| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <aRsSkGLO2ELzgca_@pengutronix.de>
Date: Mon, 17 Nov 2025 13:18:24 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
David Jander <david@...tonic.nl>, kernel@...gutronix.de,
linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, Andy Shevchenko <andy@...nel.org>,
David Lechner <dlechner@...libre.com>,
Nuno Sá <nuno.sa@...log.com>
Subject: Re: [PATCH v3 2/2] iio: adc: Add TI ADS131M0x ADC driver
On Fri, Nov 14, 2025 at 08:24:23PM +0200, Andy Shevchenko wrote:
> On Fri, Nov 14, 2025 at 11:20 AM Oleksij Rempel <o.rempel@...gutronix.de> wrote:
> > +config TI_ADS131M02
> > + tristate "Texas Instruments ADS131M02"
> > + depends on SPI && COMMON_CLK && REGULATOR
>
> Hmm... The COMMON_CLK looks strange here. Why?
I can drop it, but the driver will fail without proper clock
configuration anyways.
> > + select CRC_ITU_T
>
> Btw, why does it not use regmap?
I already answered it here:
https://lore.kernel.org/all/aQ3J_rJV-hB2nh91@pengutronix.de/
> > +#include <linux/array_size.h>
> > +#include <linux/bitfield.h>
> > +#include <linux/bitops.h>
> > +#include <linux/cleanup.h>
> > +#include <linux/clk.h>
> > +#include <linux/crc-itu-t.h>
> > +#include <linux/delay.h>
> > +#include <linux/dev_printk.h>
>
> > +#include <linux/device.h>
>
> Is it used? I haven't found what API or data structure is required from here.
>
> > +#include <linux/device/devres.h>
> > +#include <linux/err.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/lockdep.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/string.h>
> > +#include <linux/types.h>
> > +#include <linux/unaligned.h>
>
> ...
>
> > +#define ADS131M_CMD_RREG_OP 0xa000
> > +#define ADS131M_CMD_WREG_OP 0x6000
>
> These two have bit 13 always set. What is the meaning of that bit?
Dokumentation do not provides this information.
>
> > +#define ADS131M_CMD_RREG(a, n) \
> > + (ADS131M_CMD_RREG_OP | \
> > + FIELD_PREP(ADS131M_CMD_ADDR_MASK, a) | \
> > + FIELD_PREP(ADS131M_CMD_NUM_MASK, n))
> > +#define ADS131M_CMD_WREG(a, n) \
> > + (ADS131M_CMD_WREG_OP | \
> > + FIELD_PREP(ADS131M_CMD_ADDR_MASK, a) | \
> > + FIELD_PREP(ADS131M_CMD_NUM_MASK, n))
>
> ...
>
> > +/**
> > + * ads131m_tx_frame_unlocked - Sends a command frame with Input CRC
> > + * @priv: Device private data structure.
> > + * @command: The 16-bit command to send (e.g., NULL, RREG, RESET).
> > + *
> > + * This function sends a command in Word 0, and its calculated 16-bit
> > + * CRC in Word 1, as required when Input CRC is enabled.
> > + *
> > + * Return: 0 on success, or a negative error code from spi_sync.
>
> spi_sync()
>
> But I would drop it as it makes dependency on the code changes and it
> will deviate easily if code grows and something else becomes a call
> that returns an error, also this simply doesn't scale: are you going
> to list whole bunch of APIs in the kernel doc? (rhetorical Q) Ditto
> for other similar cases.
ack
> > +static int ads131m_hw_reset(struct ads131m_priv *priv)
> > + ret = gpiod_set_value_cansleep(priv->reset_gpio, 0);
> > + if (ret < 0)
> > + return dev_err_probe(dev, ret, "Failed to deassert reset GPIO\n");
> > +
> > + /* Wait t_REGACQ (5us) for registers to be accessible */
> > + fsleep(ADS131M_RESET_DELAY_US);
> > +
> > + return 0;
> > +}
>
> Can you use the reset-gpio driver instead of a custom approach?
I do not have strong option about this right now.
> ...
>
> > + /*
> > + * Get the optional external reference. This schedules regulator_put()
> > + * automatically.
> > + */
> > + priv->refin_supply = devm_regulator_get_optional(dev, "refin");
> > + ret = PTR_ERR_OR_ZERO(priv->refin_supply);
> > + if (ret == -ENODEV)
> > + priv->refin_supply = NULL;
> > + else if (ret < 0)
> > + return dev_err_probe(dev, ret, "failed to get refin regulator\n");
>
> So, will the refin_supply be ever an error pointer? I think no, hence
> why IS_ERR_OR_NULL() in the user somewhere above in the code?
Looks like error pointer:
https://elixir.bootlin.com/linux/v6.18-rc5/source/include/linux/regulator/consumer.h#L351
> > +static int ads131m_parse_clock(struct ads131m_priv *priv, bool *is_xtal)
> > +{
> > + struct device *dev = &priv->spi->dev;
> > + int ret;
> > +
> > + priv->clk = devm_clk_get_enabled(dev, NULL);
> > + if (IS_ERR(priv->clk))
> > + return dev_err_probe(dev, PTR_ERR(priv->clk), "clk get enabled failed\n");
> > +
> > + ret = device_property_match_string(dev, "clock-names", "xtal");
> > + if (ret == 0) {
> > + if (!priv->config->supports_xtal)
> > + return dev_err_probe(dev, -EINVAL,
> > + "'xtal' clock not supported on this device");
>
> > + *is_xtal = true;
> > +
> > + return 0;
>
> This...
>
> > + } else if (ret > 0) {
> > + return dev_err_probe(dev, -EINVAL, "'xtal' must be the only or first clock name");
>
> > + } else if (ret == -ENODATA) {
> > + *is_xtal = false;
> > +
> > + return 0;
> > + }
> > +
> > + return dev_err_probe(dev, ret, "failed to read 'clock-names' property");
>
> ...and this can be deduplicated, so the first one becomes just a check
> for !supports_xtal.
>
> if (ret == 0) && !supports_xtal)
> return dev_err_probe(...);
> else if (ret > 0)
> return dev_err_probe(...);
>
> This one will be modified to
>
> else if (ret != -ENODATA)
> return dev_err_probe(...);
>
> *is_xtal = !ret;
> return ret;
ok.
> > +}
>
> ...
>
> > + config = spi_get_device_match_data(spi);
>
> > + if (!config)
> > + return dev_err_probe(dev, -EINVAL, "No device configuration data found\n");
>
> Without this code will crash, right? So, I consider this check is
> redundant because any support of any new chip requires this, and if
> one didn't add the driver data, means it wasn't tested (which is a
> good trap on itself during code review).
ok.
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Powered by blists - more mailing lists