diff options
| author | Troy Mitchell <troy.mitchell@linux.spacemit.com> | 2025-09-25 10:02:26 +0800 |
|---|---|---|
| committer | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2025-09-25 23:15:00 +0200 |
| commit | 445522fe7aad6131b2747ae8c76f77266054cd84 (patch) | |
| tree | 8aa0b8bd176d90ad72622b61b0c856543c92a5c8 | |
| parent | 41d6f90ef5dc2841bdd09817c63a3d6188473b9b (diff) | |
i2c: spacemit: remove stop function to avoid bus error
Previously, STOP handling was split into two separate steps:
1) clear TB/STOP/START/ACK bits
2) issue STOP by calling spacemit_i2c_stop()
This left a small window where the control register was updated
twice, which can confuse the controller. While this race has not
been observed with interrupt-driven transfers, it reliably causes
bus errors in PIO mode.
Inline the STOP sequence into the IRQ handler and ensure that
control register bits are updated atomically in a single writel().
Fixes: 5ea558473fa31 ("i2c: spacemit: add support for SpacemiT K1 SoC")
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
| -rw-r--r-- | drivers/i2c/busses/i2c-k1.c | 26 |
1 files changed, 7 insertions, 19 deletions
diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c index ee08811f4087..84f132d0504d 100644 --- a/drivers/i2c/busses/i2c-k1.c +++ b/drivers/i2c/busses/i2c-k1.c @@ -267,19 +267,6 @@ static void spacemit_i2c_start(struct spacemit_i2c_dev *i2c) writel(val, i2c->base + SPACEMIT_ICR); } -static void spacemit_i2c_stop(struct spacemit_i2c_dev *i2c) -{ - u32 val; - - val = readl(i2c->base + SPACEMIT_ICR); - val |= SPACEMIT_CR_STOP | SPACEMIT_CR_ALDIE | SPACEMIT_CR_TB; - - if (i2c->read) - val |= SPACEMIT_CR_ACKNAK; - - writel(val, i2c->base + SPACEMIT_ICR); -} - static int spacemit_i2c_xfer_msg(struct spacemit_i2c_dev *i2c) { unsigned long time_left; @@ -412,7 +399,6 @@ static irqreturn_t spacemit_i2c_irq_handler(int irq, void *devid) val = readl(i2c->base + SPACEMIT_ICR); val &= ~(SPACEMIT_CR_TB | SPACEMIT_CR_ACKNAK | SPACEMIT_CR_STOP | SPACEMIT_CR_START); - writel(val, i2c->base + SPACEMIT_ICR); switch (i2c->state) { case SPACEMIT_STATE_START: @@ -429,14 +415,16 @@ static irqreturn_t spacemit_i2c_irq_handler(int irq, void *devid) } if (i2c->state != SPACEMIT_STATE_IDLE) { + val |= SPACEMIT_CR_TB | SPACEMIT_CR_ALDIE; + if (spacemit_i2c_is_last_msg(i2c)) { /* trigger next byte with stop */ - spacemit_i2c_stop(i2c); - } else { - /* trigger next byte */ - val |= SPACEMIT_CR_ALDIE | SPACEMIT_CR_TB; - writel(val, i2c->base + SPACEMIT_ICR); + val |= SPACEMIT_CR_STOP; + + if (i2c->read) + val |= SPACEMIT_CR_ACKNAK; } + writel(val, i2c->base + SPACEMIT_ICR); } err_out: |