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 and only if we're doing a fast reset, because
the slow reset will re-initialize all FW sections, including the
global interface.

Signed-off-by: Karunika Choo <karunika.choo@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/r/20241119135030.3352939-1-karunika.choo@arm.com
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index ecca5565ce41a7c1cffdc92d82841a349bb28df9..4bc52b1b1a286c7d6654b65e9ce8a7cebf934231 100644 (file)
--- 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 +1128,13 @@ 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.
+                * This is not needed on a slow reset because FW sections are
+                * re-initialized.
+                */
+               panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
+
                ret = panthor_fw_start(ptdev);
                if (!ret)
                        goto out;