From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: [PATCH] iio: accel: bmc150: Add OF device ID table Date: Mon, 4 Dec 2017 11:24:40 +0100 Message-ID: <337e54d5-7248-9eb2-e0c0-3a8b5443723d@redhat.com> References: <20171201111058.13483-1-javierm@redhat.com> <313108f3-2815-b030-4fa6-614efc31a8a9@redhat.com> <20171204092259.00006250@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171204092259.00006250-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Content-Language: en-US Sender: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jonathan Cameron , Hans de Goede Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Hartmut Knaack , linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Lars-Peter Clausen , Jonathan Cameron , Peter Meerwald-Stadler , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wolfram Sang List-Id: devicetree@vger.kernel.org Hello Jonathan, On 12/04/2017 10:44 AM, Jonathan Cameron wrote: > On Mon, 4 Dec 2017 09:29:38 +0100 > Hans de Goede wrote: > >> Hi, >> >> On 01-12-17 12:10, Javier Martinez Canillas wrote: >>> The driver doesn't have a struct of_device_id table but supported devices >>> are registered via Device Trees. This is working on the assumption that a >>> I2C device registered via OF will always match a legacy I2C device ID and >>> that the MODALIAS reported will always be of the form i2c:. >>> >>> But this could change in the future so the correct approach is to have an >>> OF device ID table if the devices are registered via OF. >>> >>> The I2C device ID table entries have the .driver_data field set, but they >>> are not used in the driver so weren't set in the OF device table entries. >>> >>> Signed-off-by: Javier Martinez Canillas >>> --- >>> >>> drivers/iio/accel/bmc150-accel-i2c.c | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/drivers/iio/accel/bmc150-accel-i2c.c b/drivers/iio/accel/bmc150-accel-i2c.c >>> index f85014fbaa12..8ffc308d5fd0 100644 >>> --- a/drivers/iio/accel/bmc150-accel-i2c.c >>> +++ b/drivers/iio/accel/bmc150-accel-i2c.c >>> @@ -81,9 +81,21 @@ static const struct i2c_device_id bmc150_accel_id[] = { >>> >>> MODULE_DEVICE_TABLE(i2c, bmc150_accel_id); >>> >>> +static const struct of_device_id bmc150_accel_of_match[] = { >>> + { .compatible = "bosch,bmc150_accel" }, >>> + { .compatible = "bosch,bmi055_accel" }, >> >> These look a bit weird, there is no reason to mirror the i2c_device_ids > > There has been a steady move for a long time to add these IDs with the plan > that we would stop automatically matching against the manufacturer free > i2c IDs. Mostly on the basis that was a hack that brought a lot Matching using OF IDs have been working for some time (since v4.10 AFAICT) after the following commit: da10c06a044b ("i2c: Make I2C ID tables non-mandatory for DT'ed devices"). The only remaining problem is with module auto-loading. > of effectively unreviewed device tree bindings. As I understand it the > eventual plan is to be able to get rid of that old path entirely... > +CC Wolfram to see what his view is on this. > I don't think we can get rid of the old path entirely since are valid use cases for it. For example when the I2C devices are registered with the i2c_new_device interface where the bus and address are declared in a struct i2c_board_info (ie: old platforms that still use board files or devices with an embedded I2C chip). What I think though is that drivers should only be required to define the device table for the firmware interface used to instantiate them. For example, a driver for a device that's DT-only should only have an OF device ID table just like a driver for an ACPI-only device only requires to have an ACPI ID table. Conversely, a driver for a device that's only instantiated using platform data should only have an I2C device ID table. If a driver supports both DT and legacy platforms, then it's OK to have both ID tables defined. What is not correct is to require OF-only drivers to have an I2C device ID table just as a workaround to have their modules auto-loading working. Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat