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From: Paul Cercueil <paul@crapouillou.net>
To: Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>
Cc: dmaengine@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	list@opendingux.net, Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH 2/3] dma: jz4780: Work around hardware bug on JZ4760 SoCs
Date: Sun, 18 Jul 2021 13:20:23 +0100	[thread overview]
Message-ID: <20210718122024.204907-2-paul@crapouillou.net> (raw)
In-Reply-To: <20210718122024.204907-1-paul@crapouillou.net>

The JZ4760 SoC has a hardware problem with chan0 not enabling properly
if it's enabled before chan1, after a reset (works fine afterwards).
This is worked around in the probe function by just enabling then
disabling chan1.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/dma/dma-jz4780.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index ebee94dbd630..d71bc7235959 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -937,6 +937,14 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 		jzchan->vchan.desc_free = jz4780_dma_desc_free;
 	}
 
+	/*
+	 * On JZ4760, chan0 won't enable properly the first time.
+	 * Enabling then disabling chan1 will magically make chan0 work
+	 * correctly.
+	 */
+	jz4780_dma_chan_enable(jzdma, 1);
+	jz4780_dma_chan_disable(jzdma, 1);
+
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
 		goto err_disable_clk;
-- 
2.30.2


  reply	other threads:[~2021-07-18 12:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-18 12:20 [PATCH 1/3] dt-bindings: dma: ingenic: Add compatible strings for MDMA Paul Cercueil
2021-07-18 12:20 ` Paul Cercueil [this message]
2021-07-18 12:20 ` [PATCH 3/3] dma: jz4780: Add support for the MDMA in the JZ4760(B) Paul Cercueil
2021-07-28  7:16   ` Vinod Koul
2021-07-28  8:22     ` Paul Cercueil
2021-07-29 18:41 ` [PATCH 1/3] dt-bindings: dma: ingenic: Add compatible strings for MDMA Rob Herring

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