From: Jonathan Cameron <jic23@kernel.org>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Nuno Sa <Nuno.Sa@analog.com>
Subject: Re: [PATCH v2 11/16] iio: adc: max1027: Prevent single channel accesses during buffer reads
Date: Sun, 5 Sep 2021 16:38:04 +0100 [thread overview]
Message-ID: <20210905163804.67fca556@jic23-huawei> (raw)
In-Reply-To: <20210902211437.503623-12-miquel.raynal@bootlin.com>
On Thu, 2 Sep 2021 23:14:32 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> When hardware buffers are enabled (the cnvst pin being the trigger), one
> should not mess with the device state by requesting a single channel
> read.
>
> There is already a iio_buffer_enabled() check in *_read_single_value()
> to merely prevent this situation but the check is inconsistent since
> buffers can be enabled after the if clause anyway. Instead, use the core
> mutex by calling iio_device_claim/release_direct_mode().
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
> drivers/iio/adc/max1027.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> index f4cb5c75604b..57f62ea2d7aa 100644
> --- a/drivers/iio/adc/max1027.c
> +++ b/drivers/iio/adc/max1027.c
> @@ -296,10 +296,9 @@ static int max1027_read_single_value(struct iio_dev *indio_dev,
> int ret;
> struct max1027_state *st = iio_priv(indio_dev);
>
> - if (iio_buffer_enabled(indio_dev)) {
> - dev_warn(&indio_dev->dev, "trigger mode already enabled");
> - return -EBUSY;
> - }
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> + return ret;
>
> /* Configure conversion register with the requested chan */
> st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) |
> @@ -325,6 +324,8 @@ static int max1027_read_single_value(struct iio_dev *indio_dev,
> if (ret < 0)
> return ret;
Must also be released in error paths. Treat it like a lock (there is one
internally) so to avoid permanent deadlock we must release it even if things
are going wrong
>
> + iio_device_release_direct_mode(indio_dev);
> +
> *val = be16_to_cpu(st->buffer[0]);
>
> return IIO_VAL_INT;
next prev parent reply other threads:[~2021-09-05 15:34 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 21:14 [PATCH v2 00/16] Bring external triggers support to MAX1027-like ADCs Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 01/16] iio: adc: max1027: Fix style Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 02/16] iio: adc: max1027: Drop extra warning message Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 03/16] iio: adc: max1027: Drop useless debug messages Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 04/16] iio: adc: max1027: Avoid device managed allocators for DMA purposes Miquel Raynal
2021-09-05 15:26 ` Jonathan Cameron
2021-09-02 21:14 ` [PATCH v2 05/16] iio: adc: max1027: Minimize the number of converted channels Miquel Raynal
2021-09-05 15:34 ` Jonathan Cameron
2021-09-15 9:46 ` Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 06/16] iio: adc: max1027: Rename a helper Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 07/16] iio: adc: max1027: Create a helper to enable/disable the cnvst trigger Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 08/16] iio: adc: max1027: Simplify the _set_trigger_state() helper Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 09/16] iio: adc: max1027: Ensure a default cnvst trigger configuration Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 10/16] iio: adc: max1027: Create a helper to configure the channels to scan Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 11/16] iio: adc: max1027: Prevent single channel accesses during buffer reads Miquel Raynal
2021-09-05 15:38 ` Jonathan Cameron [this message]
2021-09-02 21:14 ` [PATCH v2 12/16] iio: adc: max1027: Separate the IRQ handler from the read logic Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 13/16] iio: adc: max1027: Introduce an end of conversion helper Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 14/16] iio: adc: max1027: Don't just sleep when the EOC interrupt is available Miquel Raynal
2021-09-06 9:38 ` Sa, Nuno
2021-09-15 9:55 ` Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 15/16] iio: adc: max1027: Add support for external triggers Miquel Raynal
2021-09-05 16:10 ` Jonathan Cameron
2021-09-06 9:53 ` Sa, Nuno
2021-09-15 15:45 ` Miquel Raynal
2021-09-18 17:39 ` Jonathan Cameron
2021-09-20 10:47 ` Miquel Raynal
2021-09-15 10:18 ` Miquel Raynal
2021-09-18 17:13 ` Jonathan Cameron
2021-09-20 8:37 ` Miquel Raynal
2021-09-20 17:43 ` Jonathan Cameron
2021-09-21 8:11 ` Miquel Raynal
2021-09-02 21:14 ` [PATCH v2 16/16] iio: adc: max1027: Don't reject external triggers when there is no IRQ Miquel Raynal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210905163804.67fca556@jic23-huawei \
--to=jic23@kernel.org \
--cc=Nuno.Sa@analog.com \
--cc=lars@metafoo.de \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=miquel.raynal@bootlin.com \
--cc=thomas.petazzoni@bootlin.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).