linux-kernel - Re: [PATCH] driver core: Make Kconfig text for DEBUG_TEST_DRIVER

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Date:   Mon, 31 Oct 2016 09:10:57 -0500
From:   Rob Herring <robh@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Laura Abbott <labbott@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH] driver core: Make Kconfig text for DEBUG_TEST_DRIVER_REMOVE
 stronger

On Mon, Oct 31, 2016 at 7:28 AM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> Hi Greg,
>
> On Mon, Oct 31, 2016 at 1:21 PM, Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
>> On Mon, Oct 31, 2016 at 11:12:45AM +0100, Geert Uytterhoeven wrote:
>>> On Fri, Oct 7, 2016 at 6:09 PM, Laura Abbott <labbott@...hat.com> wrote:
>>> > The current state of driver removal is not great.
>>> > CONFIG_DEBUG_TEST_DRIVER_REMOVE finds lots of errors. The help text
>>> > currently undersells exactly how many errors this option will find. Add
>>> > a bit more description to indicate this option shouldn't be turned on
>>> > unless you actually want to debug driver removal. The text can be
>>> > changed later when more drivers are fixed up.
>>>
>>> Indeed, this is failing miserably for e.g. SoC clock drivers using
>>> platform_driver_probe(), which are never retried, rendering the complete
>>> system useless.
>>
>> Why are they never retried?
>
> Because platform_driver_probe() is meant for non-hotpluggable devices,
> and unregisters the platform driver immediately if probe fails.
> See also the comments for __platform_driver_probe():

My patch "driver core: skip removal test for non-removable drivers"
fixes this case. It seems to have dropped from Greg's queue, so I'll
resend.

Rob