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openwrt/target/linux/bcm27xx/patches-6.6/950-0166-i2c-bcm2835-Set-clock-stretch-timeout-to-35ms.patch
Álvaro Fernández Rojas 8c405cdccc bcm27xx: add 6.6 kernel patches
The patches were generated from the RPi repo with the following command:
git format-patch v6.6.34..rpi-6.1.y

Some patches needed rebasing and, as usual, the applied and reverted, wireless
drivers, Github workflows, READMEs and defconfigs patches were removed.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2024-06-18 18:52:49 +02:00

48 lines
1.5 KiB
Diff

From 3f22ee90ee63243824307e530e3032b7d052cfa6 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Fri, 12 Jul 2019 15:38:35 +0100
Subject: [PATCH 0166/1085] 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(+)
--- 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(stru
{
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(stru
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;
}