mmc: dw_mmc: Fix issue with uninitialized dma_slave_config

stable inclusion
from stable-5.10.65
commit ced0bc748185663a94bc5ae69d7f462a63c66080
bugzilla: 182361 https://gitee.com/openeuler/kernel/issues/I4EH3U

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ced0bc748185663a94bc5ae69d7f462a63c66080

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

[ Upstream commit c3ff0189 ]

Depending on the DMA driver being used, the struct dma_slave_config may
need to be initialized to zero for the unused data.

For example, we have three DMA drivers using src_port_window_size and
dst_port_window_size. If these are left uninitialized, it can cause DMA
failures.

For dw_mmc, this is probably not currently an issue but is still good to
fix though.

Fixes: 3fc7eaef ("mmc: dw_mmc: Add external dma interface support")
Cc: Shawn Lin <shawn.lin@rock-chips.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20210810081644.19353-2-tony@atomide.comSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/mmc/host/dw_mmc.c

@@ -782,6 +782,7 @@ static int dw_mci_edmac_start_dma(struct dw_mci *host,
 	int ret = 0;
 
 	/* Set external dma config: burst size, burst width */
+	memset(&cfg, 0, sizeof(cfg));
 	cfg.dst_addr = host->phy_regs + fifo_offset;
 	cfg.src_addr = cfg.dst_addr;
 	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;