diff mbox series

[4/4] media: af9035: add the formula used for the I2C speed

Message ID 01607a324c85754424b8b786ea01de0d8733702d.1570194906.git.mchehab+samsung@kernel.org (mailing list archive)
State New, archived
Headers show
Series [1/4] media: si2168: use bits instead of bool for flags | expand

Commit Message

Mauro Carvalho Chehab Oct. 4, 2019, 1:15 p.m. UTC 
A very old patch sent to the media ML used to contain the
I2C speed formula:

	https://lore.kernel.org/linux-media/1312539895.2763.33.camel@Jason-Linux/

When the ite9135 code was merged with af9035, the formula was
lost. As we might need to slow down the speed for some devices,
add the formula again.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
---
 drivers/media/usb/dvb-usb-v2/af9035.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/media/usb/dvb-usb-v2/af9035.c b/drivers/media/usb/dvb-usb-v2/af9035.c
index e555483c3077..7632b00713a0 100644
--- a/drivers/media/usb/dvb-usb-v2/af9035.c
+++ b/drivers/media/usb/dvb-usb-v2/af9035.c
@@ -1197,6 +1197,15 @@  static int af9035_frontend_attach(struct dvb_usb_adapter *adap)
 	return ret;
 }
 
+/*
+ * The I2C speed register is calculated with:
+ *	I2C speed register = (1000000000 / (24.4 * 16 * I2C_speed))
+ *
+ * The default speed register for it930x is 7, with means a
+ * speed of ~366 kbps
+ */
+#define I2C_SPEED_366K 7
+
 static int it930x_frontend_attach(struct dvb_usb_adapter *adap)
 {
 	struct state *state = adap_to_priv(adap);
@@ -1208,13 +1217,13 @@  static int it930x_frontend_attach(struct dvb_usb_adapter *adap)
 
 	dev_dbg(&intf->dev, "adap->id=%d\n", adap->id);
 
-	/* I2C master bus 2 clock speed 300k */
-	ret = af9035_wr_reg(d, 0x00f6a7, 0x07);
+	/* I2C master bus 2 clock speed 366k */
+	ret = af9035_wr_reg(d, 0x00f6a7, I2C_SPEED_366K);
 	if (ret < 0)
 		goto err;
 
-	/* I2C master bus 1,3 clock speed 300k */
-	ret = af9035_wr_reg(d, 0x00f103, 0x07);
+	/* I2C master bus 1,3 clock speed 366k */
+	ret = af9035_wr_reg(d, 0x00f103, I2C_SPEED_366K);
 	if (ret < 0)
 		goto err;