[v3,0/2] remoteproc: imx_rproc: support non-blocking tx for i.MX7ULP

Message

Peng Fan (OSS) Aug. 22, 2024, 1:48 p.m. UTC

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 <[e-mail]>
---
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/[e-mail]

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/[e-mail]

---
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,

Comments

Mathieu Poirier Aug. 26, 2024, 3:31 p.m. UTC | #1

On Thu, Aug 22, 2024 at 09:48:48PM +0800, Peng Fan (OSS) wrote:
> 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 <[e-mail]>
> ---
> 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/[e-mail]
> 
> 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/[e-mail]
> 
> ---
> 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(-)

I have applied this set.

Thanks,
Mathieu

> ---
> base-commit: 33a32de2d79c051f27ed57c4ac90cdb406f91928
> change-id: 20240712-imx_rproc-25f3ab753c58
> 
> Best regards,
> -- 
> Peng Fan <[e-mail]>
>