| From stable-bounces@linux.kernel.org Tue Dec 19 23:40:57 2006 |
| Date: Wed, 20 Dec 2006 08:34:43 +0100 |
| From: Jean Delvare <khali@linux-fr.org> |
| To: stable@kernel.org |
| Message-Id: <20061220083443.45e488cb.khali@linux-fr.org> |
| Cc: Dirk Eibach <eibach@gdsys.de>, Adrian Bunk <bunk@stusta.de> |
| Subject: i2c: fix broken ds1337 initialization |
| |
| From: Dirk Eibach <eibach@gdsys.de> |
| |
| 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 <stieler@gdsys.de> |
| Signed-off-by: Dirk Eibach <eibach@gdsys.de> |
| Signed-off-by: Jean Delvare <khali@linux-fr.org> |
| Signed-off-by: Chris Wright <chrisw@sous-sol.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| --- |
| 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); |
