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[v3,1/8] tty: serial: qcom_geni_serial: Add comments for clarification

Message ID 1525378480-10296-2-git-send-email-kramasub@codeaurora.org (mailing list archive)
State Not Applicable, archived
Delegated to: Andy Gross
Headers show

Commit Message

Karthikeyan Ramasubramanian May 3, 2018, 8:14 p.m. UTC
* Document reason for newline character counting in console_write
* Document reason for disabling IRQ in the system resume operation

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
---
 drivers/tty/serial/qcom_geni_serial.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
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Patch

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index a1b3eb0..1652b1f 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -286,6 +286,10 @@  static void qcom_geni_serial_wr_char(struct uart_port *uport, int ch)
 	u32 bytes_to_send = count;
 
 	for (i = 0; i < count; i++) {
+		/*
+		 * uart_console_write() adds a carriage return for each newline.
+		 * Account for additional bytes to be written.
+		 */
 		if (s[i] == '\n')
 			bytes_to_send++;
 	}
@@ -1103,6 +1107,14 @@  static int __maybe_unused qcom_geni_serial_sys_resume_noirq(struct device *dev)
 
 	if (console_suspend_enabled && uport->suspended) {
 		uart_resume_port(uport->private_data, uport);
+		/*
+		 * uart_suspend_port() invokes port shutdown which in turn
+		 * frees the irq. uart_resume_port invokes port startup which
+		 * performs request_irq. The request_irq auto-enables the IRQ.
+		 * In addition, resume_noirq implicitly enables the IRQ and
+		 * leads to an unbalanced IRQ enable warning. Disable the IRQ
+		 * before returning so that the warning is suppressed.
+		 */
 		disable_irq(uport->irq);
 	}
 	return 0;