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 <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
