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SubjectRe: [PATCH] Make the Startech UART detection 'more correct'.
From
I was wondering what the status of this patch was for the 2.4 side?

thanks

- kumar

On Tuesday, September 9, 2003, at 06:51 PM, Tom Rini wrote:

> On Tue, Sep 09, 2003 at 05:18:59PM +0100, Russell King wrote:
>
>> On Mon, Sep 08, 2003 at 01:54:31PM -0700, Tom Rini wrote:
>>> Hello. The following patches (vs 2.4 and 2.6) make the Startech UART
>>> detection 'more correct' The problem is that on with the Motorola
>>> MPC82xx line (8245 for example) it has an internal DUART that it
>>> claims
>>> to be PC16550D compatible, and it has an additional EFR (Enhanced
>>> Feature Register) at offset 0x2, like on the Startech UARTS.
>>> However,
>>> it is not a Startech, and when it's detected as such, FIFOs don't
>>> work.
>>> The fix for this is that the Startech UARTs have a 32 byte FIFO [1]
>>> and
>>> the MPC82xx DUARTs have a 16-byte FIFO [2], to check that the FIFO
>>> size
>>> is correct for a Startech.
>>
>> size_fifo() is claimed to be unreliable at detecting the FIFO size,
>> so I don't feel safe about using it here.
>>
>> I'd suggest something like:
>>
>> serial_outp(port, UART_LCR, UART_LCR_DLAB);
>> efr = serial_in(port, UART_EFR);
>> if ((efr & 0xfc) == 0) {
>> serial_out(port, UART_EFR, 0xac | (efr & 3));
>> /* if top 6 bits return zero, its motorola */
>> if (serial_in(port, UART_EFR) == (efr & 3)) {
>> /* motorola port */
>> } else {
>> /* ST16C650V1 port */
>> }
>> /* restore old value */
>> serial_outb(port, UART_EFR, efr);
>> }
>
> Okay, from Kumar Gala (cc'ed) I've got the following patch for 2.4:
> ===== drivers/char/serial.c 1.34 vs edited =====
> --- 1.34/drivers/char/serial.c Sun Jul 6 22:33:28 2003
> +++ edited/drivers/char/serial.c Tue Sep 9 16:50:22 2003
> @@ -3741,7 +3741,10 @@
> /* Check for Startech UART's */
> serial_outp(info, UART_LCR, UART_LCR_DLAB);
> if (serial_in(info, UART_EFR) == 0) {
> - state->type = PORT_16650;
> + serial_outp(info, UART_EFR, 0xA8);
> + if (serial_in(info, UART_EFR) != 0)
> + state->type = PORT_16650;
> + serial_outp(info, UART_EFR, 0);
> } else {
> serial_outp(info, UART_LCR, 0xBF);
> if (serial_in(info, UART_EFR) == 0)
>
> And I forward ported this up to 2.6 as:
> ===== drivers/serial/8250.c 1.36 vs edited =====
> --- 1.36/drivers/serial/8250.c Tue Sep 9 07:22:12 2003
> +++ edited/drivers/serial/8250.c Tue Sep 9 16:49:07 2003
> @@ -469,8 +469,13 @@
> */
> serial_outp(up, UART_LCR, UART_LCR_DLAB);
> if (serial_in(up, UART_EFR) == 0) {
> - DEBUG_AUTOCONF("EFRv1 ");
> - up->port.type = PORT_16650;
> + serial_outp(up, UART_EFR, 0xA8);
> + if (serial_in(up, UART_EFR) != 0) {
> + DEBUG_AUTOCONF("EFRv1 ");
> + up->port.type = PORT_16650;
> + } else
> + DEBUG_AUTOCONF("Motorola 8xxx DUART ");
> + serial_outp(up, UART_EFR, 0);
> return;
> }
>
> Better?
>
> --
> Tom Rini
> http://gate.crashing.org/~trini/
> <mime-attachment>

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