dmaengine: jz4780: Work around hardware bug on JZ4760 SoCs

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>
Link: https://lore.kernel.org/r/20211206174259.68133-4-paul@crapouillou.net
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 96701de..d63753a 100644 (file)
--- 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;