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marvell: uart: a3720: Fix comments in console_a3700_core_init() function 

The delay loop executes 3 instructions. These 3 instructions are executed
in 2 processor ticks and 30000 iterations on a 600 MHz CPU should yield
approximately 100 us. This means we are waiting 2 ms, not 20 ms, for TX
FIFO to be empty.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: I2cccad405bcc73cd6d1062adc0205c405c16c15f
This commit is contained in:
Pali Rohár 2021-02-16 11:49:11 +01:00
parent 6630681458
commit ab1fe18841
1 changed files with 4 additions and 4 deletions
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8
drivers/marvell/uart/a3700_console.S
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@ -60,10 +60,10 @@ func console_a3700_core_init
str w3, [x0, #UART_POSSR_REG]
/*
* Wait for the TX (THR and TSR) to be empty. If wait for 20ms, the TX FIFO is
* Wait for the TX (THR and TSR) to be empty. If wait for 2ms, the TX FIFO is
* still not empty, TX FIFO will reset by all means.
*/
mov w1, #20 /* max time out 20ms */
mov w1, #20 /* max time out 20 * 100 us */
2:
/* Check whether TX (THR and TSR) is empty */
ldr w3, [x0, #UART_STATUS_REG]
@ -72,13 +72,13 @@ func console_a3700_core_init
b.ne 4f
/* Delay */
mov w2, #30000
mov w2, #30000 /* 30000 cycles of below 3 instructions on 600 MHz CPU ~~ 100 us */
3:
sub w2, w2, #1
cmp w2, #0
b.ne 3b
/* Check whether 10ms is waited */
/* Check whether wait timeout expired */
sub w1, w1, #1
cmp w1, #0
b.ne 2b