Hi Michal, On 15 July 2018 at 23:31, Michal Simek <[email protected]> wrote: > On 16.7.2018 07:20, Simon Glass wrote: >> Hi Michal, >> >> On 13 July 2018 at 03:15, Michal Simek <[email protected]> wrote: >>> The Linux kernel has binding for gpio-restart node. >>> This patch is adding basic support without supporting any optional >>> properties. >>> This driver was tested on Microblaze system where gpio is connected to >>> SoC reset logic. >>> Output value is handled via gpios cells values. >>> >>> In gpio_reboot_request() set_value is writing 1 because >>> dm_gpio_set_value() is capable to changing it when it is ACTIVE_LOW. >>> ... >>> if (desc->flags & GPIOD_ACTIVE_LOW) >>> value = !value; >>> ... >>> >>> Signed-off-by: Michal Simek <[email protected]> >>> --- >>> >>> drivers/sysreset/Kconfig | 6 ++++ >>> drivers/sysreset/Makefile | 1 + >>> drivers/sysreset/sysreset_gpio.c | 59 >>> ++++++++++++++++++++++++++++++++++++++++ >>> 3 files changed, 66 insertions(+) >>> create mode 100644 drivers/sysreset/sysreset_gpio.c >> >> Reviewed-by: Simon Glass <[email protected]> >> >> But please see below. >> >>> >>> diff --git a/drivers/sysreset/Kconfig b/drivers/sysreset/Kconfig >>> index a6d48e8a662c..1e228b97443a 100644 >>> --- a/drivers/sysreset/Kconfig >>> +++ b/drivers/sysreset/Kconfig >>> @@ -15,6 +15,12 @@ config SYSRESET >>> >>> if SYSRESET >>> >>> +config SYSRESET_GPIO >>> + bool "Enable support for GPIO restart driver" >>> + select GPIO >>> + help >>> + Restart support via GPIO pin connected reset logic. >> >> What does this mean? Please expand this to explain what it means. >> >> Also, what is the difference between restart and reset? If there is no >> difference please use the word 'reset'. If there is a difference, >> please explain it here. > > I have taken restart name because this is what it is written Linux kernel. > > Based on this explanation: > https://kb.netgear.com/1001/Defining-Terms-Power-Cycle-Boot-Reboot-Restart-Reset-and-Hard-Reset > > "Unlike a reset which changes something, a restart means to turn > something on, possibly without changing settings. When upgrading > firmware or software you are often asked to restart. A restart would be > probably be used if there were a major change to functionality, while a > reset often just changes settings of existing functionality." >
Perhaps this corresponds to warm and cold reset? I'm not sure. But I don't know of a board which supports resetting without changing anything. At the least the CPU is put back into a start where it can start at its reset vector. This really doesn't make any sense to me. I think we should stick with 'reset' to avoid confusion. By all means add some notes to the uclass header file about what it should mean. We already have enum sysreset_t, so you could define 'restart' there, perhaps? Regards, Simon _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
