UCC UART

[Tabi Timur-B04825]

Gary Thomas wrote:
> I'm still trying to get UCC UART to work on my MPC8358 with
> the 2.6.33.3 kernel.
>
> When I try to send data to the port, there is no output, not
> even any interrupts on the device. What I see is that the UART
> driver seems to initialize fine and pushes characters into
> the output buffers & descriptors. However, there are no
> interrupts hence it just sits there...
>
> My device tree entry for this device now looks like this:
> /* ttyQE0 (UCC3) */
> serial_qe0: serial at 4000 {
> device_type = "serial";
> compatible = "ucc_uart";
> cell-index = <3>;
> reg = <0x2200 0x200>;
> interrupts = <34>;
> interrupt-parent = <&qeic>;
> port-number = <0>;
> rx-clock-name = "brg1";
> tx-clock-name = "brg1";
> };

You might try assigning different BRGs to TX and RX.

>
> * Are there any known issues with this driver?

Heh. :-)

I'd say that there are plenty of unknown issues with this driver/hardware. 
For some reason, QE UART is just unreliable.  I've had several people try to 
use the QE for UART, and almost everyone has problems with it.

> * Is there any way to get a handle on why no data is moving?

The QE is a black box.  If you're programming it correctly but it doesn't do 
what it's supposed to, there's almost no way to debug it.

> * Is there some way to tell if the QE even sees the descriptors?

Not to my knowledge.

> * The driver and documentation mention a "soft UART" mode for
> chips with broken UART hardware. How do I know if my board
> has functioning UART hardware?

I believe only the 8323 and the 8360 have broken UARTs.  Those are the only 
ones that have the microcode update that enable soft-UART, anyway.

>
> Note: I have UCC1+UCC2 working great with ethernet.
>
> Thanks for any pointers or ideas

You should contact Freescale support and ask them for help.  Even though I 
wrote the Linux driver, I have no "inside" connection to the QE team here at 
Freescale.
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