linux-kernel - Re: [PATCH V3 2/5] dts/imx6q-b850v3: Configure IPU assignment order

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Message-ID: <1470041647.6640.3.camel@pengutronix.de>
Date:	Mon, 01 Aug 2016 10:54:07 +0200
From:	Lucas Stach <l.stach@...gutronix.de>
To:	Peter Senna Tschudin <peter.senna@...labora.com>
Cc:	robh+dt@...nel.org, mark.rutland@....com, shawnguo@...nel.org,
	kernel@...gutronix.de, fabio.estevam@....com,
	linux@...linux.org.uk, airlied@...ux.ie, p.zabel@...gutronix.de,
	davem@...emloft.net, geert@...ux-m68k.org,
	gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
	mchehab@...nel.org, linux@...ck-us.net, treding@...dia.com,
	architt@...eaurora.org, ykk@...k-chips.com,
	andrey.gusakov@...entembedded.com,
	boris.brezillon@...e-electrons.com, enric.balletbo@...labora.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	dri-devel@...ts.freedesktop.org, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH V3 2/5] dts/imx6q-b850v3: Configure IPU assignment order

Am Sonntag, den 31.07.2016, 21:55 +0200 schrieb Peter Senna Tschudin:
> As the IPU has combined limitations across multiple crtcs, and as that
> can't be communicated to userspace at the moment, reorder the crtcs to
> allow support to two Full-HD monitors by avoiding assigning two
> monitors to a single IPU.
> 
> Cc: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> Cc: Philipp Zabel <p.zabel@...gutronix.de>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Fabio Estevam <fabio.estevam@....com>
> Signed-off-by: Peter Senna Tschudin <peter.senna@...labora.com>

NACK. This is a userspace issue. Changing the assignment order of the
CRTCs just shifts the failure to a userspace that want to use CRTC 0 and
2 now.

imx-drm just got atomic support and with the atomic check it should be
possible to inform userspace in a reasonable way about such issues.

Regards,
Lucas

> ---
> Unchanged from V2.
> 
> Changes from V1:
>  - New commit message
> 
>  arch/arm/boot/dts/imx6q-b850v3.dts | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/imx6q-b850v3.dts b/arch/arm/boot/dts/imx6q-b850v3.dts
> index 167f744..88a70de 100644
> --- a/arch/arm/boot/dts/imx6q-b850v3.dts
> +++ b/arch/arm/boot/dts/imx6q-b850v3.dts
> @@ -51,6 +51,11 @@
>  	chosen {
>  		stdout-path = &uart3;
>  	};
> +
> +	display-subsystem {
> +		compatible = "fsl,imx-display-subsystem";
> +		ports = <&ipu1_di0>, <&ipu2_di0>, <&ipu1_di1>, <&ipu2_di1>;
> +	};
>  };
>  
>  &clks {