Re: [PATCH v2 1/3] dt-bindings: display: Add a property to deal with WiFi coexistence

From: Maxime Ripard <maxime@cerno.tech>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, Tim Gover <tim.gover@raspberrypi.com>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org, Rob Herring <robh+dt@kernel.org>,
	bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Frank Rowand <frowand.list@gmail.com>,
	Phil Elwell <phil@raspberrypi.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/3] dt-bindings: display: Add a property to deal with WiFi coexistence
Date: Thu, 29 Oct 2020 19:07:21 +0100	[thread overview]
Message-ID: <20201029180721.lsucxnl7kavlvibd@gilmour.lan> (raw)
In-Reply-To: <4d0028fdf797abd99f95d627e60e9322caa52596.camel@suse.de>

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Hi Nicolas,

On Thu, Oct 29, 2020 at 06:43:27PM +0100, Nicolas Saenz Julienne wrote:
> Hi maxime,
> 
> On Thu, 2020-10-29 at 14:40 +0100, Maxime Ripard wrote:
> > The RaspberryPi4 has both a WiFi chip and HDMI outputs capable of doing
> > 4k. Unfortunately, the 1440p resolution at 60Hz has a TMDS rate on the
> > HDMI cable right in the middle of the first Wifi channel.
> > 
> > Add a property to our HDMI controller, that could be reused by other
> > similar HDMI controllers, to allow the OS to take whatever measure is
> > necessary to avoid that crosstalk.
> > 
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > 
> > ---
> > 
> > Changes from v1:
> >   - Renamed the property
> >   - Split it into a separate patch
> > ---
> >  .../devicetree/bindings/display/brcm,bcm2711-hdmi.yaml      | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/display/brcm,bcm2711-hdmi.yaml b/Documentation/devicetree/bindings/display/brcm,bcm2711-hdmi.yaml
> > index 03a76729d26c..7ce06f9f9f8e 100644
> > --- a/Documentation/devicetree/bindings/display/brcm,bcm2711-hdmi.yaml
> > +++ b/Documentation/devicetree/bindings/display/brcm,bcm2711-hdmi.yaml
> > @@ -76,6 +76,12 @@ properties:
> >    resets:
> >      maxItems: 1
> >  
> > +  wifi-2.4ghz-coexistence:
> 
> I see you already renamed the property, but I can't seem to find v1 of the
> series online.

I realized I didn't put you in Cc for the first version, sorry, you'll find it here:
https://lore.kernel.org/dri-devel/20200925130744.575725-1-maxime@cerno.tech/

> Sorry if this is redundant:
> 
> I wonder if it'd make sense to prefix the property like this:
> "raspberrypi,wifi-2.4ghz-coexistence." I tend to associate the lack of prefix
> with generic properties, and also thought it was a rule. Although I may have as
> well imagined it.

Rob in the first iteration asked for the opposite :)

It used to be a vendor-specific property, and since this issue is
basically cross-platform (as long as you can support 1440p and have
WiFi), it makes sense to make this a generic property

Maxime

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