[PATCH 1/7] mmc: davinci_mmc: Map the virtual page for PIO

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Use kmap_local_page() instead of sg_virt() to obtain a page
from the scatterlist: sg_virt() will not perform bounce
buffering if the page happens to be located in high memory,
which the driver may or may not be using.

Suggested-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/linux-mmc/20240122073423.GA25859@xxxxxx/
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
 drivers/mmc/host/davinci_mmc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index ee3b1a4e0848..4e9f96b1caf3 100644
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -216,7 +216,7 @@ static irqreturn_t mmc_davinci_irq(int irq, void *dev_id);
 static void mmc_davinci_sg_to_buf(struct mmc_davinci_host *host)
 {
 	host->buffer_bytes_left = sg_dma_len(host->sg);
-	host->buffer = sg_virt(host->sg);
+	host->buffer = kmap_local_page(sg_page(host->sg));
 	if (host->buffer_bytes_left > host->bytes_left)
 		host->buffer_bytes_left = host->bytes_left;
 }
@@ -261,7 +261,13 @@ static void davinci_fifo_data_trans(struct mmc_davinci_host *host,
 			p = p + (n & 3);
 		}
 	}
-	host->buffer = p;
+
+	if (host->buffer_bytes_left == 0) {
+		kunmap_local(host->buffer);
+		host->buffer = NULL;
+	} else {
+		host->buffer = p;
+	}
 }
 
 static void mmc_davinci_start_command(struct mmc_davinci_host *host,

-- 
2.34.1





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