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Message-ID: <20190412095528.GA12424@e107155-lin> Date: Fri, 12 Apr 2019 10:55:28 +0100 From: Sudeep Holla <sudeep.holla@....com> To: Aaro Koskinen <aaro.koskinen@....fi> Cc: "Koskinen, Aaro (Nokia - FI/Espoo)" <aaro.koskinen@...ia.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Florian Fainelli <f.fainelli@...il.com>, Michal Simek <michal.simek@...inx.com>, Mark Rutland <mark.rutland@....com>, Lorenzo Pieralisi <lorenzo.pieralisi@....com> Subject: Re: [RESEND][PATCH v2] firmware/psci: add support for SYSTEM_RESET2 On Thu, Apr 11, 2019 at 09:26:37PM +0300, Aaro Koskinen wrote: > Hi, > > On Thu, Apr 11, 2019 at 05:49:36PM +0100, Sudeep Holla wrote: > > On Thu, Apr 11, 2019 at 11:42:28AM +0000, Koskinen, Aaro (Nokia - FI/Espoo) wrote: > > > From: Sudeep Holla [sudeep.holla@....com]: > > > > static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd) > > > > { > > > > + if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) && > > > > > > I would omit the REBOOT_SOFT here. > > > > I included REBOOT_SOFT for 2 reasons: > > 1. drivers/firmware/efi/reboot.c - efi_reboot treats WARM and SOFT reboots same > > 2. If the vendors specific reboots are added and handled in EFI, I assume it > > will be categorised under REBOOT_SOFT. > > > > If that's wrong I can drop REBOOT_SOFT. > > Not a big issue, but it's just unclear what SOFT means. WARM at least maps > nicely to the PSCI spec. > OK, I will keep it for now. > > > > + psci_system_reset2_supported) > > > > + /* > > > > + * reset_type[31] = 0 (architectural) > > > > + * reset_type[30:0] = 0 (SYSTEM_WARM_RESET) > > > > + * cookie = 0 (ignored by the implementation) > > > > + */ > > > > + invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0); > > > > + > > > > invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0); > > > > > > Use else here, so that we fall back to system halt if SYSTEM_RESET2 fails. > > > > Will that not change current behaviour ? IOW, is that expected behaviour ? > > I am not sure if halt can be prefer over cold reboot in absence of warm/soft > > reboot when the system is request to reboot. From PSCI perspective, since > > SYSTEM_RESET is mandatory I prefer that unless Linux has any restriction > > on this behaviour. > > Hmm, so does it mean that even if firmware tells that SYSTEM_RESET2 > is implemented it does not imply that SYSTEM_WARM_RESET is > available? I.e. the firmware could choose to implement only some > vendor-specific resets but not architectural ones. In that case, could > we fall back to cold reset only if NOT_SUPPORTED is returned? My point > is that if the warm reset fails unexpectedly, we should halt the system > like we do if the cold reset fails. > OK, I understood. Sorry I was under the assumption that architectural reset was mandatory if SYSTEM_RESET2 is implemented. I checked the PSCI specification and I am wrong. So I am happy to add else as per your suggestion. -- Regards, Sudeep
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