| Message ID | 20210726132223.1661-1-sshivamurthy@micron.com |
|---|---|
| Headers | show |
| Series | Abrupt Shutdown for NVMe SSD | expand |
Hi! > If the shutdown is pwerformed when the platform is running on the > limited backup power supply, some of the devices might not have enough > power to perform a clean shutdown. > > It is necessary to inform the driver about the limited backup power > supply, to allow the driver to decide to perform the minimal required > operation for a fast and clean shutdown. If you can do shutdown that is fast & clean, why not do it always? How fast is normal shutdown vs. fast shutdown? > +#define PM_SUSPEND_FLAG_POWER_LOSS_IMMINENT BIT(3) I believe we should be more concrete here. Like explaining use (did UPS say battery is low? Or does it mean 10 seconds remaining? Or...?) Plus, who sets this flag? Userland? Best regards, Pavel --
On Mon, Jul 26, 2021 at 09:41:46PM +0200, Pavel Machek wrote: > > If the shutdown is pwerformed when the platform is running on the > > limited backup power supply, some of the devices might not have enough > > power to perform a clean shutdown. > > > > It is necessary to inform the driver about the limited backup power > > supply, to allow the driver to decide to perform the minimal required > > operation for a fast and clean shutdown. > > If you can do shutdown that is fast & clean, why not do it always? At least for nvme, I don't think this faster shutdown qualifies as "clean". It's just a little better than removing power without telling the device. Typical implementations take longer to become ready on their next power-on following the abrupt shutdown sequence.
Micron Confidential Hi, > > > On Mon, Jul 26, 2021 at 01:22:21PM +0000, shiva.linuxworks@gmail.com wrote: > > In the platform with a limited backup power supply, devices like NVMe > > SSD does unsafe shutdown. > > > > These two patches address this issue by adding a power loss imminent > > flag. The platform will enable the power loss imminent flag if the > > platform's power is running on the limited backup power supply. During > > the shutdown, the driver checks this information and pwerforms the > > abrupt shutdown. > > I think the pm framework and nvme usage are ok, but you need a platform > specific caller to set the new power loss flag before this should be > considered, otherwise this is just unreachable code. Sure, I will send platform specific caller along with V3. Thanks, Shiva Micron Confidential
From: Shivamurthy Shastri <sshivamurthy@micron.com> In the platform with a limited backup power supply, devices like NVMe SSD does unsafe shutdown. These two patches address this issue by adding a power loss imminent flag. The platform will enable the power loss imminent flag if the platform's power is running on the limited backup power supply. During the shutdown, the driver checks this information and pwerforms the abrupt shutdown. Shivamurthy Shastri (2): PM: introduce power loss imminent nvme: Add abrupt shutdown support drivers/nvme/host/core.c | 7 ++++++- drivers/nvme/host/pci.c | 6 ++++-- include/linux/suspend.h | 28 +++++++++++++++++++++++++--- 3 files changed, 35 insertions(+), 6 deletions(-)