linux-kernel - [PATCH V4] serial: qcom_geni_serial: To correct QUP Version detection logic

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Date:   Mon, 14 Sep 2020 12:49:17 +0530
From:   Paras Sharma <parashar@...eaurora.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jiri Slaby <jslaby@...e.com>, linux-arm-msm@...r.kernel.org,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        akashast@...eaurora.org, Paras Sharma <parashar@...eaurora.org>
Subject: [PATCH V4] serial: qcom_geni_serial: To correct QUP Version detection logic

The current implementation reduces the sampling rate by half
if qup HW version is  greater is than 2.5 by checking if the
geni SE major version is greater than 2 and geni SE minor version
is greater than 5.This implementation fails when the version is
greater than or equal to 3.

Hence, a new macro QUP_SE_VERSION_2_5 is defined having value
for major number 2 and minor number 5 as 0x20050000.Hence,if 
ver is greater than this value,sampling rate is halved. 
This logic would work for any future qup version.

Fixes: ce734600545f ("tty: serial: qcom_geni_serial: Update the oversampling rate")
Signed-off-by: Paras Sharma <parashar@...eaurora.org>
---
Changes in V4:
Created a new macro QUP_SE_VERSION_2_5 for Qup se version 2.5

 drivers/tty/serial/qcom_geni_serial.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index f0b1b47..9b74b1e 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -106,6 +106,9 @@
 /* We always configure 4 bytes per FIFO word */
 #define BYTES_PER_FIFO_WORD		4
 
+/* QUP SE VERSION value for major number 2 and minor number 5 */
+#define QUP_SE_VERSION_2_5                  0x20050000
+
 struct qcom_geni_private_data {
 	/* NOTE: earlycon port will have NULL here */
 	struct uart_driver *drv;
@@ -1000,7 +1003,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
 	sampling_rate = UART_OVERSAMPLING;
 	/* Sampling rate is halved for IP versions >= 2.5 */
 	ver = geni_se_get_qup_hw_version(&port->se);
-	if (GENI_SE_VERSION_MAJOR(ver) >= 2 && GENI_SE_VERSION_MINOR(ver) >= 5)
+	if (ver >= QUP_SE_VERSION_2_5)
 		sampling_rate /= 2;
 
 	clk_rate = get_clk_div_rate(baud, sampling_rate, &clk_div);
-- 
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