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Date:   Wed, 2 May 2018 12:41:32 +0200
From:   Ladislav Michl <ladis@linux-mips.org>
To:     Boris Brezillon <boris.brezillon@bootlin.com>
Cc:     linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Roger Quadros <rogerq@ti.com>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        Tony Lindgren <tony@atomide.com>,
        "H. Nikolaus Schaller" <hns@goldelico.com>,
        Andreas Kemnade <andreas@kemnade.info>
Subject: [PATCH v3] mtd: onenand: omap2: Disable DMA for HIGHMEM buffers
Message-ID: <20180502104132.GA12979@lenoch>
MIME-Version: 1.0
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Content-Disposition: inline
User-Agent: Mutt/1.9.5 (2018-04-13)
Sender: linux-kernel-owner@vger.kernel.org
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dma_map_single does not work for vmalloc-ed buffers,
so disable DMA in this case.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Reported-by: "H. Nikolaus Schaller" <hns@goldelico.com>
Tested-by: "H. Nikolaus Schaller" <hns@goldelico.com>
---
 Changes:
  -v2: Added Tested-by tag, based on v4.17-rc1 (no change in patch itself)
  -v3: Reworded commit log

 drivers/mtd/nand/onenand/omap2.c | 105 +++++++++++--------------------
 1 file changed, 38 insertions(+), 67 deletions(-)

diff --git a/drivers/mtd/nand/onenand/omap2.c b/drivers/mtd/nand/onenand/omap2.c
index 9c159f0dd9a6..321137158ff3 100644
--- a/drivers/mtd/nand/onenand/omap2.c
+++ b/drivers/mtd/nand/onenand/omap2.c
@@ -375,56 +375,42 @@ static int omap2_onenand_read_bufferram(struct mtd_info *mtd, int area,
 {
 	struct omap2_onenand *c = container_of(mtd, struct omap2_onenand, mtd);
 	struct onenand_chip *this = mtd->priv;
-	dma_addr_t dma_src, dma_dst;
-	int bram_offset;
+	struct device *dev = &c->pdev->dev;
 	void *buf = (void *)buffer;
+	dma_addr_t dma_src, dma_dst;
+	int bram_offset, err;
 	size_t xtra;
-	int ret;
 
 	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
-	if (bram_offset & 3 || (size_t)buf & 3 || count < 384)
-		goto out_copy;
-
-	/* panic_write() may be in an interrupt context */
-	if (in_interrupt() || oops_in_progress)
+	/*
+	 * If the buffer address is not DMA-able, len is not long enough to make
+	 * DMA transfers profitable or panic_write() may be in an interrupt
+	 * context fallback to PIO mode.
+	 */
+	if (!virt_addr_valid(buf) || bram_offset & 3 || (size_t)buf & 3 ||
+	    count < 384 || in_interrupt() || oops_in_progress )
 		goto out_copy;
 
-	if (buf >= high_memory) {
-		struct page *p1;
-
-		if (((size_t)buf & PAGE_MASK) !=
-		    ((size_t)(buf + count - 1) & PAGE_MASK))
-			goto out_copy;
-		p1 = vmalloc_to_page(buf);
-		if (!p1)
-			goto out_copy;
-		buf = page_address(p1) + ((size_t)buf & ~PAGE_MASK);
-	}
-
 	xtra = count & 3;
 	if (xtra) {
 		count -= xtra;
 		memcpy(buf + count, this->base + bram_offset + count, xtra);
 	}
 
+	dma_dst = dma_map_single(dev, buf, count, DMA_FROM_DEVICE);
 	dma_src = c->phys_base + bram_offset;
-	dma_dst = dma_map_single(&c->pdev->dev, buf, count, DMA_FROM_DEVICE);
-	if (dma_mapping_error(&c->pdev->dev, dma_dst)) {
-		dev_err(&c->pdev->dev,
-			"Couldn't DMA map a %d byte buffer\n",
-			count);
-		goto out_copy;
-	}
 
