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Date: Sat, 26 Oct 2024 16:51:47 +0100
From: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <dlechner@baylibre.com>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh@kernel.org>,
 Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley
 <conor+dt@kernel.org>, Nuno =?UTF-8?B?U8Oh?= <nuno.sa@analog.com>, Uwe
 =?UTF-8?B?S2xlaW5lLUvDtm5pZw==?= <ukleinek@kernel.org>, Michael Hennerich
 <Michael.Hennerich@analog.com>, Lars-Peter Clausen <lars@metafoo.de>, David
 Jander <david@protonic.nl>, Martin Sperl <kernel@martin.sperl.org>,
 linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org,
 linux-pwm@vger.kernel.org
Subject: Re: [PATCH RFC v4 13/15] iio: adc: ad7944: add support for SPI
 offload
Message-ID: <20241026165147.2d67d160@jic23-huawei>
In-Reply-To: <20241023-dlech-mainline-spi-engine-offload-2-v4-13-f8125b99f5a1@baylibre.com>
References: <20241023-dlech-mainline-spi-engine-offload-2-v4-0-f8125b99f5a1@baylibre.com>
	<20241023-dlech-mainline-spi-engine-offload-2-v4-13-f8125b99f5a1@baylibre.com>
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On Wed, 23 Oct 2024 15:59:20 -0500
David Lechner <dlechner@baylibre.com> wrote:

> This adds support for SPI offload to the ad7944 driver. This allows
> reading data at the max sample rate of 2.5 MSPS.
> 
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
>
>  static int ad7944_probe(struct spi_device *spi)
>  {
>  	const struct ad7944_chip_info *chip_info;
> @@ -590,20 +743,75 @@ static int ad7944_probe(struct spi_device *spi)
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &ad7944_iio_info;
>  
> -	if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) {
> -		indio_dev->available_scan_masks = chain_scan_masks;
> -		indio_dev->channels = chain_chan;
> -		indio_dev->num_channels = n_chain_dev + 1;
> +	adc->offload = devm_spi_offload_get(dev, spi, &ad7944_offload_config);
> +	ret = PTR_ERR_OR_ZERO(adc->offload);
> +	if (ret && ret != -ENODEV)
> +		return dev_err_probe(dev, ret, "failed to get offload\n");
> +
> +	if (ret == -ENODEV) {
> +		dev_info(dev, "SPI offload not available\n");
Too noisy given this applies whenever this device is connected to a normal
SPI bus.  Or an old DT is used.

> +
>
>