We can't use disable_work_sync() if panthor_device_unplug() is called from the reset work or we'll deadlock. Pass a from_reset_work bool to the panthor_device_unplug() function and lower the disable_work_sync() to a disable_work() in that case.
We also add debugfs knobs to simulate this situation. Maybe we should use a separate work and call device_release_driver() instead of calling panthor_device_unplug() directly. This would allow us to actually detach the device from panthor so it can later be re-attached without an explicit unbind/bind or rmmod/modprobe sequence. The problem is, this gets racy if the device is manually unbound/rebound, and it's hard to fix that race, so let's keep this for later. Signed-off-by: Boris Brezillon <[email protected]> --- drivers/gpu/drm/panthor/panthor_device.c | 54 +++++++++++++++++++++++++++++--- drivers/gpu/drm/panthor/panthor_device.h | 10 +++++- drivers/gpu/drm/panthor/panthor_drv.c | 2 +- 3 files changed, 60 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c index 425990369b99..d350bda58bb3 100644 --- a/drivers/gpu/drm/panthor/panthor_device.c +++ b/drivers/gpu/drm/panthor/panthor_device.c @@ -93,7 +93,7 @@ static int panthor_device_stop_before_unplug(struct panthor_device *ptdev) return ret; } -void panthor_device_unplug(struct panthor_device *ptdev) +void panthor_device_unplug(struct panthor_device *ptdev, bool from_reset_work) { int ret; @@ -121,7 +121,10 @@ void panthor_device_unplug(struct panthor_device *ptdev) drm_dev_unplug(&ptdev->base); /* Make sure we're not interrupted by resets while we're unplugging. */ - disable_work_sync(&ptdev->reset.work); + if (!from_reset_work) + disable_work_sync(&ptdev->reset.work); + else + disable_work(&ptdev->reset.work); /* Do anything we can to stop the HW. If we can't guarantee that the HW * is fully stopped, we also can't guarantee the resources it had access @@ -189,13 +192,16 @@ static void panthor_device_reset_work(struct work_struct *work) panthor_hw_soft_reset(ptdev); panthor_hw_l2_power_on(ptdev); panthor_mmu_post_reset(ptdev); - ret = panthor_fw_post_reset(ptdev); + if (ptdev->reset.fake_failure) + ret = -EIO; + else + ret = panthor_fw_post_reset(ptdev); atomic_set(&ptdev->reset.pending, 0); panthor_sched_post_reset(ptdev, ret != 0); drm_dev_exit(cookie); if (ret) { - panthor_device_unplug(ptdev); + panthor_device_unplug(ptdev, true); drm_err(&ptdev->base, "Failed to boot MCU after reset, making device unusable."); } } @@ -694,6 +700,40 @@ DEFINE_DEBUGFS_ATTRIBUTE(panthor_device_fake_unplug_failure_fops, panthor_device_fake_unplug_failure_get, panthor_device_fake_unplug_failure_set, "%llu\n"); +static int panthor_device_fake_fw_reset_failure_get(void *data, u64 *val) +{ + struct panthor_device *ptdev = data; + + *val = ptdev->reset.fake_failure ? 1 : 0; + return 0; +} + +static int panthor_device_fake_fw_reset_failure_set(void *data, u64 val) +{ + struct panthor_device *ptdev = data; + + ptdev->reset.fake_failure = val ? true : false; + return 0; +} + +DEFINE_DEBUGFS_ATTRIBUTE(panthor_device_fake_fw_reset_failure_fops, + panthor_device_fake_fw_reset_failure_get, + panthor_device_fake_fw_reset_failure_set, "%llu\n"); + +static ssize_t panthor_device_reset_file_write(struct file *file, + const char __user *, size_t size, + loff_t *) +{ + struct panthor_device *ptdev = file_inode(file)->i_private; + + panthor_device_schedule_reset(ptdev); + return size; +} + +static const struct debugfs_short_fops panthor_device_reset_fops = { + .write = panthor_device_reset_file_write, +}; + void panthor_device_debugfs_init(struct drm_minor *minor) { struct panthor_device *ptdev = container_of(minor->dev, struct panthor_device, base); @@ -701,6 +741,12 @@ void panthor_device_debugfs_init(struct drm_minor *minor) debugfs_create_file("fake_unplug_failure", 0644, minor->debugfs_root, ptdev, &panthor_device_fake_unplug_failure_fops); + debugfs_create_file("fake_fw_reset_failure", 0644, + minor->debugfs_root, ptdev, + &panthor_device_fake_fw_reset_failure_fops); + debugfs_create_file("reset", 0200, + minor->debugfs_root, ptdev, + &panthor_device_reset_fops); panthor_mmu_debugfs_init(minor); panthor_gem_debugfs_init(minor); } diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h index f960109f4b5b..7d3db80fdfb6 100644 --- a/drivers/gpu/drm/panthor/panthor_device.h +++ b/drivers/gpu/drm/panthor/panthor_device.h @@ -310,6 +310,14 @@ struct panthor_device { * all FW sections to make sure we start from a fresh state. */ bool fast; + + /** + * @fake_failure: When true, pretend the FW boot in the reset path failed. + * + * This is important to check that we're doing the right thing in this very + * unlikely case. + */ + bool fake_failure; } reset; /** @pm: Power management related data. */ @@ -398,7 +406,7 @@ struct panthor_file { }; int panthor_device_init(struct panthor_device *ptdev); -void panthor_device_unplug(struct panthor_device *ptdev); +void panthor_device_unplug(struct panthor_device *ptdev, bool from_reset_work); /** * panthor_device_schedule_reset() - Schedules a reset operation diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c index 924a7ecd3733..730f7996985c 100644 --- a/drivers/gpu/drm/panthor/panthor_drv.c +++ b/drivers/gpu/drm/panthor/panthor_drv.c @@ -1827,7 +1827,7 @@ static void panthor_remove(struct platform_device *pdev) { struct panthor_device *ptdev = platform_get_drvdata(pdev); - panthor_device_unplug(ptdev); + panthor_device_unplug(ptdev, false); } static ssize_t profiling_show(struct device *dev, -- 2.55.0
