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i2c: npcm: fix consecutive dm_i2c_read/write error

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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 <yschu@nuvoton.com>
Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
This commit is contained in:
Stanley Chu
2025-08-07 13:32:20 +08:00
committed by Tom Rini
parent ad3a33e577
commit 3c632fc090
1 changed files with 7 additions and 0 deletions
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7
drivers/i2c/npcm_i2c.c
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@@ -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(&reg->cst, val, !(val & SMBCST_BUSY), 1000))
return -EBUSY;
/* clear ST register */
writeb(0xFF, &reg->st);