Commit ec62d37d authored by Boris Brezillon's avatar Boris Brezillon
Browse files

drm/panthor: Fix the fast-reset logic 



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.

v3:
- No changes

v2:
- Add R-b

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211075419.2333731-6-boris.brezillon@collabora.com
parent 303e9e98

drivers/gpu/drm/panthor/panthor_device.c

+24 −8
Original line number Diff line number Diff line
@@ -435,6 +435,22 @@ 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);
@@ -461,16 +477,16 @@ 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)

drivers/gpu/drm/panthor/panthor_device.h

+11 −0
Original line number Diff line number Diff line
@@ -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. */

drivers/gpu/drm/panthor/panthor_fw.c

+12 −42
Original line number Diff line number Diff line
@@ -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);
@@ -1100,7 +1089,7 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang) 
		gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);

		if (!readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,

					status == MCU_STATUS_HALT, 10, 100000)) {

			ptdev->fw->fast_reset = true;

			ptdev->reset.fast = true;

		} else {

			drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");

		}
@@ -1125,49 +1114,30 @@ 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->reset.fast) {

		/* 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.

		 */

	if (ptdev->fw->fast_reset) {

		panthor_reload_fw_sections(ptdev, true);

	} else {

		/* The FW detects 0 -> 1 transitions. Make sure we reset

		 * the HALT bit before the FW is rebooted.

		 * This is not needed on a slow reset because FW sections are

		 * re-initialized.

		 */

		struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);

		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);



		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;

		}

		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);

	}



	/* 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);



	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;

drivers/gpu/drm/panthor/panthor_gpu.c

+6 −5
Original line number Diff line number Diff line
@@ -470,11 +470,12 @@ 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.

	 */

	/* 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);

}