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From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Sekhar Nori <nsekhar@ti.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Ujfalusi <peter.ujfalusi@ti.com>,
	Russell King <linux@armlinux.org.uk>
Cc: linux-devicetree <devicetree@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-drm <dri-devel@lists.freedesktop.org>,
	Jyri Sarha <jsarha@ti.com>,
	arm-soc <linux-arm-kernel@lists.infradead.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH] ARM: dts: da850: specify the maximum bandwidth for tilcdc
Date: Mon, 28 Nov 2016 09:42:30 +0200	[thread overview]
Message-ID: <953743fb-54f9-fa6f-bfdd-43d92271864f@ti.com> (raw)
In-Reply-To: <8829c208-0674-43c0-8449-ef764071583f@ti.com>


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On 28/11/16 07:24, Sekhar Nori wrote:
> 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@baylibre.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).

There's a separate property for max-pixelclock. This one is maximum
pixels per second (which does sound almost the same), but the doc says
it's about the particular memory interface + LCDC combination.

But this 'max-bandwidth' does sound quite odd, as the it really should
be bytes, not pixels... Bad bindings again, which we just have to use.

 Tomi


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  reply	other threads:[~2016-11-28  7:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-25 15:37 [PATCH] ARM: dts: da850: specify the maximum bandwidth for tilcdc Bartosz Golaszewski
     [not found] ` <1480088245-8368-1-git-send-email-bgolaszewski-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
2016-11-28  5:24   ` Sekhar Nori
2016-11-28  7:42     ` Tomi Valkeinen [this message]
     [not found]       ` <953743fb-54f9-fa6f-bfdd-43d92271864f-l0cyMroinI0@public.gmane.org>
2016-11-28  7:58         ` Sekhar Nori
2016-11-28 10:43           ` Bartosz Golaszewski

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