linux-kernel - Re: [PATCH v2 01/10] firmware: raspberrypi: Introduce rpi_firmware

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Message-ID: <160f3f542a89e0263d5d375fdae796af6017c33c.camel@suse.de>
Date:   Mon, 26 Oct 2020 17:26:17 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        linux-pwm@...r.kernel.org,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        Stefan Wahren <wahrenst@....net>,
        linux-input <linux-input@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        linux-rpi-kernel <linux-rpi-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 01/10] firmware: raspberrypi: Introduce
 rpi_firmware_put()

On Thu, 2020-10-22 at 21:46 +0300, Andy Shevchenko wrote:
> On Thu, Oct 22, 2020 at 9:06 PM Nicolas Saenz Julienne
> <nsaenzjulienne@...e.de> wrote:
> > When unbinding the firmware device we need to make sure it has no
> > consumers left. Otherwise we'd leave them with a firmware handle
> > pointing at freed memory.
> > 
> > Keep a reference count of all consumers and make sure they all finished
> > unbinding before we do.
> 
> Wait, if it's a device, why do we need all these?
> get_device() / put_device() along with module_get() / module_put()
> should be sufficient, no?

Could you expand here a little, I do see how I could use get_device()'s
reference count. But it seems to me I'd be digging way too deep into kobj in
order to get the functionality I need.

If you meant to say that it should be automatically taken care by the platform
bus, just FYI we're using 'simple-mfd' in DT. Where firmware supplier is the
parent and all consumers are children.

Regards,
Nicolas


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