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From 5eb927e238d953d7b471d4c81cb6ba0303dad02c Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 13 Mar 2019 14:19:11 +0000
Subject: [PATCH 379/773] bcm2835-sdhost: Allow for sg entries that cross pages

The dma_complete handling code calculates a virtual address for a page
then adds an offset, but if the offset is more than a page and HIGHMEM
is in use then the summed address could be in an unmapped (or just
incorrect) page.

The upstream SDHOST driver allows for this possibility - copy the code
that does so.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
 drivers/mmc/host/bcm2835-sdhost.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/mmc/host/bcm2835-sdhost.c
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -543,6 +543,11 @@ static void bcm2835_sdhost_dma_complete(
 		void *page;
 		u32 *buf;
 
+		if (host->drain_offset & PAGE_MASK) {
+			host->drain_page += host->drain_offset >> PAGE_SHIFT;
+			host->drain_offset &= ~PAGE_MASK;
+		}
+
 		page = kmap_atomic(host->drain_page);
 		buf = page + host->drain_offset;