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i2c: s3c24xx: fix transferring more than one message in polling mode
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To properly handle ACK on the bus when transferring more than one
message in polling mode, move the polling handling loop from
s3c24xx_i2c_message_start() to s3c24xx_i2c_doxfer(). This way
i2c_s3c_irq_nextbyte() is always executed till the end, properly
acknowledging the IRQ bits and no recursive calls to
i2c_s3c_irq_nextbyte() are made.

While touching this, also fix finishing transfers in polling mode by
using common code path and always waiting for the bus to become idle
and disabled.

Fixes: 117053f ("i2c: s3c2410: Add polling mode support")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Marek Szyprowski authored and Wolfram Sang committed Jan 18, 2024
1 parent 0d9cf23 commit 990489e
Showing 1 changed file with 10 additions and 17 deletions.
27 changes: 10 additions & 17 deletions drivers/i2c/busses/i2c-s3c2410.c
Original file line number Diff line number Diff line change
Expand Up @@ -279,16 +279,6 @@ static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,

stat |= S3C2410_IICSTAT_START;
writel(stat, i2c->regs + S3C2410_IICSTAT);

if (i2c->quirks & QUIRK_POLL) {
while ((i2c->msg_num != 0) && is_ack(i2c)) {
i2c_s3c_irq_nextbyte(i2c, stat);
stat = readl(i2c->regs + S3C2410_IICSTAT);

if (stat & S3C2410_IICSTAT_ARBITR)
dev_err(i2c->dev, "deal with arbitration loss\n");
}
}
}

static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
Expand Down Expand Up @@ -694,7 +684,7 @@ static void s3c24xx_i2c_wait_idle(struct s3c24xx_i2c *i2c)
static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
struct i2c_msg *msgs, int num)
{
unsigned long timeout;
unsigned long timeout = 0;
int ret;

ret = s3c24xx_i2c_set_master(i2c);
Expand All @@ -714,16 +704,19 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
s3c24xx_i2c_message_start(i2c, msgs);

if (i2c->quirks & QUIRK_POLL) {
ret = i2c->msg_idx;
while ((i2c->msg_num != 0) && is_ack(i2c)) {
unsigned long stat = readl(i2c->regs + S3C2410_IICSTAT);

if (ret != num)
dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
i2c_s3c_irq_nextbyte(i2c, stat);

goto out;
stat = readl(i2c->regs + S3C2410_IICSTAT);
if (stat & S3C2410_IICSTAT_ARBITR)
dev_err(i2c->dev, "deal with arbitration loss\n");
}
} else {
timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
}

timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);

ret = i2c->msg_idx;

/*
Expand Down

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