linux-kernel - Re: [PATCH v3 1/8] mfd / platform: cros_ec: use devm_mfd_add

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Date:   Tue, 4 Dec 2018 09:22:54 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     gwendal@...omium.org, drinkcat@...omium.org,
        linux-kernel@...r.kernel.org, groeck@...omium.org,
        kernel@...labora.com, bleung@...omium.org,
        Olof Johansson <olof@...om.net>
Subject: Re: [PATCH v3 1/8] mfd / platform: cros_ec: use devm_mfd_add_devices.

On Mon, 03 Dec 2018, Enric Balletbo i Serra wrote:

> Hi Lee,
> 
> On 3/12/18 11:32, Lee Jones wrote:
> > On Tue, 27 Nov 2018, Enric Balletbo i Serra wrote:
> > 
> >> Use devm_mfd_add_devices() for adding cros-ec core MFD child devices. This
> >> reduces the need of remove callback from platform/chrome for removing the
> >> MFD child devices.
> >>
> >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> >> ---
> >>
> >> Changes in v3:
> >> - Removed cros_ec_remove from include file.
> >>
> >> Changes in v2:
> >> - Use devm only for the cros-ec core.
> >>
> >>  drivers/mfd/cros_ec.c                 | 14 +++-----------
> >>  drivers/mfd/cros_ec_dev.c             |  1 +
> >>  drivers/platform/chrome/cros_ec_i2c.c | 10 ----------
> >>  drivers/platform/chrome/cros_ec_lpc.c |  4 ----
> >>  drivers/platform/chrome/cros_ec_spi.c | 11 -----------
> >>  include/linux/mfd/cros_ec.h           | 10 ----------
> >>  6 files changed, 4 insertions(+), 46 deletions(-)
> > 
> > Nice patch.
> > 
> > Just one question:
> > 
> > [...]
> > 
> >> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> >> index 8f9d6964173e..ff788d3e6d5f 100644
> >> --- a/drivers/mfd/cros_ec_dev.c
> >> +++ b/drivers/mfd/cros_ec_dev.c
> >> @@ -493,6 +493,7 @@ static int ec_device_remove(struct platform_device *pdev)
> >>  
> >>  	cros_ec_debugfs_remove(ec);
> >>  
> >> +	mfd_remove_devices(ec->dev);
> > 
> > Why is this still required?
> > 
> 
> Hmm, maybe that line shouldn't be here as is not really related to this patch,
> it's more a fix for the cros_ec_dev to remove those cells that are registered
> with mfd_add_devices.
> 
> Actually what we have is cros_ec that instantiates one or two cros_ec_dev
> (depends on the platform) and cros_ec_dev instantiating different subdrivers.
> The purpose of the patch was use the device managed resource for the cros_ec
> driver, I did not touch the cros_ec_dev driver

Also, if you are using managed devices, you shouldn't need to call
mfd_remove_devices() at all, since it will be called for you when the
device is torn down, right?

> >>  	cdev_del(&ec->cdev);
> >>  	device_unregister(&ec->class_dev);
> >>  	return 0;
> > 
> > [...]
> > 

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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