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authorPali Rohár <pali@kernel.org>2021-02-16 11:49:11 +0100
committerPali Rohár <pali@kernel.org>2021-02-16 11:49:11 +0100
commitab1fe18841252b49e9c4b61ac499c0e7ddbee2a4 (patch)
tree69fb2a7fae6dd9f35571039e19f54cc4caf74395 /drivers
parent66306814586b1bf6bcb859aaad218ec3bb090e94 (diff)
downloadtrusted-firmware-a-ab1fe18841252b49e9c4b61ac499c0e7ddbee2a4.tar.gz
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
Diffstat (limited to 'drivers')
-rw-r--r--drivers/marvell/uart/a3700_console.S8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/marvell/uart/a3700_console.S b/drivers/marvell/uart/a3700_console.S
index 58dad7aa54..7bef7a142e 100644
--- a/drivers/marvell/uart/a3700_console.S
+++ b/drivers/marvell/uart/a3700_console.S
@@ -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