From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A3AD24A055; Tue, 29 Apr 2025 17:04:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745946244; cv=none; b=RHCaOiw/9etawQFkY7lO6ylXKcEhwn8wLU1X/uOwCGXcvOcYqC0AfbgSHiUGTAo6SJLsxMuPGDJRxiAw1LTQNFVo8BSb/tsuiyNSZ0SaAtfHY0X6sTyECEmcFwPxF5LpXZxEXd98tquuDIypeJWXGinyb0h5Vc0L97umqjLuQZY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745946244; c=relaxed/simple; bh=eqKTnQ+1K+uwuRq/RP58NB/AH7hmIKolqRnCq4UfCbs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LzRfdDogW9U1tppsL+7IMiBYfNsy2K5ntuxnUdrWPigu4C4P6cuR8nWXzaF/gzYyeMVcV/mB+pMDAAHAE4EhKKnD5/2DDQD6lg8lsnW8YD92YBoNZquR9jkVr8u95V08Q2ENabvKOa8bQ/hlql+9QH4VoVU7dfK0eFJ8y4f9IQY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WQFhwj7B; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WQFhwj7B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 531EDC4CEE3; Tue, 29 Apr 2025 17:04:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745946243; bh=eqKTnQ+1K+uwuRq/RP58NB/AH7hmIKolqRnCq4UfCbs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WQFhwj7BPpSihe72qiBw2RRJ2DrthC4t3m6e0Ml7R3fnOmVY3H3kuuI6hbeXtHiZh 2fPs7avkrUmtizQdEfJ/5gq4qjfQ5XWYHC3gse+jfPBu+ZrMydXoel8FkaNj+SY8CU akLYQ7L+P26c2i6ft8SwQoRi0lQUPxpGvNBVXPP0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Trevor Gamblin , David Lechner , Jonathan Cameron , Sasha Levin Subject: [PATCH 6.14 202/311] iio: adc: ad4695: make ad4695_exit_conversion_mode() more robust Date: Tue, 29 Apr 2025 18:40:39 +0200 Message-ID: <20250429161129.286427437@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161121.011111832@linuxfoundation.org> References: <20250429161121.011111832@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Trevor Gamblin [ Upstream commit 998d20e4e99d909f14d96fdf0bdcf860f7efe3ef ] Ensure that conversion mode is successfully exited when the command is issued by adding an extra transfer beforehand, matching the minimum CNV high and low times from the AD4695 datasheet. The AD4695 has a quirk where the exit command only works during a conversion, so guarantee this happens by triggering a conversion in ad4695_exit_conversion_mode(). Then make this even more robust by ensuring that the exit command is run at AD4695_REG_ACCESS_SCLK_HZ rather than the bus maximum. Signed-off-by: Trevor Gamblin Reviewed-by: David Lechner Tested-by: David Lechner Link: https://patch.msgid.link/20241113-tgamblin-ad4695_improvements-v2-2-b6bb7c758fc4@baylibre.com Signed-off-by: Jonathan Cameron Signed-off-by: Sasha Levin --- drivers/iio/adc/ad4695.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c index b79d135a54718..22fdc454b0cea 100644 --- a/drivers/iio/adc/ad4695.c +++ b/drivers/iio/adc/ad4695.c @@ -92,6 +92,8 @@ #define AD4695_T_REFBUF_MS 100 #define AD4695_T_REGCONFIG_NS 20 #define AD4695_T_SCK_CNV_DELAY_NS 80 +#define AD4695_T_CNVL_NS 80 +#define AD4695_T_CNVH_NS 10 #define AD4695_REG_ACCESS_SCLK_HZ (10 * MEGA) /* Max number of voltage input channels. */ @@ -364,11 +366,31 @@ static int ad4695_enter_advanced_sequencer_mode(struct ad4695_state *st, u32 n) */ static int ad4695_exit_conversion_mode(struct ad4695_state *st) { - struct spi_transfer xfer = { - .tx_buf = &st->cnv_cmd2, - .len = 1, - .delay.value = AD4695_T_REGCONFIG_NS, - .delay.unit = SPI_DELAY_UNIT_NSECS, + /* + * An extra transfer is needed to trigger a conversion here so + * that we can be 100% sure the command will be processed by the + * ADC, rather than relying on it to be in the correct state + * when this function is called (this chip has a quirk where the + * command only works when reading a conversion, and if the + * previous conversion was already read then it won't work). The + * actual conversion command is then run at the slower + * AD4695_REG_ACCESS_SCLK_HZ speed to guarantee this works. + */ + struct spi_transfer xfers[] = { + { + .delay.value = AD4695_T_CNVL_NS, + .delay.unit = SPI_DELAY_UNIT_NSECS, + .cs_change = 1, + .cs_change_delay.value = AD4695_T_CNVH_NS, + .cs_change_delay.unit = SPI_DELAY_UNIT_NSECS, + }, + { + .speed_hz = AD4695_REG_ACCESS_SCLK_HZ, + .tx_buf = &st->cnv_cmd2, + .len = 1, + .delay.value = AD4695_T_REGCONFIG_NS, + .delay.unit = SPI_DELAY_UNIT_NSECS, + }, }; /* @@ -377,7 +399,7 @@ static int ad4695_exit_conversion_mode(struct ad4695_state *st) */ st->cnv_cmd2 = AD4695_CMD_EXIT_CNV_MODE << 3; - return spi_sync_transfer(st->spi, &xfer, 1); + return spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers)); } static int ad4695_set_ref_voltage(struct ad4695_state *st, int vref_mv) -- 2.39.5