From 4155ad9aac9474610038b525da9eec8ad9afbc12 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Fri, 14 Feb 2020 16:40:27 +0900
Subject: [PATCH] mmc: sdhci: fix missing cache invalidation after reading by
 DMA

This driver currently performs cache operation before the DMA start,
but does nothing after the DMA completion.

When reading data by DMA, the cache invalidation is needed also after
finishing the DMA transfer. Otherwise, the CPU might read data from
the cache instead of from the main memory when speculative memory read
or memory prefetch occurs.

Instead of calling the cache operation directly, this commit adds
dma_unmap_single(), which performs cache invalidation internally,
but drivers do not need which operation is being run.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
 drivers/mmc/sdhci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 77a88bc043..9b7c5f8f68 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -215,6 +215,10 @@ static int sdhci_transfer_data(struct sdhci_host *host, struct mmc_data *data)
 			return -ETIMEDOUT;
 		}
 	} while (!(stat & SDHCI_INT_DATA_END));
+
+	dma_unmap_single(host->start_addr, data->blocks * data->blocksize,
+			 mmc_get_dma_dir(data));
+
 	return 0;
 }
 
-- 
2.39.5