linux-kernel - Re: [PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox into separate modules

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Date:   Mon, 25 Mar 2019 12:22:20 -0600
From:   Nick Crews <ncrews@...omium.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Benson Leung <bleung@...omium.org>, linux-leds@...r.kernel.org,
        jacek.anaszewski@...il.com, Pavel Machek <pavel@....cz>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Duncan Laurie <dlaurie@...omium.org>,
        Simon Glass <sjg@...gle.com>,
        Guenter Roeck <groeck@...gle.com>,
        Dmitry Torokhov <dtor@...gle.com>
Subject: Re: [PATCH 1/3] platform/chrome: wilco_ec: Split core and mailbox
 into separate modules

On Mon, Mar 25, 2019 at 11:18 AM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> Hi Nick,
>
> Thanks for the patch, some comments below.
>
> On 21/3/19 23:13, Nick Crews wrote:
> > It was bad design to lump the mailbox interface to the Wilco EC into the
> > same module as the code module, which loads all the subdrivers:
>
> Typo: s/code/core/?
>
> > - This required the sub-drivers to depend on the core, which doesn't
> > really make sense, they should just depend on the mailbox interface.
> > - It caused problems with circular dependencies: An upcoming keyboard
> > backlight driver depends on the mailbox interface, which in the old
> > architecture makes it also depend on the core driver. However, the core
> > driver should be able to detect whether or not the keyboard
> > backlight is available, so the core module depends on the backlight
> > driver. This created a circular dependency.
> >
> > By splitting up the mailbox interface and core driver into separate
> > modules, it fixes both of these problems.
> >
> > Signed-off-by: Nick Crews <ncrews@...omium.org>
> > ---
> >  drivers/platform/chrome/wilco_ec/Makefile  | 6 ++++--
> >  drivers/platform/chrome/wilco_ec/core.c    | 2 +-
> >  drivers/platform/chrome/wilco_ec/mailbox.c | 6 ++++++
> >  3 files changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
> > index 063e7fb4ea17..9706aeb20ccb 100644
> > --- a/drivers/platform/chrome/wilco_ec/Makefile
> > +++ b/drivers/platform/chrome/wilco_ec/Makefile
> > @@ -1,6 +1,8 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >
> > -wilco_ec-objs                                := core.o mailbox.o
> > -obj-$(CONFIG_WILCO_EC)                       += wilco_ec.o
> > +wilco_ec_mailbox-objs                        := mailbox.o
> > +obj-$(CONFIG_WILCO_EC)                       += wilco_ec_mailbox.o
> > +wilco_ec_core-objs                   := core.o
> > +obj-$(CONFIG_WILCO_EC)                       += wilco_ec_core.o
>
> Odd, same config definition (CONFIG_WILCO_EC) for two different kernel modules?

The mailbox and core modules will always be wanted together, so I
figured just keep it
as one config option. I think it would be confusing to add unnecessary
config options.
Is there a good alternative?

>
> >  wilco_ec_debugfs-objs                        := debugfs.o
> >  obj-$(CONFIG_WILCO_EC_DEBUGFS)               += wilco_ec_debugfs.o
> > diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
> > index 05e1e2be1c91..ece30874f35f 100644
> > --- a/drivers/platform/chrome/wilco_ec/core.c
> > +++ b/drivers/platform/chrome/wilco_ec/core.c
> > @@ -20,7 +20,7 @@
> >
> >  #include "../cros_ec_lpc_mec.h"
> >
> > -#define DRV_NAME "wilco-ec"
> > +#define DRV_NAME "wilco-ec-core"
> >
> >  static struct resource *wilco_get_resource(struct platform_device *pdev,
> >                                          int index)
> > diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
> > index 14355668ddfa..ca6b92ce7e6d 100644
> > --- a/drivers/platform/chrome/wilco_ec/mailbox.c
> > +++ b/drivers/platform/chrome/wilco_ec/mailbox.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/delay.h>
> >  #include <linux/device.h>
> >  #include <linux/io.h>
> > +#include <linux/module.h>
> >  #include <linux/platform_data/wilco-ec.h>
> >  #include <linux/platform_device.h>
> >
> > @@ -235,3 +236,8 @@ int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg)
> >
> >  }
> >  EXPORT_SYMBOL_GPL(wilco_ec_mailbox);
> > +
> > +MODULE_AUTHOR("Nick Crews <ncrews@...omium.org>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("ChromeOS Wilco Embedded Controller mailbox interface");
> > +MODULE_ALIAS("platform:wilco-ec-mailbox");
> >
>
> Thanks,
> - Enric