Instead of setting up a kernel pointer to track the current PIO address,
track the offset in the current page, and do an atomic kmap for the page
while doing the actual PIO operations.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 drivers/mmc/host/omap.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index c60a7625b1fa..0377ac6194a0 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -13,6 +13,7 @@
 
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
@@ -148,7 +149,7 @@ struct mmc_omap_host {
 
        unsigned int            sg_len;
        int                     sg_idx;
-       u16 *                   buffer;
+       u32                     buffer_offset;
        u32                     buffer_bytes_left;
        u32                     total_bytes_left;
 
@@ -649,7 +650,7 @@ mmc_omap_sg_to_buf(struct mmc_omap_host *host)
 
        sg = host->data->sg + host->sg_idx;
        host->buffer_bytes_left = sg->length;
-       host->buffer = sg_virt(sg);
+       host->buffer_offset = sg->offset;
        if (host->buffer_bytes_left > host->total_bytes_left)
                host->buffer_bytes_left = host->total_bytes_left;
 }
@@ -666,7 +667,9 @@ mmc_omap_clk_timer(struct timer_list *t)
 static void
 mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 {
+       struct scatterlist *sg = host->data->sg + host->sg_idx;
        int n, nwords;
+       void *p;
 
        if (host->buffer_bytes_left == 0) {
                host->sg_idx++;
@@ -684,15 +687,17 @@ mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
        host->total_bytes_left -= n;
        host->data->bytes_xfered += n;
 
+       p = kmap_atomic(sg_page(sg));
        if (write) {
                __raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA),
-                             host->buffer, nwords);
+                             p + host->buffer_offset, nwords);
        } else {
                __raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA),
-                            host->buffer, nwords);
+                            p + host->buffer_offset, nwords);
        }
+       kunmap_atomic(p);
 
-       host->buffer += nwords;
+       host->buffer_offset += nwords;
 }
 
 #ifdef CONFIG_MMC_DEBUG
-- 
2.20.1

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