From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Jan Dabros <jsd@semihalf.com>, Andi Shyti <andi.shyti@kernel.org>,
Lixu Zhang <lixu.zhang@intel.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Binbin Zhou <zhoubinbin@loongson.cn>,
Fabrizio Castro <fabrizio.castro.jz@renesas.com>,
Israel Cepeda <israel.a.cepeda.lopez@intel.com>,
Hans de Goede <hansg@kernel.org>,
Bartosz Golaszewski <brgl@kernel.org>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH 0/7] i2c: provide and use i2c_adapter_set_node()
Date: Sat, 27 Dec 2025 16:33:44 +0200 [thread overview]
Message-ID: <aU_uSLpDh2FCvAFo@smile.fi.intel.com> (raw)
In-Reply-To: <20251223-i2c-ada-dev-set-node-v1-0-2e36e0e785b4@oss.qualcomm.com>
On Tue, Dec 23, 2025 at 11:06:47AM +0100, Bartosz Golaszewski wrote:
> It's been another year of discussing the object life-time problems at
> conferences. I2C is one of the offenders and its problems are more
> complex than those of some other subsystems. It seems the revocable[1]
> API may make its way into the kernel this year but even with it in
> place, I2C won't be able to use it as there's currently nothing to
> *revoke*. The struct device is embedded within the i2c_adapter struct
> whose lifetime is tied to the provider device being bound to its driver.
>
> Fixing this won't be fast and easy but nothing's going to happen if we
> don't start chipping away at it. The ultimate goal in order to be able
> to use an SRCU-based solution (revocable or otherwise) is to convert the
> embedded struct device in struct i2c_adapter into an __rcu pointer that
> can be *revoked*. To that end we need to hide all dereferences of
> adap->dev in drivers.
>
> I2C drivers use device_set_node() to assign a firmware node directly to
> the struct device embedded in i2c_adapter. In order to hide the direct
> dereferencing: provide a dedicated interface that wraps the call to
> device_set_node() but takes the adapter as argument instead.
> [1] https://lore.kernel.org/all/20251106152330.11733-1-tzungbi@kernel.org/
Can be also made as a Link tag and some people use `b4 shazam`, that uses the
above test as a merge commit message where other tags are also being
recognized.
Have no objection and code looks good,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
--
With Best Regards,
Andy Shevchenko
prev parent reply other threads:[~2025-12-27 14:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-23 10:06 [PATCH 0/7] i2c: provide and use i2c_adapter_set_node() Bartosz Golaszewski
2025-12-23 10:06 ` [PATCH 1/7] i2c: provide i2c_adapter_set_node() Bartosz Golaszewski
2025-12-23 10:06 ` [PATCH 2/7] i2c: designware-common: use i2c_adapter_set_node() Bartosz Golaszewski
2025-12-30 10:29 ` Mika Westerberg
2025-12-23 10:06 ` [PATCH 3/7] i2c: gpio: " Bartosz Golaszewski
2026-01-15 18:28 ` Wolfram Sang
2026-01-16 11:31 ` Bartosz Golaszewski
2025-12-23 10:06 ` [PATCH 4/7] i2c: ljca: " Bartosz Golaszewski
2025-12-30 0:40 ` Zhang, Lixu
2025-12-30 10:03 ` Sakari Ailus
2025-12-23 10:06 ` [PATCH 5/7] i2c: ls2x: " Bartosz Golaszewski
2025-12-30 10:39 ` Binbin Zhou
2025-12-23 10:06 ` [PATCH 6/7] i2c: rzv2m: " Bartosz Golaszewski
2026-01-05 9:14 ` Fabrizio Castro
2025-12-23 10:06 ` [PATCH 7/7] i2c: usbio: " Bartosz Golaszewski
2025-12-30 10:04 ` Sakari Ailus
2025-12-27 14:33 ` Andy Shevchenko [this message]
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