Hi Stephen,
On 01/21/16 00:13, Stephen Warren wrote:
> On 01/19/2016 06:12 AM, Ralf Ramsauer wrote:
>> This patch enables the APB DMA high speed UARTs of the Jetson TK1.
>
>> diff --git a/arch/arm/boot/dts/tegra124-jetson-tk1.dts
>> b/arch/arm/boot/dts/tegra124-jetson-tk1.dts
>
>> + /* First high speed UART */
>> + serial@0,70006000 {
>> + compatible = "nvidia,tegra124-hsuart", "nvidia,tegra30-hsuart";
>> + status = "okay";
>> + };
>
> It would be nice if the comment described the HW connectivity, i.e.
> which signals the UART was connected to on the board, just like the
> comments for other IO controllers already enabled in the DT file. I'd
> suggest replacing the comment above with:
>
> /* Expansion BR_UART1_RXD/_TXD */
I'll be more verbose with commenting in the next round
>
>> + /* Second high speed UART */
>> + serial@0,70006040 {
>> + compatible = "nvidia,tegra124-hsuart", "nvidia,tegra30-hsuart";
>> + status = "okay";
>> + };
>
> ... and that commetn with:
>
> /* Expansion UART2_RXD/_TXD/_RTS/_CTS */
Ack
>
>> +
>> + /* Third high speed UART */
>> + serial@0,70006200 {
>> + compatible = "nvidia,tegra124-hsuart", "nvidia,tegra30-hsuart";
>> + status = "okay";
>> + };
>
> That UART doesn't seem to be used at all according to the schematics
> and pinmux spreadsheet. Do you have any reference to the contrary
> aside from the L4T DT file? I believe it shouldn't be enabled.
Just checked it, and yes, you're absolutely right. I used the L4T device
tree as reference. Can't tell you why, but it appears that they
activated all uarts.
This is a short excerpt of Nvidias official DT:
serial@70006000 {
compatible = "nvidia,tegra114-hsuart";
status = "okay";
};
serial@70006040 {
compatible = "nvidia,tegra114-hsuart";
status = "okay";
};
serial@70006200 {
compatible = "nvidia,tegra114-hsuart";
status = "okay";
};
serial@70006300 {
compatible = "nvidia,tegra20-uart", "nvidia,tegra114-hsuart";
console-port;
sqa-automation-port;
status = "okay";
};
This is a short excerpt of /proc/iomem of a Jetson TK1 running latest
stock L4T linux:
70006000-7000603f : /serial@70006000
70006040-7000607f : /serial@70006040
70006200-7000623f : /serial@70006200
70006300-7000631f : serial
Let me doublecheck that again - in fact only two of three high speed
UARTs are actually exposed to the expansion header. (besides the strange
fact, that nvidia seems to have all uarts enabled...)
According to [1]:
uart1 - expansion connector
uart2 - expansion connector
uart3 - ???
uart4 - DB9 RS232 connector
I'll check this in a few days again. Thanks for review, Stephen!
Ralf
[1]
http://developer.download.nvidia.com/embedded/jetson/TK1/2014-03-24/JetsonTK1_ModuleSpecification_PM375_V1.0.pdf
--
Ralf Ramsauer
GPG: 0x8F10049B
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