Re: [PATCH 4/4] watchdog: it87_wdt: Keep WDTCTRL bit 3 unmodified for IT8784/IT8786

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 7/6/24 12:06, James Hilliard wrote:
On Wed, Dec 13, 2023 at 1:45 AM Werner Fischer <devlists@xxxxxxxx> wrote:

WDTCTRL bit 3 sets the mode choice for the clock input of IT8784/IT8786.
Some motherboards require this bit to be set to 1 (= PCICLK mode),
otherwise the watchdog functionality gets broken. The BIOS of those
motherboards sets WDTCTRL bit 3 already to 1.

Instead of setting all bits of WDTCTRL to 0 by writing 0x00 to it, keep
bit 3 of it unchanged for IT8784/IT8786 chips. In this way, bit 3 keeps
the status as set by the BIOS of the motherboard.

I have a board(https://qotom.net/product/94.html) with an IT8786
revision 4 which is recognized but doesn't seem to ever trigger. Did
your IT8786 based boards show revision 4 like mine do?

[    1.607590] it87_wdt: Chip IT8786 revision 4 initialized.
timeout=60 sec (nowayout=0 testmode=0)
[    2.367608] systemd[1]: Using hardware watchdog 'IT87 WDT', version
1, device /dev/watchdog0

Docs I have from the vendor just show bit 3 as reserved:

https://qotom.us/download/SuperIO/IT8786_B_V0.2_industrial_111412.pdf

8.10.8 Watch Dog Timer Control Register (Index=71h, Default=00h)

Bit      Description
7        WDT is reset upon a CIR interrupt.
6        WDT is reset upon a KBC(Mouse) interrupt.
5        WDT is reset upon a KBC(Keyboard) interrupt.
4        WDT Status will not be cleared by VCCOK or LRESET#, and only
be cleared while write one to WDT Status
          1: Enable
          0: Disable
3-2      Reserved
1        Force Time-out
          This bit is self-cleared.
0        WDT Status
          1: WDT value is equal to 0.
          0: WDT value is not is equal to 0.

Any idea why the docs I have would just show bit 3 as reserved?

Did you have any information from your vendor under what conditions
bit 3 should be set?


On ITE8784E bit 3 is "External CLK_IN Select".


Watchdog tests have been successful with this patch with the following
systems:
   IT8784: Thomas-Krenn LES plus v2 (YANLING YL-KBRL2 V2)
   IT8786: Thomas-Krenn LES plus v3 (YANLING YL-CLU L2)
   IT8786: Thomas-Krenn LES network 6L v2 (YANLING YL-CLU6L)

Link: https://lore.kernel.org/all/140b264d-341f-465b-8715-dacfe84b3f71@xxxxxxxxxxxx/

Signed-off-by: Werner Fischer <devlists@xxxxxxxx>
---
  drivers/watchdog/it87_wdt.c | 14 +++++++++++++-
  1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index f6a344c002af..9297a5891912 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -258,6 +258,7 @@ static struct watchdog_device wdt_dev = {
  static int __init it87_wdt_init(void)
  {
         u8  chip_rev;
+       u8 ctrl;
         int rc;

         rc = superio_enter();
@@ -316,7 +317,18 @@ static int __init it87_wdt_init(void)

         superio_select(GPIO);
         superio_outb(WDT_TOV1, WDTCFG);
-       superio_outb(0x00, WDTCTRL);
+
+       switch (chip_type) {
+       case IT8784_ID:
+       case IT8786_ID:
+               ctrl = superio_inb(WDTCTRL);

If I print this value out like this:
pr_warn("WDTCTRL initial: %02x\n", ctrl);

I get 0x00:
[    1.607480] it87_wdt: WDTCTRL initial: 00

Do you think it's required that the kernel set bit 3 for some boards for
the watchdog to work correctly if not set by the BIOS?

That is done for none of the boards. The code in question does not _clear_ the bit,
but it is never set.

Or maybe it's required to configure additional registers?

I would suspect that to be the case. You might want to check register 0x72.

Guenter





[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux