[PATCH 4.4 23/80] i2c: davinci: Avoid zero value of CLKH

From: Greg Kroah-Hartman
Date: Mon Sep 03 2018 - 13:00:48 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>

[ Upstream commit cc8de9a68599b261244ea453b38678229f06ada7 ]

If CLKH is set to 0 I2C clock is not generated at all, so avoid this value
and stretch the clock in this case.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
Acked-by: Sekhar Nori <nsekhar@xxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-davinci.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -234,12 +234,16 @@ static void i2c_davinci_calc_clk_divider
/*
* It's not always possible to have 1 to 2 ratio when d=7, so fall back
* to minimal possible clkh in this case.
+ *
+ * Note:
+ * CLKH is not allowed to be 0, in this case I2C clock is not generated
+ * at all
*/
- if (clk >= clkl + d) {
+ if (clk > clkl + d) {
clkh = clk - clkl - d;
clkl -= d;
} else {
- clkh = 0;
+ clkh = 1;
clkl = clk - (d << 1);
}