From: Paul Cercueil <paul@crapouillou.net>
To: Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>
Cc: list@opendingux.net, dmaengine@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mips@vger.kernel.org, Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH v2 3/6] dmaengine: jz4780: Work around hardware bug on JZ4760 SoCs
Date: Mon, 6 Dec 2021 17:42:56 +0000 [thread overview]
Message-ID: <20211206174259.68133-4-paul@crapouillou.net> (raw)
In-Reply-To: <20211206174259.68133-1-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 96701dedcac8..d63753a56541 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -938,6 +938,14 @@ 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;
--
2.33.0
next prev parent reply other threads:[~2021-12-06 17:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 17:42 [PATCH v2 0/6] dmaengine: jz4780: Driver updates v2 Paul Cercueil
2021-12-06 17:42 ` [PATCH v2 1/6] dt-bindings: dma: ingenic: Add compatible strings for MDMA and BDMA Paul Cercueil
2021-12-06 17:42 ` [PATCH v2 2/6] dt-bindings: dma: ingenic: Support #dma-cells = <3> Paul Cercueil
2021-12-06 17:42 ` Paul Cercueil [this message]
2021-12-06 17:42 ` [PATCH v2 4/6] dmaengine: jz4780: Add support for the MDMA and BDMA in the JZ4760(B) Paul Cercueil
2021-12-06 17:42 ` [PATCH v2 5/6] dmaengine: jz4780: Replace uint32_t with u32 Paul Cercueil
2021-12-06 17:42 ` [PATCH v2 6/6] dmaengine: jz4780: Support bidirectional I/O on one channel Paul Cercueil
2021-12-13 6:22 ` [PATCH v2 0/6] dmaengine: jz4780: Driver updates v2 Vinod Koul
2021-12-13 14:43 ` Paul Cercueil
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