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Wed, 26 Mar 2025 09:26:01 -0400 From: Marcelo Schmitt To: , , CC: , , , , , Subject: [PATCH v3 4/4] Documentation: iio: ad4000: Describe offload support Date: Wed, 26 Mar 2025 10:25:57 -0300 Message-ID: <92b7db8eddce5b11476352405ed7695107ba7745.1742992305.git.marcelo.schmitt@analog.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-GUID: MoW91kgA5apYGZGc_Wz7L-ZCjARooGXc X-Proofpoint-ORIG-GUID: MoW91kgA5apYGZGc_Wz7L-ZCjARooGXc X-Authority-Analysis: v=2.4 cv=IuAecK/g c=1 sm=1 tr=0 ts=67e40074 cx=c_pps a=PpDZqlmH/M8setHirZLBMw==:117 a=PpDZqlmH/M8setHirZLBMw==:17 a=Vs1iUdzkB0EA:10 a=wI1k2SEZAAAA:8 a=gAnH3GRIAAAA:8 a=zhJGIpXlanaEhhhmQREA:9 a=6HWbV-4b7c7AdzY24d_u:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-26_06,2025-03-26_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 impostorscore=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 phishscore=0 spamscore=0 adultscore=0 bulkscore=0 mlxlogscore=999 mlxscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503260082 Content-Type: text/plain; charset="utf-8" When SPI offloading is supported, the IIO device provides different sysfs interfaces to allow using the adjusting the sample rate. Document SPI offload support for AD4000 and similar devices. Signed-off-by: Marcelo Schmitt Reviewed-by: David Lechner --- Documentation/iio/ad4000.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/Documentation/iio/ad4000.rst b/Documentation/iio/ad4000.rst index 468d30dc9214..e490f9604b94 100644 --- a/Documentation/iio/ad4000.rst +++ b/Documentation/iio/ad4000.rst @@ -191,3 +191,25 @@ Typical voltage channel attributes of a differential A= D4000 series device: +-------------------------------------------+-----------------------------= -------------+ | ``in_voltage0-voltage1_scale_available`` | Toggles input span compressi= on | +-------------------------------------------+-----------------------------= -------------+ + +SPI offload support +------------------- + +To be able to achieve the maximum sample rate, the driver can be used with= the +`AXI SPI Engine`_ to provide SPI offload support. + +.. _AXI SPI Engine: http://analogdevicesinc.github.io/hdl/projects/pulsar_= adc/index.html + +When set for SPI offload support, the IIO device will provide different +interfaces. + +* Either ``in_voltage0_sampling_frequency`` or + ``in_voltage0-voltage1_sampling_frequency`` file is provided to allow se= tting + the sample rate. +* IIO trigger device is not provided (no ``trigger`` directory). +* ``timestamp`` channel is not provided. + +Also, because the ADC output has a one sample latency (delay) when the dev= ice is +wired in "3-wire" mode and only one transfer per sample is done when using= SPI +offloading, the first data sample in the buffer is not valid because it co= ntains +the output of an earlier conversion result. --=20 2.47.2