openwrt/target/linux/bcm27xx/patches-4.19/950-0610-i2c-bcm2835-Set-clock-stretch-timeout-to-35ms.patch
Adrian Schmutzler 7d7aa2fd92 brcm2708: rename target to bcm27xx
This change makes the names of Broadcom targets consistent by using
the common notation based on SoC/CPU ID (which is used internally
anyway), bcmXXXX instead of brcmXXXX.
This is even used for target TITLE in make menuconfig already,
only the short target name used brcm so far.

Despite, since subtargets range from bcm2708 to bcm2711, it seems
appropriate to use bcm27xx instead of bcm2708 (again, as already done
for BOARDNAME).

This also renames the packages brcm2708-userland and brcm2708-gpu-fw.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Acked-by: Álvaro Fernández Rojas <noltari@gmail.com>
2020-02-14 14:10:51 +01:00

48 lines
1.5 KiB
Diff

From 8d453e2193951057db696e37b9c10e7e35c18cb0 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Fri, 12 Jul 2019 15:38:35 +0100
Subject: [PATCH] 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
@@ -194,6 +194,7 @@ 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)
@@ -217,6 +218,17 @@ 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;
}