On 08.10.21 02:33, Guenter Roeck wrote:
> This reverts commit cb011044e34c ("watchdog: iTCO_wdt: Account for
> rebooting on second timeout") and commit aec42642d91f ("watchdog: iTCO_wdt:
> Fix detection of SMI-off case") since those patches cause a regression
> on certain boards (https://bugzilla.kernel.org/show_bug.cgi?id=213809).
>
> While this revert may result in some boards to only reset after twice
> the configured timeout value, that is still better than a watchdog reset
> after half the configured value.
>
> Fixes: cb011044e34c ("watchdog: iTCO_wdt: Account for rebooting on second timeout")
> Fixes: aec42642d91f ("watchdog: iTCO_wdt: Fix detection of SMI-off case")
> Cc: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> Cc: Mantas Mikulėnas <grawity@xxxxxxxxx>
> Reported-by: Javier S. Pedro <debbugs@xxxxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/watchdog/iTCO_wdt.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index 643c6c2d0b72..ced2fc0deb8c 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -71,8 +71,6 @@
> #define TCOBASE(p) ((p)->tco_res->start)
> /* SMI Control and Enable Register */
> #define SMI_EN(p) ((p)->smi_res->start)
> -#define TCO_EN (1 << 13)
> -#define GBL_SMI_EN (1 << 0)
>
> #define TCO_RLD(p) (TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
> #define TCOv1_TMR(p) (TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
> @@ -357,12 +355,8 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
>
> tmrval = seconds_to_ticks(p, t);
>
> - /*
> - * If TCO SMIs are off, the timer counts down twice before rebooting.
> - * Otherwise, the BIOS generally reboots when the SMI triggers.
> - */
> - if (p->smi_res &&
> - (inl(SMI_EN(p)) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
> + /* For TCO v1 the timer counts down twice before rebooting */
> + if (p->iTCO_version == 1)
> tmrval /= 2;
>
> /* from the specs: */
> @@ -527,7 +521,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
> * Disables TCO logic generating an SMI#
> */
> val32 = inl(SMI_EN(p));
> - val32 &= ~TCO_EN; /* Turn off SMI clearing watchdog */
> + val32 &= 0xffffdfff; /* Turn off SMI clearing watchdog */
> outl(val32, SMI_EN(p));
> }
>
>
Sigh, how broken is this architecture of the iTCO? Agreed, this leaves
no option then.
BTW, the fact that we saw an inconsistency in read-back timeout
indicates that there is still an issue for the remaining /= 2 case
(means v1), but I'm loosing interest in fixing those issues, given how
hard it is to test broadly without breaking users first.
Jan
--
Siemens AG, T RDA IOT
Corporate Competence Center Embedded Linux
