linux-kernel - Re: [PATCH v2 6/7] platform: x86: Add intel_skl

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Message-ID: <YAgXlgLauIGEe05w@smile.fi.intel.com>
Date:   Wed, 20 Jan 2021 13:44:22 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Daniel Scally <djrscally@...il.com>, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-i2c@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        devel@...ica.org, rjw@...ysocki.net, lenb@...nel.org,
        andy@...nel.org, mika.westerberg@...ux.intel.com,
        linus.walleij@...aro.org, bgolaszewski@...libre.com,
        wsa@...nel.org, lee.jones@...aro.org, hdegoede@...hat.com,
        mgross@...ux.intel.com, robert.moore@...el.com,
        erik.kaneda@...el.com, sakari.ailus@...ux.intel.com,
        kieran.bingham@...asonboard.com
Subject: Re: [PATCH v2 6/7] platform: x86: Add intel_skl_int3472 driver

On Wed, Jan 20, 2021 at 06:18:53AM +0200, Laurent Pinchart wrote:
> On Tue, Jan 19, 2021 at 07:43:15PM +0200, Andy Shevchenko wrote:
> > On Tue, Jan 19, 2021 at 06:36:31PM +0200, Laurent Pinchart wrote:
> > > On Tue, Jan 19, 2021 at 11:33:58AM +0200, Andy Shevchenko wrote:
> > > > On Tue, Jan 19, 2021 at 12:11:40AM +0000, Daniel Scally wrote:
> > > > > On 18/01/2021 21:19, Daniel Scally wrote:

...

> > > > See my previous reply. TL;DR: you have to modify clk-gpio.c to export couple of
> > > > methods to be able to use it as a library.
> > > 
> > > That seems really overkill given the very simple implementation of the
> > > clock provided here.
> > 
> > Less code in the end is called an overkill? Hmm...
> > I think since we in Linux it's better to utilize what it provides. Do you want
> > me to prepare a patch to show that there is no overkill at all?
> 
> The amount of code we would save it very small. It's not necessarily a
> bad idea, but I think such an improvement could be made on top, it
> shouldn't block this series.

Okay, let's wait what Dan will say on this.
I can probably help to achieve this improvement sooner than later.

...

> > > > > (also, Laurent, if we did it this way we wouldn't be able to also handle
> > > > > the led-indicator GPIO here without some fairly major rework)
> > > > 
> > > > LED indicators are done as LED class devices (see plenty of examples in PDx86
> > > > drivers: drivers/platform/x86/)
> > > 
> > > How do you expose the link between the sensor and its indicator LED to
> > > userspace ? Isn't it better to handle it in the kernel to avoid rogue
> > > userspace turning the camera on without notifying the user ?
> > 
> > I didn't get this. It's completely a LED handling driver business. We may
> > expose it to user space or not, but it's orthogonal to the usage of LED class
> > IIUC. Am I mistaken here?
> 
> If it stays internal to the kernel and is solely controlled from the
> int3472 driver, there's no need to involve the LED class. If we want to
> expose the privacy LED to userspace then the LED framework is the way to
> go, but we will also need to find a way to expose the link between the
> camera sensor and the LED to userspace. If there are two privacy LEDs,
> one for the front sensor and one for the back sensor, userspace will
> need to know which is which.

I see. For now we probably can keep GPIO LED implementation internally.

-- 
With Best Regards,
Andy Shevchenko