linux-kernel - Re: [PATCH v4 4/7] i2c: core: Make i2c_acpi_get_irq available to the rest of the I2C core

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Message-ID: <20190613084858.GU28362@ediswmail.ad.cirrus.com>
Date:   Thu, 13 Jun 2019 09:48:58 +0100
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     <wsa@...-dreams.de>, <jarkko.nikula@...ux.intel.com>,
        <andriy.shevchenko@...ux.intel.com>, <linux-i2c@...r.kernel.org>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <benjamin.tissoires@...hat.com>, <jbroadus@...il.com>,
        <patches@...nsource.cirrus.com>
Subject: Re: [PATCH v4 4/7] i2c: core: Make i2c_acpi_get_irq available to the
 rest of the I2C core

On Wed, Jun 12, 2019 at 06:27:18PM +0300, Mika Westerberg wrote:
> On Tue, Jun 11, 2019 at 01:30:58PM +0100, Charles Keepax wrote:
> > In preparation for more refactoring make i2c_acpi_get_irq available
> > outside i2c-core-acpi.c.
> > 
> > Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
> > ---
> > 
> > Changes since v3:
> >  - Move the change to use the helper function from i2c-core-base into its own patch.
> > 
> > Thanks,
> > Charles
> > 
> >  drivers/i2c/i2c-core-acpi.c | 15 +++++++++++++--
> >  drivers/i2c/i2c-core.h      |  7 +++++++
> >  2 files changed, 20 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> > index 7d4d66ba752d4..35966cc337dde 100644
> > --- a/drivers/i2c/i2c-core-acpi.c
> > +++ b/drivers/i2c/i2c-core-acpi.c
> > @@ -144,8 +144,17 @@ static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
> >  	return 1; /* No need to add resource to the list */
> >  }
> >  
> > -static int i2c_acpi_get_irq(struct acpi_device *adev)
> > +/**
> > + * i2c_acpi_get_irq - get device IRQ number from ACPI
> > + * @client: Pointer to the I2C client device
> > + *
> > + * Find the IRQ number used by a specific client device.
> > + *
> > + * Return: The IRQ number or an error code.
> > + */
> > +int i2c_acpi_get_irq(struct i2c_client *client)
> >  {
> > +	struct acpi_device *adev = ACPI_COMPANION(&client->adapter->dev);
> 
> Is this adev checked for being NULL somewhere below before it is being
> dereferenced?
> 
> It could explain the issue Benjamin is seeing.
> 

Yeah could be that or just for some reason this isn't returning
the same adev as we previously had. I will do some digging see if
I can find any likely culprits.

Thanks,
Charles