-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dirk Eibach On a custom board with ds1337 RTC I found that upgrade from 2.6.15 to 2.6.18 broke RTC support. The main problem are changes to ds1337_init_client(). When a ds1337 recognizes a problem (e.g. power or clock failure) bit 7 in status register is set. This has to be reset by writing 0 to status register. But since there are only 16 byte written to the chip and the first byte is interpreted as an address, the status register (which is the 16th) is never written. The other problem is, that initializing all registers to zero is not valid for day, date and month register. Funny enough this is checked by ds1337_detect(), which depends on this values not being zero. So then treated by ds1337_init_client() the ds1337 is not detected anymore, whereas the failure bit in the status register is still set. Broken by commit f9e8957937ebf60d22732a5ca9130f48a7603f60 (2.6.16-rc1, 2006-01-06). This fix is in Linus' tree since 2.6.20-rc1 (commit 763d9c046a2e511ec090a8986d3f85edf7448e7e). Signed-off-by: Dirk Stieler Signed-off-by: Dirk Eibach Signed-off-by: Jean Delvare Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/chips/ds1337.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- linux-2.6.18.7.orig/drivers/i2c/chips/ds1337.c +++ linux-2.6.18.7/drivers/i2c/chips/ds1337.c @@ -347,13 +347,19 @@ static void ds1337_init_client(struct i2 if ((status & 0x80) || (control & 0x80)) { /* RTC not running */ - u8 buf[16]; + u8 buf[1+16]; /* First byte is interpreted as address */ struct i2c_msg msg[1]; dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__); /* Initialize all, including STATUS and CONTROL to zero */ memset(buf, 0, sizeof(buf)); + + /* Write valid values in the date/time registers */ + buf[1+DS1337_REG_DAY] = 1; + buf[1+DS1337_REG_DATE] = 1; + buf[1+DS1337_REG_MONTH] = 1; + msg[0].addr = client->addr; msg[0].flags = 0; msg[0].len = sizeof(buf); -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/