From: Devarsh Thakkar <devarsht@ti.com>

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]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/tidss/tidss_dispc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 99a1138f3e69..515f82e8a0a5 100644
--- 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 dispc_device *dispc, dispc_irq_t mask)
 {
 	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 dispc_device *dispc, dispc_irq_t mask)
 
 	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);
 }
@@ -837,7 +840,7 @@ static void dispc_k3_set_irqenable(struct dispc_device *dispc,
 
 	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) {
@@ -862,6 +865,9 @@ static void dispc_k3_set_irqenable(struct dispc_device *dispc,
 	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);
 }

-- 
2.43.0

On 10/21/24 19:37, Tomi Valkeinen wrote:
> From: Devarsh Thakkar <devarsht@ti.com>
> 
> 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]
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---

Reviewed-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>

Regards
Aradhya

[...]

On Mon, Oct 21, 2024 at 10:08 AM Tomi Valkeinen
<tomi.valkeinen@ideasonboard.com> wrote:
>
> From: Devarsh Thakkar <devarsht@ti.com>
>
> 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]
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Thanks for the updates. They look pretty similar to the changes I
proposed and thus look good to me.
Reviewed-by: Jonathan Cormier <jcormier@criticallink.com>
Tested an equivalent patch for several weeks.
Tested-by: Jonathan Cormier <jcormier@criticallink.com>
> ---
>  drivers/gpu/drm/tidss/tidss_dispc.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
> index 99a1138f3e69..515f82e8a0a5 100644
> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c



-- 
Jonathan Cormier
Software Engineer

Voice:  315.425.4045 x222



http://www.CriticalLink.com
6712 Brooklawn Parkway, Syracuse, NY 13211