releases/6.12.16/drm-tidss-clear-the-interrupt-status-for-interrupts-being-disabled.patch

From 361a2ebb5cad211732ec3c5d962de49b21895590 Mon Sep 17 00:00:00 2001
From: Devarsh Thakkar <devarsht@ti.com>
Date: Mon, 21 Oct 2024 17:07:49 +0300
Subject: drm/tidss: Clear the interrupt status for interrupts being disabled

From: Devarsh Thakkar <devarsht@ti.com>

commit 361a2ebb5cad211732ec3c5d962de49b21895590 upstream.

The driver does not touch the irqstatus register when it is disabling
interrupts.  This might cause an interrupt to trigger for an interrupt
that was just disabled.

To fix the issue, clear the irqstatus registers right after disabling
the interrupts.

Fixes: 32a1795f57ee ("drm/tidss: New driver for TI Keystone platform Display SubSystem")
Cc: stable@vger.kernel.org
Reported-by: Jonathan Cormier <jcormier@criticallink.com>
Closes: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1394222/am625-issue-about-tidss-rcu_preempt-self-detected-stall-on-cpu/5424479#5424479
Signed-off-by: Devarsh Thakkar <devarsht@ti.com>
[Tomi: mostly rewrote the patch]
Reviewed-by: Jonathan Cormier <jcormier@criticallink.com>
Tested-by: Jonathan Cormier <jcormier@criticallink.com>
Reviewed-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241021-tidss-irq-fix-v1-5-82ddaec94e4a@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/tidss/tidss_dispc.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -700,7 +700,7 @@ void dispc_k2g_set_irqenable(struct disp
 {
 	dispc_irq_t old_mask = dispc_k2g_read_irqenable(dispc);
 
-	/* clear the irqstatus for newly enabled irqs */
+	/* clear the irqstatus for irqs that will be enabled */
 	dispc_k2g_clear_irqstatus(dispc, (mask ^ old_mask) & mask);
 
 	dispc_k2g_vp_set_irqenable(dispc, 0, mask);
@@ -708,6 +708,9 @@ void dispc_k2g_set_irqenable(struct disp
 
 	dispc_write(dispc, DISPC_IRQENABLE_SET, (1 << 0) | (1 << 7));
 
+	/* clear the irqstatus for irqs that were disabled */
+	dispc_k2g_clear_irqstatus(dispc, (mask ^ old_mask) & old_mask);
+
 	/* flush posted write */
 	dispc_k2g_read_irqenable(dispc);
 }
@@ -839,7 +842,7 @@ static void dispc_k3_set_irqenable(struc
 
 	old_mask = dispc_k3_read_irqenable(dispc);
 
-	/* clear the irqstatus for newly enabled irqs */
+	/* clear the irqstatus for irqs that will be enabled */
 	dispc_k3_clear_irqstatus(dispc, (old_mask ^ mask) & mask);
 
 	for (i = 0; i < dispc->feat->num_vps; ++i) {
@@ -864,6 +867,9 @@ static void dispc_k3_set_irqenable(struc
 	if (main_disable)
 		dispc_write(dispc, DISPC_IRQENABLE_CLR, main_disable);
 
+	/* clear the irqstatus for irqs that were disabled */
+	dispc_k3_clear_irqstatus(dispc, (old_mask ^ mask) & old_mask);
+
 	/* Flush posted writes */
 	dispc_read(dispc, DISPC_IRQENABLE_SET);
 }