[PATCH 4.9 12/14] dmaengine: at_xdma: handle errors of at_xdmac_alloc_desc() correctly

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Michael Walle <michael@walle.cc>

commit 3770d92bd5237d686e49da7b2fb86f53ee6ed259 upstream.

It seems that it is valid to have less than the requested number of
descriptors. But what is not valid and leads to subsequent errors is to
have zero descriptors. In that case, abort the probing.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220526135111.1470926-1-michael@walle.cc
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/dma/at_xdmac.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -1806,6 +1806,11 @@ static int at_xdmac_alloc_chan_resources
 	for (i = 0; i < init_nr_desc_per_channel; i++) {
 		desc = at_xdmac_alloc_desc(chan, GFP_ATOMIC);
 		if (!desc) {
+			if (i == 0) {
+				dev_warn(chan2dev(chan),
+					 "can't allocate any descriptors\n");
+				return -EIO;
+			}
 			dev_warn(chan2dev(chan),
 				"only %d descriptors have been allocated\n", i);
 			break;