linux-kernel - Re: [PATCH] EDAC/altera: Warm Reset option for Stratix10 peripheral DBE

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Date:   Tue, 4 Jun 2019 18:38:48 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     James Morse <james.morse@....com>
Cc:     thor.thayer@...ux.intel.com, bp@...en8.de, mchehab@...nel.org,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        Mark Rutland <Mark.Rutland@....com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] EDAC/altera: Warm Reset option for Stratix10 peripheral
 DBE

On Tue, Jun 04, 2019 at 06:23:15PM +0100, James Morse wrote:
> Hi Thor,
>
> (CC: +Mark, Lorenzo and Sudeep for PSCI.
> How should SYSTEM_RESET2 be used for a vendor-specific reset?
>

Initially it was indented to be used by passing command line argument
"reboot=w" or "reboot=warm" as specified in kernel document[1]

However it was enhanced and enabled specifically for panic by
Commit b287a25a7148 ("panic/reboot: allow specifying reboot_mode for panic only")

IIUC you can now pass "reboot=panic_warm" to just set reboot_mode to
WARM when there's a panic. SYSTEM_RESET2 gets called whenever reboot_mode
is set to WARM/SOFT

> The original patch is:
> lore.kernel.org/r/1559594269-10077-1-git-send-email-thor.thayer@...ux.intel.com
> )
>
> On 03/06/2019 21:37, thor.thayer@...ux.intel.com wrote:
> > From: Thor Thayer <thor.thayer@...ux.intel.com>
> >
> > The Stratix10 peripheral FIFO memories can recover from double
> > bit errors with a warm reset instead of a cold reset.
> > Add the option of a warm reset for peripheral (USB, Ethernet)
> > memories.
> >
> > CPU memories such as SDRAM and OCRAM require a cold reset for
> > DBEs.
> > Filter on whether the error is a SDRAM/OCRAM or a peripheral
> > FIFO memory to determine which reset to use when the warm
> > reset option is configured.
>
> ... so you want to make different SMC calls on each CPU after panic()?
>
>
> > diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
> > index 8816f74a22b4..179601f14b48 100644
> > --- a/drivers/edac/altera_edac.c
> > +++ b/drivers/edac/altera_edac.c
> > @@ -2036,6 +2036,19 @@ static const struct irq_domain_ops a10_eccmgr_ic_ops = {
> >  /* panic routine issues reboot on non-zero panic_timeout */
> >  extern int panic_timeout;
> >
> > +#ifdef CONFIG_EDAC_ALTERA_ARM64_WARM_RESET
> > +/* EL3 SMC call to setup CPUs for warm reset */
> > +void panic_smp_self_stop(void)
> > +{
> > +	struct arm_smccc_res result;
> > +
> > +	__cpu_disable();
> > +	cpu_relax();
> > +	arm_smccc_smc(INTEL_SIP_SMC_ECC_DBE, S10_WARM_RESET_WFI_FLAG,
> > +		      S10_WARM_RESET_WFI_FLAG, 0, 0, 0, 0, 0, &result);

Please use SYSTEM_RESET2 or let us know why it can't be used to understand
the requirement better. There are options to use vendor extentions with
the SYSTEM_RESET2 PSCI command if you really have to. However the mainline
supports only architectural warm reset.

--
Regards,
Sudeep

[1] Documentation/admin-guide/kernel-parameters.txt