[#4943] Bfin SPORT UART driver fails to work when compiled with latest gcc, due to broken inline assembly.

Submitted By: Michael Hennerich

Open Date

2009-02-25 10:58:47 Close Date

2009-02-26 10:38:56

Priority:

Medium Assignee:

Michael Hennerich

Status:

Closed Fixed In Release:

N/A

Found In Release:

2010R1 Release:

SVN trunk

Category:

Drivers Board:

STAMP

Processor:

ALL Silicon Revision:

Is this bug repeatable?:

Yes Resolution:

Fixed

Uboot version or rev.:

Toolchain version or rev.:

gcc4.1

App binary format:

N/A

Summary: Bfin SPORT UART driver fails to work when compiled with latest gcc, due to broken inline assembly.

Details:

Bfin SPORT UART driver fails to work when compiled with latest gcc, due to broken inline assembly.

static void tx_one_byte(struct sport_uart_port *up, unsigned int value)

{

pr_debug("%s value:%x\n", __func__, value);

/* Place a Start and Stop bit */

__asm__ __volatile__ (

"R2 = b#01111111100;"

"R3 = b#10000000001;"

"%0 <<= 2;"

"%0 = %0 & R2;"

"%0 = %0 | R3;"

: "=d"(value)

: "ASTAT", "R2", "R3"

);

pr_debug("%s value:%x\n", __func__, value);

SPORT_PUT_TX(up, value);

}

tx_one_byte() assembles into this:

00000000 <_tx_one_byte>:

0: 00 00 NOP;

2: 10 32 P2 = R0;

4: 22 e1 fc 03 R2 = 0x3fc (X); /* R2=0x3fc(1020) */

8: 23 e1 01 04 R3 = 0x401 (X); /* R3=0x401(1025) */

c: 10 4f R0 <<= 0x2;

e: 10 54 R0 = R0 & R2;

10: 18 56 R0 = R0 | R3;

12: 52 ac P2 = [P2 + 0x4];

14: 82 6c P2 += 0x10; /* ( 16) */

16: 10 97 W[P2] = R0;

18: 10 00 RTS;

The second input operand (value) passed through R1 is not even used.

Instead it computes on struct sport_uart_port *up.

Inline assembly in rx_one_byte() has similar issues.

IMHO – all this assembly stuff should be converted to C.

I leave this task up to: [#3704] SPORT UART: use common infrastructure

-Michael

Follow-ups

--- Michael Hennerich 2009-02-26 10:38:56

Fixed on trunk.

The failing functions in 2008R1 branch are different from the ones on trunk.

So the issue doesn't exist there.

Closed.

-Michael

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