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* [PATCH 0/2] ARM: tegra: initial support for Colibri T30
@ 2014-05-13 17:27 stefan
  2014-05-13 17:27 ` [PATCH 1/2] ARM: tegra: enable MCP251x CAN controller and DS1307 RTC stefan
  2014-05-13 17:27 ` [PATCH 2/2] ARM: tegra: initial add of Colibri T30 stefan
  0 siblings, 2 replies; 10+ messages in thread
From: stefan @ 2014-05-13 17:27 UTC (permalink / raw)
  To: swarren, thierry.reding
  Cc: devicetree, linux, linux-kernel, stefan, marcel, linux-tegra,
	linux-arm-kernel

From: Stefan Agner <stefan@agner.ch>

This patches cooked a while in our repository and is now quite
complete. All is tested on several Colibri T30 modules and
evaluation boards by Marcel and me. The device tree is splitted
into a module part and the carrier board. The former is then
included by the latter (in this case the evaluation board). The
comments "Colibri: " represent the SO-DIMM Pin name as defined
in the Colibri standard, and should be helpful for users
adopting the device tree for other carrier boards.

Stefan Agner (2):
  ARM: tegra: enable MCP251x CAN controller and DS1307 RTC
  ARM: tegra: initial add of Colibri T30

 arch/arm/boot/dts/Makefile                    |   1 +
 arch/arm/boot/dts/tegra30-colibri-eval-v3.dts | 202 ++++++++++++++
 arch/arm/boot/dts/tegra30-colibri.dtsi        | 375 ++++++++++++++++++++++++++
 arch/arm/configs/tegra_defconfig              |   6 +
 4 files changed, 584 insertions(+)
 create mode 100644 arch/arm/boot/dts/tegra30-colibri-eval-v3.dts
 create mode 100644 arch/arm/boot/dts/tegra30-colibri.dtsi

-- 
1.9.2

^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] ARM: tegra: initial add of Colibri T30
@ 2014-05-14 16:16 Stefan Agner
       [not found] ` <107aeb48982529858267cb85c792b35e-XLVq0VzYD2Y@public.gmane.org>
  0 siblings, 1 reply; 10+ messages in thread
From: Stefan Agner @ 2014-05-14 16:16 UTC (permalink / raw)
  To: Stephen Warren
  Cc: thierry.reding, linux, devicetree, linux-arm-kernel, linux-kernel,
	linux-tegra, marcel

Am 2014-05-13 21:49, schrieb Stephen Warren:
> On 05/13/2014 11:27 AM, stefan@agner.ch wrote:
>> +	/* SPI1: Colibri SSP */
>> +	spi@7000d400 {
>> +		status = "okay";
>> +		spi-max-frequency = <25000000>;
>> +		can0: can@0 {
>> +			compatible = "microchip,mcp2515";
>> +			reg = <0>;
>> +			clocks = <&clk16m>;
>> +			interrupt-parent = <&gpio>;
>> +			interrupts = <TEGRA_GPIO(S, 0) GPIO_ACTIVE_LOW>;
>> +			spi-max-frequency = <10000000>;
> 
> So this chip doesn't get confused by a faster clock frequency when its
> chip-select line isn't asserted? I would have expected spi-max-frequency
> for the bus to be the minimum value that any device on the bus would
> tolerate.

And from the other mail:
> I'm not convinced about this. The clock signal still reaches all the
> chips, and hence still reaches some logic inside those chips. If the
> setup/hold timings aren't met (for internal parts of the chip's SPI
> state machine), then presumably all bets are off re: performance of the
> chip, irrespective of whether the CS line happens to gate how much of
> the chip actually does anything.

SPI is by default not a multi-master Bus, hence the slaves only have to
listen when the CS is asserted. I talked with our hardware expert, and
he told me that he would expect that the whole input stage (input
driver) is in reset/off logic when the CS line is not asserted. IMHO,
this makes sense, this would also save power. At least he would expect
that the communication state machine is resetted on CS assertion, so
that it doesn't matter what happend before. 

Wikipedia also states something similar. 

But, since SPI is no real standard, devices which work differently and
claim to communicate through SPI could exist :-)

I have had not seen issues with this device when using faster clocks for
other devices on the same bus.

>> +	panel: panel {
>> +		compatible = "edt,et057090dhu", "simple-panel";
> 
> The panel-simple driver doesn't seem to know about that EDT panel. How
> will it work out the display timings?

I will send a patch adding our two default panels.

Will send a second revision soon.

^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2014-05-15 18:13 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-05-13 17:27 [PATCH 0/2] ARM: tegra: initial support for Colibri T30 stefan
2014-05-13 17:27 ` [PATCH 1/2] ARM: tegra: enable MCP251x CAN controller and DS1307 RTC stefan
     [not found]   ` <77cfca0a1769d867c8d2919f0040fbd785940fef.1400001937.git.stefan-XLVq0VzYD2Y@public.gmane.org>
2014-05-13 19:57     ` Stephen Warren
2014-05-13 17:27 ` [PATCH 2/2] ARM: tegra: initial add of Colibri T30 stefan
     [not found]   ` <d45ec5351ce8ef03256061bdc4b0ba673bd40c66.1400001937.git.stefan-XLVq0VzYD2Y@public.gmane.org>
2014-05-13 19:49     ` Stephen Warren
     [not found]       ` <53727738.4080901-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2014-05-14  7:22         ` Marcel Ziswiler
2014-05-14 14:32           ` Thierry Reding
2014-05-14 15:38           ` Stephen Warren
  -- strict thread matches above, loose matches on Subject: below --
2014-05-14 16:16 Stefan Agner
     [not found] ` <107aeb48982529858267cb85c792b35e-XLVq0VzYD2Y@public.gmane.org>
2014-05-15 18:13   ` Stephen Warren

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