Date: Mon, 22 Dec 2014 20:02:33 +0100
From: Wolfram Sang <wsa@the-dreams.de>
To: Walter Lozano <walter@vanguardiasur.com.ar>
Cc: mika.westerberg@linux.intel.com, Romain.Baeriswyl@abilis.com,
        atull@opensource.altera.com, raymond.tan@intel.com,
        carlpeng008@gmail.com, linux-i2c@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC] i2c: designware: Avoid initcall and initialize the driver
 like a regular one
Message-ID: <20141222190233.GA1014@katana>
References: <1419272149-28716-1-git-send-email-walter@vanguardiasur.com.ar>
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On Mon, Dec 22, 2014 at 03:15:49PM -0300, Walter Lozano wrote:
> Currently, the driver is relying on a subsys_initcall() to register
> the platform driver struct. This is typically done to allow early uses
> of the I2C bus (for instance, I2C regulators used from early machine code=
).
>=20
> While this might work on some cases, it breaks on others. For instance,
> I2C devices with GPIO-wired interrupts will fail to request the
> interrupt because of this initcall usage.
>=20
> This commits attempts to fix the above issue, by converting the I2C
> driver into a regular kernel platform driver. This guarantees it will
> probe after GPIOs drivers.
>=20
> Platforms based on devicetree won't be affected by this change.

Huh, why is that?

> Legacy platforms, relying on the I2C being available early, might need
> to implement proper defered mechanisms to overcome potential problems.

NAK. We can't say "Let's cause a regression to force people to fix
things that used to work" IMO. You exactly pointed out the problem that usi=
ng
subsys_initcall() creates.

What about fixing the drivers you use to support deferred probing when
acquitin the irq?

Regards,

   Wolfram

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