On 13/11/2024 15:42, Boris Brezillon wrote:
> If we do a GPU soft-reset, that's no longer fast reset. This also means
> the slow reset fallback doesn't work because the MCU state is only reset
> after a GPU soft-reset.
>
> Let's move the retry logic to panthor_device_resume() to issue a
> soft-reset between the fast and slow attempts, and patch
> panthor_gpu_suspend() to only power-off the L2 when a fast reset is
> requested.
>
> Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
I also don't have a good way of testing this, but it looks right and it
doesn't blow up in the "normal" case, so:
Reviewed-by: Steven Price <steven.pr...@arm.com>
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 32 ++++++++++++----
> drivers/gpu/drm/panthor/panthor_device.h | 11 ++++++
> drivers/gpu/drm/panthor/panthor_fw.c | 48 ++++--------------------
> drivers/gpu/drm/panthor/panthor_gpu.c | 11 +++---
> 4 files changed, 49 insertions(+), 53 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c
> b/drivers/gpu/drm/panthor/panthor_device.c
> index d3276b936141..2b93c56e1319 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -417,6 +417,22 @@ int panthor_device_mmap_io(struct panthor_device *ptdev,
> struct vm_area_struct *
> return 0;
> }
>
> +static int panthor_device_resume_hw_components(struct panthor_device *ptdev)
> +{
> + int ret;
> +
> + panthor_gpu_resume(ptdev);
> + panthor_mmu_resume(ptdev);
> +
> + ret = panthor_fw_resume(ptdev);
> + if (!ret)
> + return 0;
> +
> + panthor_mmu_suspend(ptdev);
> + panthor_gpu_suspend(ptdev);
> + return ret;
> +}
> +
> int panthor_device_resume(struct device *dev)
> {
> struct panthor_device *ptdev = dev_get_drvdata(dev);
> @@ -443,16 +459,16 @@ int panthor_device_resume(struct device *dev)
>
> if (panthor_device_is_initialized(ptdev) &&
> drm_dev_enter(&ptdev->base, &cookie)) {
> - panthor_gpu_resume(ptdev);
> - panthor_mmu_resume(ptdev);
> - ret = panthor_fw_resume(ptdev);
> - if (!drm_WARN_ON(&ptdev->base, ret)) {
> - panthor_sched_resume(ptdev);
> - } else {
> - panthor_mmu_suspend(ptdev);
> - panthor_gpu_suspend(ptdev);
> + ret = panthor_device_resume_hw_components(ptdev);
> + if (ret && ptdev->reset.fast) {
> + drm_err(&ptdev->base, "Fast reset failed, trying a slow
> reset");
> + ptdev->reset.fast = false;
> + ret = panthor_device_resume_hw_components(ptdev);
> }
>
> + if (!ret)
> + panthor_sched_resume(ptdev);
> +
> drm_dev_exit(cookie);
>
> if (ret)
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h
> b/drivers/gpu/drm/panthor/panthor_device.h
> index cc74e99e53f9..cab7ce740ce3 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -157,6 +157,17 @@ struct panthor_device {
>
> /** @pending: Set to true if a reset is pending. */
> atomic_t pending;
> +
> + /**
> + * @fast: True if the post_reset logic can proceed with a fast
> reset.
> + *
> + * A fast reset is just a reset where the driver doesn't reload
> the FW sections.
> + *
> + * Any time the firmware is properly suspended, a fast reset
> can take place.
> + * On the other hand, if the halt operation failed, the driver
> will reload
> + * all FW sections to make sure we start from a fresh state.
> + */
> + bool fast;
> } reset;
>
> /** @pm: Power management related data. */
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c
> b/drivers/gpu/drm/panthor/panthor_fw.c
> index df74750cf1b7..b4fe0de547d1 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -263,17 +263,6 @@ struct panthor_fw {
> /** @booted: True is the FW is booted */
> bool booted;
>
> - /**
> - * @fast_reset: True if the post_reset logic can proceed with a fast
> reset.
