Intel ESB2 SMBus chip seems to have an issue where it momentarily
resets the HOST_BUSY bit in the host status register. This confuses
the driver waiting for an SMBus transaction to complete. This patch
adds a workaround for the same.
Signed-off-by: Chaitanya Lala <clala@xxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-i801.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 9d2c5ad..1a04817 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -222,6 +222,7 @@ static int i801_transaction(int xact)
int status;
int result;
int timeout = 0;
+ int counter = 0;
result = i801_check_pre();
if (result < 0)
@@ -231,12 +232,34 @@ static int i801_transaction(int xact)
* INTREN, SMBSCMD are passed in xact */
outb_p(xact | I801_START, SMBHSTCNT);
+try_again:
/* We will always wait for a fraction of a second! */
do {
msleep(1);
status = inb_p(SMBHSTSTS);
} while ((status & SMBHSTSTS_HOST_BUSY) && (timeout++ < MAX_TIMEOUT));
+ /* The i801 chip resets the HOST_BUSY bit
+ * to indicate that it has completed the transaction,
+ * but a moment later sets it again. Seems like a glitch.
+ * Changed code to check the value more times if its not a timeout.
+ */
+ if (timeout < MAX_TIMEOUT) {
+ msleep(1);
+ status = inb_p(SMBHSTSTS);
+ if (status & SMBHSTSTS_HOST_BUSY) {
+ dev_warn(&I801_dev->dev, "Busy bit set again"
+ "(%02x)\n", status);
+ if (++counter < 3) {
+ dev_info(&I801_dev->dev, "Trying"
+ "again\n");
+ goto try_again;
+ }
+ dev_err(&I801_dev->dev, "No use"
+ " retrying-(%02x)\n", status);
+ }
+ }
+
result = i801_check_post(status, timeout > MAX_TIMEOUT);
if (result < 0)
return result;
--
1.6.0.4
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