[PATCH v2 01/10] i2c: i801: improve interrupt handler

Heiner Kallweit
2022-12-19T18:23:00Z

Not sure if it can happen, but better play safe: If SMBHSTSTS_BYTE_DONE
and an error flag is set, then don't trust the result and skip calling
i801_isr_byte_done(). In addition clear status bit SMBHSTSTS_BYTE_DONE
in the main interrupt handler, this allows to simplify the code a
little.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- change one expression for generating less binary code
---
drivers/i2c/busses/i2c-i801.c | 25 ++++++++-----------------
1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 1fda1eaa6..da773c563 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -558,9 +558,6 @@ static void i801_isr_byte_done(struct i801_priv *priv)
/* Write next byte, except for IRQ after last byte */
outb_p(priv->data[++priv->count], SMBBLKDAT(priv));
}
-
- /* Clear BYTE_DONE to continue with next byte */
- outb_p(SMBHSTSTS_BYTE_DONE, SMBHSTSTS(priv));
}

static irqreturn_t i801_host_notify_isr(struct i801_priv *priv)
@@ -590,7 +587,6 @@ static irqreturn_t i801_host_notify_isr(struct i801_priv *priv)
* BUS_ERR - SMI# transaction collision
* FAILED - transaction was canceled due to a KILL request
* When any of these occur, update ->status and signal completion.
- * ->status must be cleared before kicking off the next transaction.
*
* 2) For byte-by-byte (I2C read/write) transactions, one BYTE_DONE interrupt
* occurs for each byte of a byte-by-byte to prepare the next byte.
@@ -615,23 +611,18 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
}

status = inb_p(SMBHSTSTS(priv));
- if (status & SMBHSTSTS_BYTE_DONE)
+ if ((status & (SMBHSTSTS_BYTE_DONE | STATUS_ERROR_FLAGS)) == SMBHSTSTS_BYTE_DONE)
i801_isr_byte_done(priv);

/*
- * Clear remaining IRQ sources: Completion of last command, errors
- * and the SMB_ALERT signal. SMB_ALERT status is set after signal
- * assertion independently of the interrupt generation being blocked
- * or not so clear it always when the status is set.
- */
- status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS | SMBHSTSTS_SMBALERT_STS;
- if (status)
- outb_p(status, SMBHSTSTS(priv));
- status &= ~SMBHSTSTS_SMBALERT_STS; /* SMB_ALERT not reported */
- /*
- * Report transaction result.
- * ->status must be cleared before the next transaction is started.
+ * Clear IRQ sources: SMB_ALERT status is set after signal assertion
+ * independently of the interrupt generation being blocked or not
+ * so clear it always when the status is set.
*/
+ status &= STATUS_FLAGS | SMBHSTSTS_SMBALERT_STS;
+ outb_p(status, SMBHSTSTS(priv));
+
+ status &= STATUS_ERROR_FLAGS | SMBHSTSTS_INTR;
if (status) {
priv->status = status;
complete(&priv->done);
--
2.39.0