> - *
> - * A fast reset is just a reset where the driver doesn't reload the FW
> sections.
> - *
> - * Any time the firmware is properly suspended, a fast reset can take
> place.
> - * On the other hand, if the halt operation failed, the driver will
> reload
> - * all sections to make sure we start from a fresh state.
> - */
> - bool fast_reset;
> -
> /** @irq: Job irq data. */
> struct panthor_irq irq;
> };
> @@ -1090,7 +1079,7 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev,
> bool on_hang)
> /* Make sure we won't be woken up by a ping. */
> cancel_delayed_work_sync(&ptdev->fw->watchdog.ping_work);
>
> - ptdev->fw->fast_reset = false;
> + ptdev->reset.fast = false;
>
> if (!on_hang) {
> struct panthor_fw_global_iface *glb_iface =
> panthor_fw_get_glb_iface(ptdev);
> @@ -1101,7 +1090,7 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev,
> bool on_hang)
> if (!readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,
> status == MCU_STATUS_HALT, 10, 100000)
> &&
> glb_iface->output->halt_status == PANTHOR_FW_HALT_OK) {
> - ptdev->fw->fast_reset = true;
> + ptdev->reset.fast = true;
> } else {
> drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
> }
> @@ -1131,41 +1120,20 @@ int panthor_fw_post_reset(struct panthor_device
> *ptdev)
> if (ret)
> return ret;
>
> - /* If this is a fast reset, try to start the MCU without reloading
> - * the FW sections. If it fails, go for a full reset.
> - */
> - if (ptdev->fw->fast_reset) {
> - ret = panthor_fw_start(ptdev);
> - if (!ret)
> - goto out;
> -
> - /* Forcibly reset the MCU and force a slow reset, so we get a
> - * fresh boot on the next panthor_fw_start() call.
> - */
> - panthor_fw_stop(ptdev);
> - ptdev->fw->fast_reset = false;
> - drm_err(&ptdev->base, "FW fast reset failed, trying a slow
> reset");
> -
> - ret = panthor_vm_flush_all(ptdev->fw->vm);
> - if (ret) {
> - drm_err(&ptdev->base, "FW slow reset failed (couldn't
> flush FW's AS l2cache)");
> - return ret;
> - }
> - }
> -
> - /* Reload all sections, including RO ones. We're not supposed
> - * to end up here anyway, let's just assume the overhead of
> + /* On a slow reset, reload all sections, including RO ones. We're not
> + * supposed to end up here anyway, let's just assume the overhead of
> * reloading everything is acceptable.
> */
> - panthor_reload_fw_sections(ptdev, true);
> + if (!ptdev->reset.fast)
> + panthor_reload_fw_sections(ptdev, true);
>
> ret = panthor_fw_start(ptdev);
> if (ret) {
> - drm_err(&ptdev->base, "FW slow reset failed (couldn't start the
> FW )");
> + drm_err(&ptdev->base, "FW %s reset failed",
> + ptdev->reset.fast ? "fast" : "slow");
> return ret;
> }
>
> -out:
> /* We must re-initialize the global interface even on fast-reset. */
> panthor_fw_init_global_iface(ptdev);
> return 0;
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c
> b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 27702bc62dd6..ce3b68124a0a 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -461,11 +461,12 @@ int panthor_gpu_soft_reset(struct panthor_device *ptdev)
> */
> void panthor_gpu_suspend(struct panthor_device *ptdev)
> {
> - /*
> - * It may be preferable to simply power down the L2, but for now just
> - * soft-reset which will leave the L2 powered down.
> - */
> - panthor_gpu_soft_reset(ptdev);
> + /* On a fast reset, simply power down the L2. */
> + if (!ptdev->reset.fast)
> + panthor_gpu_soft_reset(ptdev);
> + else
> + panthor_gpu_power_off(ptdev, L2, 1, 20000);
> +
> panthor_gpu_irq_suspend(&ptdev->gpu->irq);
> }
>
