dmaengine: at_xdma: handle errors of at_xdmac_alloc_desc() correctly

stable inclusion
from stable-v5.10.130
commit 1be247db203ed5cdd1bbd2c2588cef2185600531
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YRJO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1be247db203ed5cdd1bbd2c2588cef2185600531

--------------------------------

commit 3770d92b 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: e1f7c9ee ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: NMichael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220526135111.1470926-1-michael@walle.ccSigned-off-by: NVinod Koul <vkoul@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

drivers/dma/at_xdmac.c

@@ -1838,6 +1838,11 @@ static int at_xdmac_alloc_chan_resources(struct dma_chan *chan)
 	for (i = 0; i < init_nr_desc_per_channel; i++) {
 		desc = at_xdmac_alloc_desc(chan, GFP_KERNEL);
 		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;