linux-kernel - [PATCH v6 8/8] drm/bridge: cdns-mhdp8546: Fix the interrupt enable/disable

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Date:   Tue, 9 May 2023 15:00:36 +0530
From:   Aradhya Bhatia <a-bhatia1@...com>
To:     Tomi Valkeinen <tomba@...nel.org>, Jyri Sarha <jyri.sarha@....fi>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Rahul T R <r-ravikumar@...com>,
        Swapnil Jakhade <sjakhade@...ence.com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Francesco Dolcini <francesco@...cini.it>
CC:     DRI Development List <dri-devel@...ts.freedesktop.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>,
        Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jayesh Choudhary <j-choudhary@...com>,
        Aradhya Bhatia <a-bhatia1@...com>
Subject: [PATCH v6 8/8] drm/bridge: cdns-mhdp8546: Fix the interrupt enable/disable

From: Nikhil Devshatwar <nikhil.nd@...com>

When removing the tidss driver, there is a warning reported by
kernel about an unhandled interrupt for mhdp driver.

[   43.238895] irq 31: nobody cared (try booting with the "irqpoll" option)
... [snipped backtrace]
[   43.330735] handlers:
[   43.333020] [<000000005367c4f9>] irq_default_primary_handler threaded [<000000007e02b601>]
cdns_mhdp_irq_handler [cdns_mhdp8546]
[   43.344607] Disabling IRQ #31

This happens because as part of cdns_mhdp_bridge_hpd_disable, driver tries
to disable the interrupts. While disabling the SW_EVENT interrupts,
it accidentally enables the MBOX interrupts, which are not handled by
the driver.

Fix this with a read-modify-write to update only required bits.
Use the enable / disable function as required in other places.

Signed-off-by: Nikhil Devshatwar <nikhil.nd@...com>
Reviewed-by: Swapnil Jakhade <sjakhade@...ence.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...com>
---

Notes:
    changes from v2:
    * Fix the interrupt enable logic at other places in code
    * Reorder functions so that they can be used earlier in the program

    changes from v5:
    * Manual rebase to linux-next.

 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 44 +++++++++----------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index a677b1267525..66a771b140bc 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -54,6 +54,26 @@
 #include "cdns-mhdp8546-hdcp.h"
 #include "cdns-mhdp8546-j721e.h"
 
+static void cdns_mhdp_bridge_hpd_enable(struct drm_bridge *bridge)
+{
+	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
+
+	/* Enable SW event interrupts */
+	if (mhdp->bridge_attached)
+		writel(readl(mhdp->regs + CDNS_APB_INT_MASK) &
+		       ~CDNS_APB_INT_MASK_SW_EVENT_INT,
+		       mhdp->regs + CDNS_APB_INT_MASK);
+}
+
+static void cdns_mhdp_bridge_hpd_disable(struct drm_bridge *bridge)
+{
+	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
+
+	writel(readl(mhdp->regs + CDNS_APB_INT_MASK) |
+	       CDNS_APB_INT_MASK_SW_EVENT_INT,
+	       mhdp->regs + CDNS_APB_INT_MASK);
+}
+
 static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp)
 {
 	int ret, empty;
@@ -749,9 +769,7 @@ static int cdns_mhdp_fw_activate(const struct firmware *fw,
 	 * MHDP_HW_STOPPED happens only due to driver removal when
 	 * bridge should already be detached.
 	 */
-	if (mhdp->bridge_attached)
-		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
-		       mhdp->regs + CDNS_APB_INT_MASK);
+	cdns_mhdp_bridge_hpd_enable(&mhdp->bridge);
 
 	spin_unlock(&mhdp->start_lock);
 
@@ -1740,8 +1758,7 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge,
 
 	/* Enable SW event interrupts */
 	if (hw_ready)
-		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
-		       mhdp->regs + CDNS_APB_INT_MASK);
+		cdns_mhdp_bridge_hpd_enable(bridge);
 
 	return 0;
 aux_unregister:
@@ -2215,23 +2232,6 @@ static struct edid *cdns_mhdp_bridge_get_edid(struct drm_bridge *bridge,
 	return cdns_mhdp_get_edid(mhdp, connector);
 }
 
-static void cdns_mhdp_bridge_hpd_enable(struct drm_bridge *bridge)
-{
-	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
-
-	/* Enable SW event interrupts */
-	if (mhdp->bridge_attached)
-		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
-		       mhdp->regs + CDNS_APB_INT_MASK);
-}
-
-static void cdns_mhdp_bridge_hpd_disable(struct drm_bridge *bridge)
-{
-	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
-
-	writel(CDNS_APB_INT_MASK_SW_EVENT_INT, mhdp->regs + CDNS_APB_INT_MASK);
-}
-
 static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.atomic_enable = cdns_mhdp_atomic_enable,
 	.atomic_disable = cdns_mhdp_atomic_disable,
-- 
2.40.1