-	ret = omap2_onenand_dma_transfer(c, dma_src, dma_dst, count);
-	dma_unmap_single(&c->pdev->dev, dma_dst, count, DMA_FROM_DEVICE);
-
-	if (ret) {
-		dev_err(&c->pdev->dev, "timeout waiting for DMA\n");
+	if (dma_mapping_error(dev, dma_dst)) {
+		dev_err(dev, "Couldn't DMA map a %d byte buffer\n", count);
 		goto out_copy;
 	}
 
-	return 0;
+	err = omap2_onenand_dma_transfer(c, dma_src, dma_dst, count);
+	dma_unmap_single(dev, dma_dst, count, DMA_FROM_DEVICE);
+	if (!err)
+		return 0;
+
+	dev_err(dev, "timeout waiting for DMA\n");
 
 out_copy:
 	memcpy(buf, this->base + bram_offset, count);
@@ -437,49 +423,34 @@ static int omap2_onenand_write_bufferram(struct mtd_info *mtd, int area,
 {
 	struct omap2_onenand *c = container_of(mtd, struct omap2_onenand, mtd);
 	struct onenand_chip *this = mtd->priv;
-	dma_addr_t dma_src, dma_dst;
-	int bram_offset;
+	struct device *dev = &c->pdev->dev;
 	void *buf = (void *)buffer;
-	int ret;
+	dma_addr_t dma_src, dma_dst;
+	int bram_offset, err;
 
 	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
-	if (bram_offset & 3 || (size_t)buf & 3 || count < 384)
-		goto out_copy;
-
-	/* panic_write() may be in an interrupt context */
-	if (in_interrupt() || oops_in_progress)
+	/*
+	 * If the buffer address is not DMA-able, len is not long enough to make
+	 * DMA transfers profitable or panic_write() may be in an interrupt
+	 * context fallback to PIO mode.
+	 */
+	if (!virt_addr_valid(buf) || bram_offset & 3 || (size_t)buf & 3 ||
+	    count < 384 || in_interrupt() || oops_in_progress )
 		goto out_copy;
 
-	if (buf >= high_memory) {
-		struct page *p1;
-
-		if (((size_t)buf & PAGE_MASK) !=
-		    ((size_t)(buf + count - 1) & PAGE_MASK))
-			goto out_copy;
-		p1 = vmalloc_to_page(buf);
-		if (!p1)
-			goto out_copy;
-		buf = page_address(p1) + ((size_t)buf & ~PAGE_MASK);
-	}
-
-	dma_src = dma_map_single(&c->pdev->dev, buf, count, DMA_TO_DEVICE);
+	dma_src = dma_map_single(dev, buf, count, DMA_TO_DEVICE);
 	dma_dst = c->phys_base + bram_offset;
-	if (dma_mapping_error(&c->pdev->dev, dma_src)) {
-		dev_err(&c->pdev->dev,
-			"Couldn't DMA map a %d byte buffer\n",
-			count);
-		return -1;
-	}
-
-	ret = omap2_onenand_dma_transfer(c, dma_src, dma_dst, count);
-	dma_unmap_single(&c->pdev->dev, dma_src, count, DMA_TO_DEVICE);
-
-	if (ret) {
-		dev_err(&c->pdev->dev, "timeout waiting for DMA\n");
+	if (dma_mapping_error(dev, dma_src)) {
+		dev_err(dev, "Couldn't DMA map a %d byte buffer\n", count);
 		goto out_copy;
 	}
 
-	return 0;
+	err = omap2_onenand_dma_transfer(c, dma_src, dma_dst, count);
+	dma_unmap_page(dev, dma_src, count, DMA_TO_DEVICE);
+	if (!err)
+		return 0;
+
+	dev_err(dev, "timeout waiting for DMA\n");
 
 out_copy:
 	memcpy(this->base + bram_offset, buf, count);
-- 
2.17.0