linux-kernel - [PATCH] drm/panthor: Simplify FW fast reset path

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Message-Id: <20241118152152.2921611-1-karunika.choo@arm.com>
Date: Mon, 18 Nov 2024 15:21:52 +0000
From: Karunika Choo <karunika.choo@....com>
To: boris.brezillon@...labora.com
Cc: nd@....com,
	Steven Price <steven.price@....com>,
	Liviu Dudau <liviu.dudau@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/panthor: Simplify FW fast reset path

Stop checking the FW halt_status as MCU_STATUS should be sufficient.
This should make the check for successful FW halt and subsequently
setting fast_reset to true more robust.

We should also clear GLB_REQ.GLB_HALT bit only on post-reset prior
to starting the FW.

Signed-off-by: Karunika Choo <karunika.choo@....com>
---
 drivers/gpu/drm/panthor/panthor_fw.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index ecca5565ce41..6d41089b84ab 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -1098,17 +1098,11 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
 		panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
 		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) &&
-		    glb_iface->output->halt_status == PANTHOR_FW_HALT_OK) {
+					status == MCU_STATUS_HALT, 10, 100000)) {
 			ptdev->fw->fast_reset = true;
 		} else {
 			drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
 		}
-
-		/* The FW detects 0 -> 1 transitions. Make sure we reset
-		 * the HALT bit before the FW is rebooted.
-		 */
-		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
 	}
 
 	panthor_job_irq_suspend(&ptdev->fw->irq);
@@ -1134,6 +1128,11 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
 	 * the FW sections. If it fails, go for a full reset.
 	 */
 	if (ptdev->fw->fast_reset) {
+		/* The FW detects 0 -> 1 transitions. Make sure we reset
+		 * the HALT bit before the FW is rebooted.
+		 */
+		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
+
 		ret = panthor_fw_start(ptdev);
 		if (!ret)
 			goto out;
-- 
2.25.1