mirror of
https://github.com/Ysurac/openmptcprouter.git
synced 2025-03-09 15:40:20 +00:00
52 lines
1.7 KiB
Diff
52 lines
1.7 KiB
Diff
From 0ac5e2a583638e8dd5d1fd523553f21744456f09 Mon Sep 17 00:00:00 2001
|
|
From: Phil Elwell <phil@raspberrypi.org>
|
|
Date: Fri, 12 Jul 2019 15:38:35 +0100
|
|
Subject: [PATCH 190/726] i2c: bcm2835: Set clock-stretch timeout to 35ms
|
|
|
|
The BCM2835 I2C blocks have a register to set the clock-stretch
|
|
timeout - how long the device is allowed to hold SCL low - in bus
|
|
cycles. The current driver doesn't write to the register, therefore
|
|
the default value of 64 cycles is being used for all devices.
|
|
|
|
Set the timeout to the value recommended for SMBus - 35ms.
|
|
|
|
See: https://github.com/raspberrypi/linux/issues/3064
|
|
|
|
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
|
|
---
|
|
drivers/i2c/busses/i2c-bcm2835.c | 12 ++++++++++++
|
|
1 file changed, 12 insertions(+)
|
|
|
|
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
|
|
index 394282a37f67..d768247c7e50 100644
|
|
--- a/drivers/i2c/busses/i2c-bcm2835.c
|
|
+++ b/drivers/i2c/busses/i2c-bcm2835.c
|
|
@@ -193,6 +193,7 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
|
|
{
|
|
struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
|
|
u32 redl, fedl;
|
|
+ u32 clk_tout;
|
|
u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate);
|
|
|
|
if (divider == -EINVAL)
|
|
@@ -216,6 +217,17 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
|
|
bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL,
|
|
(fedl << BCM2835_I2C_FEDL_SHIFT) |
|
|
(redl << BCM2835_I2C_REDL_SHIFT));
|
|
+
|
|
+ /*
|
|
+ * Set the clock stretch timeout to the SMBUs-recommended 35ms.
|
|
+ */
|
|
+ if (rate > 0xffff*1000/35)
|
|
+ clk_tout = 0xffff;
|
|
+ else
|
|
+ clk_tout = 35*rate/1000;
|
|
+
|
|
+ bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout);
|
|
+
|
|
return 0;
|
|
}
|
|
|
|
--
|
|
2.33.1
|
|
|