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From:   Peter Ujfalusi <peter.ujfalusi@ti.com>
To:     <vkoul@kernel.org>, <dan.j.williams@intel.com>
CC:     <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH] dmaengine: dma_request_chan_by_mask() to handle deferred probing
Date:   Wed, 18 Jul 2018 12:29:57 +0300
Message-ID: <20180718092957.1934-1-peter.ujfalusi@ti.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
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If there are no DMA devices registered yet, return with EPROBE_DEFER
similarly to the case when requesting a slave channel.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
 drivers/dma/dmaengine.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index d8fc7b58e506..f62e59e1a264 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -768,8 +768,14 @@ struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
 		return ERR_PTR(-ENODEV);
 
 	chan = __dma_request_channel(mask, NULL, NULL);
-	if (!chan)
-		chan = ERR_PTR(-ENODEV);
+	if (!chan) {
+		mutex_lock(&dma_list_mutex);
+		if (list_empty(&dma_device_list))
+			chan = ERR_PTR(-EPROBE_DEFER);
+		else
+			chan = ERR_PTR(-ENODEV);
+		mutex_unlock(&dma_list_mutex);
+	}
 
 	return chan;
 }
-- 
Peter

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