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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Daniel=20Gonz=C3=A1lez=20Cabanelas?= <dgcbueu@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 142/218] media: cx88-mpeg: clear interrupt status register before streaming video
Date:   Mon, 18 Apr 2022 14:13:28 +0200
Message-Id: <20220418121203.653850945@linuxfoundation.org>
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From: Daniel González Cabanelas <dgcbueu@gmail.com>

[ Upstream commit 56cb61f70e547e1b0cdfe6ff5a1f1ce6242e6d96 ]

Some cx88 video cards may have transport stream status interrupts set
to 1 from cold start, causing errors like this:

  cx88xx: cx88_print_irqbits: core:irq mpeg  [0x100000] ts_err?*
  cx8802: cx8802_mpeg_irq: mpeg:general errors: 0x00100000

According to CX2388x datasheet, the interrupt status register should be
cleared before enabling IRQs to stream video.

Fix it by clearing the Transport Stream Interrupt Status register.

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/pci/cx88/cx88-mpeg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/pci/cx88/cx88-mpeg.c b/drivers/media/pci/cx88/cx88-mpeg.c
index 245357adbc25..37d4512f3eb8 100644
--- a/drivers/media/pci/cx88/cx88-mpeg.c
+++ b/drivers/media/pci/cx88/cx88-mpeg.c
@@ -175,6 +175,9 @@ int cx8802_start_dma(struct cx8802_dev    *dev,
 	cx_write(MO_TS_GPCNTRL, GP_COUNT_CONTROL_RESET);
 	q->count = 0;
 
+	/* clear interrupt status register */
+	cx_write(MO_TS_INTSTAT,  0x1f1111);
+
 	/* enable irqs */
 	dprintk( 1, "setting the interrupt mask\n" );
 	cx_set(MO_PCI_INTMSK, core->pci_irqmask | PCI_INT_TSINT);
-- 
2.34.1