[{"id":3682323,"web_url":"http://patchwork.ozlabs.org/comment/3682323/","msgid":"<20260425185028.6023661e@jic23-huawei>","list_archive_url":null,"date":"2026-04-25T17:50:28","subject":"Re: [PATCH v8 3/6] iio: adc: ad4691: add triggered buffer support","submitter":{"id":10151,"url":"http://patchwork.ozlabs.org/api/people/10151/","name":"Jonathan Cameron","email":"jic23@kernel.org"},"content":"On Thu, 16 Apr 2026 12:18:48 +0300\nRadu Sabau via B4 Relay wrote:\n\n> From: Radu Sabau \n> \n> Add buffered capture support using the IIO triggered buffer framework.\n> \n> CNV Burst Mode: the GP pin identified by interrupt-names in the device\n> tree is configured as DATA_READY output. The IRQ handler stops\n> conversions and fires the IIO trigger; the trigger handler executes a\n> pre-built SPI message that reads all active channels from the AVG_IN\n> accumulator registers and then resets accumulator state and restarts\n> conversions for the next cycle.\n> \n> Manual Mode: CNV is tied to SPI CS so each transfer simultaneously\n> reads the previous result and starts the next conversion (pipelined\n> N+1 scheme). At preenable time a pre-built, optimised SPI message of\n> N+1 transfers is constructed (N channel reads plus one NOOP to drain\n> the pipeline). The trigger handler executes the message in a single\n> spi_sync() call and collects the results. An external trigger (e.g.\n> iio-trig-hrtimer) is required to drive the trigger at the desired\n> sample rate.\n> \n> Both modes share the same trigger handler and push a complete scan —\n> one u16 slot per channel at its scan_index position, followed by a\n> timestamp — to the IIO buffer via iio_push_to_buffers_with_ts().\n> \n> The CNV Burst Mode sampling frequency (PWM period) is exposed as a\n> buffer-level attribute via IIO_DEVICE_ATTR.\n> \n> Signed-off-by: Radu Sabau \nHi Radu,\n\nA couple of comments inline, but only for things to change\nif you end up doing a v9 for other reasons.\n\nthanks,\n\nJonathan\n\n> ---\n> drivers/iio/adc/Kconfig | 2 +\n> drivers/iio/adc/ad4691.c | 537 +++++++++++++++++++++++++++++++++++++++++++++--\n> 2 files changed, 524 insertions(+), 15 deletions(-)\n> \n> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig\n> index 3685a03aa8dc..d498f16c0816 100644\n> --- a/drivers/iio/adc/Kconfig\n> +++ b/drivers/iio/adc/Kconfig\n\n> @@ -84,19 +104,23 @@ enum ad4691_ref_ctrl {\n> \tAD4691_VREF_5P0 = 4,\n> };\n> \n> -struct ad4691_chip_info {\n> +struct ad4691_channel_info {\n> \tconst struct iio_chan_spec *channels;\n\nWe could mark this __counted_by_ptr() but that's new so no drivers\nare doing so yet. At somepoint I'll have a look at whether it's\nworth pushing it into existing drivers and if it is do this\none at that time. If you are respinning for other reasons though\nthen nice to have.\n\n> -\tconst char *name;\n> \tunsigned int num_channels;\n> +};\n> +\n> +struct ad4691_chip_info {\n> +\tconst char *name;\n> \tunsigned int max_rate;\n> +\tconst struct ad4691_channel_info *sw_info;\n> };\nI'm not going to ask you to respin just for this, but it would have\nbeen neater to push this factoring out of channels + num_channels\ninto the previous patch.","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pwm@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=FVxMT9NE;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; helo=sea.lore.kernel.org;\n envelope-from=linux-pwm+bounces-8691-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=\"FVxMT9NE\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=10.30.226.201"],"Received":["from sea.lore.kernel.org (sea.lore.kernel.org\n [IPv6:2600:3c0a:e001:db::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g2yN62hMrz1yHS\n\tfor ; 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