From 3c632fc090dab1838cedb525e09d049a903c37a6 Mon Sep 17 00:00:00 2001 From: Stanley Chu Date: Thu, 7 Aug 2025 13:32:20 +0800 Subject: [PATCH] i2c: npcm: fix consecutive dm_i2c_read/write error When doing a dm_i2c_read followed by a dm_i2c_write, the subsequent transaction may get npcm_i2c_check_sda error because the module is still busy in STOP condition in previous dm_i2c_read. Always check and wait for module to be out of busy before starting an i2c transaction. Signed-off-by: Stanley Chu Signed-off-by: Jim Liu --- drivers/i2c/npcm_i2c.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/i2c/npcm_i2c.c b/drivers/i2c/npcm_i2c.c index c64752e1467..bff0d04f1a5 100644 --- a/drivers/i2c/npcm_i2c.c +++ b/drivers/i2c/npcm_i2c.c @@ -34,6 +34,7 @@ #define SMBCTL3_SDA_LVL BIT(6) /* SMBCST */ +#define SMBCST_BUSY BIT(0) #define SMBCST_BB BIT(1) #define SMBCST_TGSCL BIT(5) @@ -479,11 +480,17 @@ static int npcm_i2c_xfer(struct udevice *dev, struct npcm_i2c_bus *bus = dev_get_priv(dev); struct npcm_i2c_regs *reg = bus->reg; int ret = 0, err = 0; + u8 val; if (nmsgs < 1 || nmsgs > 2) { printf("%s: commands not support\n", __func__); return -EREMOTEIO; } + + /* Wait for module out of busy */ + if (readb_poll_timeout(®->cst, val, !(val & SMBCST_BUSY), 1000)) + return -EBUSY; + /* clear ST register */ writeb(0xFF, ®->st); -- 2.47.3