specimen-949f44c8d04d@wendy> <1dca9ce52e7c701c7fb6cbbc723e9dff5d0ace8b.camel@gmail.com> <20240909-retrieval-guide-da2a35e571a5@spud> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.4 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2024-09-09 at 17:06 +0100, Conor Dooley wrote: > On Mon, Sep 09, 2024 at 04:03:17PM +0200, Nuno S=C3=A1 wrote: > > On Mon, 2024-09-09 at 13:46 +0100, Conor Dooley wrote: > > > On Sun, Sep 08, 2024 at 01:29:25PM +0100, Jonathan Cameron wrote: >=20 > > > I'd also really like to know how this fits in with spi-offloads. It > > > /feels/, and I'd like to reiterate the word feels, like a rather simi= lar > > > idea just applied to a DAC instead of an ADC. > >=20 > > The offload main principle is to replay a spi transfer periodically giv= en an > > input trigger. I'm not so sure we have that same principle in here. In = here > > I > > guess we stream data over the qspi interface based on SCLK which can lo= ok > > similar. The difference is that this IP does not need any trigger for a= ny > > spi > > transfer replay (I think).=20 >=20 > Right, if the trigger part is what decides it for you then I'm wildin > here. I mean, not only the trigger. These IPs (axi-dac/adc) are meant to deal wit= h data while in theory the spi offload principle is about replaying any spi transfers. But yeah, the above reasoning does not make sense as a data tran= sfer is still a transfer. FWIW, these IPs are inherently offload HW as their goal is really to stream= data without any SW intervention (so called HW_BUFFERING in IIO world). Just tha= t typically you have LVDS/CMOS data interfaces and now we have a qspi interfa= ce and a spi-offload concept already introduced.=C2=A0 So, yeah, as we want to have spi-offloads documented in the bindings, we ca= n also document this setup with the same bindings. - Nuno S=C3=A1