linux-kernel - Re: [PATCH] ARM: dts: da850: specify the maximum bandwidth for tilcdc

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Message-ID: <8829c208-0674-43c0-8449-ef764071583f@ti.com>
Date:   Mon, 28 Nov 2016 10:54:01 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Russell King <linux@...linux.org.uk>
CC:     LKML <linux-kernel@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        linux-drm <dri-devel@...ts.freedesktop.org>,
        linux-devicetree <devicetree@...r.kernel.org>,
        Jyri Sarha <jsarha@...com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        David Airlie <airlied@...ux.ie>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH] ARM: dts: da850: specify the maximum bandwidth for tilcdc

On Friday 25 November 2016 09:07 PM, Bartosz Golaszewski wrote:
> It has been determined that the maximum resolution supported correctly
> by tilcdc rev1 on da850 SoCs is 800x600@60. Due to memory throughput
> constraints we must filter out higher modes.
> 
> Specify the max-bandwidth property for the display node for
> da850-based boards.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> ---
>  arch/arm/boot/dts/da850.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
> index 8e30d9b..9b7c444 100644
> --- a/arch/arm/boot/dts/da850.dtsi
> +++ b/arch/arm/boot/dts/da850.dtsi
> @@ -452,6 +452,7 @@
>  			compatible = "ti,da850-tilcdc";
>  			reg = <0x213000 0x1000>;
>  			interrupts = <52>;
> +			max-bandwidth = <28800000>;

If this is effectively the max pixel clock that the device supports,
then why not use the datasheet specified value of 37.5 MHz (Tc = 26.66 ns).

Thanks,
Sekhar