git.openwrt.org Git - openwrt/openwrt.git/blob

   1 From ceee7776c010c5f09d30985c9e5223b363a6172a Mon Sep 17 00:00:00 2001
   2 From: Sven Eckelmann <sven@narfation.org>
   3 Date: Sun, 10 Aug 2025 20:05:15 +0200
   4 Subject: [PATCH] i2c: rtl9300: Increase timeout for transfer polling
   5
   6 The timeout for transfers was only set to 2ms. Because of this relatively
   7 low limit, 12-byte read operations to the frontend MCU of a RTL8239 POE PSE
   8 chip cluster was consistently resulting in a timeout.
   9
  10 The original OpenWrt downstream driver [1] was not using any timeout limit
  11 at all. This is also possible by setting the timeout_us parameter of
  12 regmap_read_poll_timeout() to 0. But since the driver currently implements
  13 the ETIMEDOUT error, it is more sensible to increase the timeout in such a
  14 way that communication with the (quite common) Realtek I2C-connected POE
  15 management solution is possible.
  16
  17 [1] https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/realtek/files-6.12/drivers/i2c/busses/i2c-rtl9300.c;h=c4d973195ef39dc56d6207e665d279745525fcac#l202
  18
  19 Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller")
  20 Signed-off-by: Sven Eckelmann <sven@narfation.org>
  21 Cc: <stable@vger.kernel.org> # v6.13+
  22 Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
  23 Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
  24 Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
  25 Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-3-cd9dca0db722@narfation.org
  26
  27 diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
  28 index 4a538b266080..4a282d57e2c1 100644
  29 --- a/drivers/i2c/busses/i2c-rtl9300.c
  30 +++ b/drivers/i2c/busses/i2c-rtl9300.c
  31 @@ -175,7 +175,7 @@ static int rtl9300_i2c_execute_xfer(struct rtl9300_i2c *i2c, char read_write,
  32                 return ret;
  33
  34         ret = regmap_read_poll_timeout(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1,
  35 -                                      val, !(val & RTL9300_I2C_MST_CTRL1_I2C_TRIG), 100, 2000);
  36 +                                      val, !(val & RTL9300_I2C_MST_CTRL1_I2C_TRIG), 100, 100000);
  37         if (ret)
  38                 return ret;
  39
  40 --
  41 2.48.1
  42