From 250dcd11466e06df64b92520e2c56bdae453581b Mon Sep 17 00:00:00 2001
From: Ulf Hansson <ulf.hansson@linaro.org>
Date: Mon, 27 Nov 2017 11:28:50 +0100
Subject: [PATCH] mmc: sdhci: Avoid swiotlb buffer being full

The commit de3ee99b097d ("mmc: Delete bounce buffer handling") deletes the
bounce buffer handling, but also causes the max_req_size for sdhci to be
increased, in case when max_segs == 1. This causes errors for sdhci-pci
Ricoh variant, about the swiotlb buffer to become full.

Fix the issue, by taking IO_TLB_SEGSIZE and IO_TLB_SHIFT into account when
deciding the max_req_size for sdhci.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Fixes: de3ee99b097d ("mmc: Delete bounce buffer handling")
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/host/sdhci.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 2f14334e42df..e9290a3439d5 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -21,6 +21,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/scatterlist.h>
+#include <linux/swiotlb.h>
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
@@ -3650,17 +3651,6 @@ int sdhci_setup_host(struct sdhci_host *host)
 
 	spin_lock_init(&host->lock);
 
-	/*
-	 * Maximum number of segments. Depends on if the hardware
-	 * can do scatter/gather or not.
-	 */
-	if (host->flags & SDHCI_USE_ADMA)
-		mmc->max_segs = SDHCI_MAX_SEGS;
-	else if (host->flags & SDHCI_USE_SDMA)
-		mmc->max_segs = 1;
-	else /* PIO */
-		mmc->max_segs = SDHCI_MAX_SEGS;
-
 	/*
 	 * Maximum number of sectors in one transfer. Limited by SDMA boundary
 	 * size (512KiB). Note some tuning modes impose a 4MiB limit, but this
@@ -3668,6 +3658,24 @@ int sdhci_setup_host(struct sdhci_host *host)
 	 */
 	mmc->max_req_size = 524288;
 
+	/*
+	 * Maximum number of segments. Depends on if the hardware
+	 * can do scatter/gather or not.
+	 */
+	if (host->flags & SDHCI_USE_ADMA) {
+		mmc->max_segs = SDHCI_MAX_SEGS;
+	} else if (host->flags & SDHCI_USE_SDMA) {
+		mmc->max_segs = 1;
+		if (swiotlb_max_segment()) {
+			unsigned int max_req_size = (1 << IO_TLB_SHIFT) *
+						IO_TLB_SEGSIZE;
+			mmc->max_req_size = min(mmc->max_req_size,
+						max_req_size);
+		}
+	} else { /* PIO */
+		mmc->max_segs = SDHCI_MAX_SEGS;
+	}
+
 	/*
 	 * Maximum segment size. Could be one segment with the maximum number
 	 * of bytes. When doing hardware scatter/gather, each entry cannot