linux-kernel - [PATCH 3/4] drm: xlnx: zynqmp_dpsub: Don't generate vblank in live mode

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Message-ID: <20240112234222.913138-4-anatoliy.klymenko@amd.com>
Date: Fri, 12 Jan 2024 15:42:21 -0800
From: Anatoliy Klymenko <anatoliy.klymenko@....com>
To: <laurent.pinchart@...asonboard.com>, <maarten.lankhorst@...ux.intel.com>,
	<mripard@...nel.org>, <tzimmermann@...e.de>, <airlied@...il.com>,
	<daniel@...ll.ch>, <michal.simek@....com>, <dri-devel@...ts.freedesktop.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/4] drm: xlnx: zynqmp_dpsub: Don't generate vblank in live mode

Filter out status register against interrupts' mask.
Some events are being reported via DP status register, even if
corresponding interrupts have been disabled. Avoid processing
of such events in interrupt handler context.

Signed-off-by: Anatoliy Klymenko <anatoliy.klymenko@....com>
---
 drivers/gpu/drm/xlnx/zynqmp_dp.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index d60b7431603f..571c5dbc97e5 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -1624,8 +1624,16 @@ static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
 	u32 status, mask;
 
 	status = zynqmp_dp_read(dp, ZYNQMP_DP_INT_STATUS);
+	zynqmp_dp_write(dp, ZYNQMP_DP_INT_STATUS, status);
 	mask = zynqmp_dp_read(dp, ZYNQMP_DP_INT_MASK);
-	if (!(status & ~mask))
+
+	/*
+	 * Status register may report some events, which corresponding interrupts
+	 * have been disabled. Filter out those events against interrupts' mask.
+	 */
+	status &= ~mask;
+
+	if (!status)
 		return IRQ_NONE;
 
 	/* dbg for diagnostic, but not much that the driver can do */
@@ -1634,7 +1642,6 @@ static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
 	if (status & ZYNQMP_DP_INT_CHBUF_OVERFLW_MASK)
 		dev_dbg_ratelimited(dp->dev, "overflow interrupt\n");
 
-	zynqmp_dp_write(dp, ZYNQMP_DP_INT_STATUS, status);
 
 	if (status & ZYNQMP_DP_INT_VBLANK_START)
 		zynqmp_dpsub_drm_handle_vblank(dp->dpsub);
-- 
2.25.1