The i.MX7ULP Cortex-A7 is under control of Cortex-M4. The i.MX7ULP Linux poweroff and restart rely on rpmsg driver to send a message to Cortex-M4 firmware. Then Cortex-A7 could poweroff or restart by Cortex-M4 to configure the i.MX7ULP power controller properly. However the reboot and restart kernel common code use atomic notifier, see kernel/reboot.c: do_kernel_power_off, do_kernel_restart. Linux 'poweroff' cmd will trigger kernel 'do_kernel_power_off' Linux 'reboot' cmd will trigger kernel 'do_kernel_restart'. Power off and restart are totally different operations and are not complementary. So need to make sure the mailbox be changed to non-blocking mode in SYS_OFF_MODE_POWER_OFF_PREPARE and SYS_OFF_MODE_RESTART_PREPARE stage. Otherwise with blocking tx mailbox, there will be kernel dump, because of blocking mailbox will use wait_for_completion_timeout. In the poweroff or restart case, there is no need to wait, because after M4 got the message, M4 will put A7 to reboot or poweroff. patch 1 is to support non-blocking tx mailbox channel patch 2 is to switch to non-blocking tx for system poweroff or restart. Signed-off-by: Peng Fan <peng.fan@xxxxxxx> --- Changes in v3: - patch 2: Introduce an flags entry for dcfg and set IMX_RPROC_NEED_SYSTEM_OFF for i.MX7ULP, drop used "struct sys_off_data data" and add comment(per Frank). Drop R-b of patch 2 because of this change. - Patch 1: commit log rewritten and R-b dropped. (Thanks to Daniel). - Update patch 2 commit log and cover-letter to clarify reboot and poweroff are different operations and not complementary (Thanks to Daniel). - Link to v2: https://lore.kernel.org/r/20240719-imx_rproc-v2-0-cd8549aa3f1f@xxxxxxx Changes in v2: - Separated patch 5,6 from v1 - Update commit patch 1 with adding "No functional changes" - Link to v1: https://lore.kernel.org/r/20240712-imx_rproc-v1-0-7bcf6732d328@xxxxxxx --- Peng Fan (2): remoteproc: imx_rproc: Allow setting of the mailbox transmit mode remoteproc: imx_rproc: Add support for poweroff and reboot drivers/remoteproc/imx_rproc.c | 54 +++++++++++++++++++++++++++++++++++++----- drivers/remoteproc/imx_rproc.h | 4 ++++ 2 files changed, 52 insertions(+), 6 deletions(-) --- base-commit: 33a32de2d79c051f27ed57c4ac90cdb406f91928 change-id: 20240712-imx_rproc-25f3ab753c58 Best regards, -- Peng Fan <peng.fan@xxxxxxx>
