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Commit 7d370b2c authored by Masahiro Yamada's avatar Masahiro Yamada Committed by Boris Brezillon
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mtd: nand: denali: use non-managed kmalloc() for DMA buffer 

As Russell and Lars stated in the discussion [1], using
devm_k*alloc() with DMA is not a good idea.

Let's use kmalloc (not kzalloc because no need for zero-out).
Also, allocate the buffer as late as possible because it must be
freed for any error that follows.

[1] https://lkml.org/lkml/2017/3/8/693



Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent 997cde2a

drivers/mtd/nand/denali.c

+17 −9
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/mutex.h>

#include <linux/mtd/mtd.h>

#include <linux/module.h>

#include <linux/slab.h>



#include "denali.h"
@@ -1352,13 +1353,6 @@ int denali_init(struct denali_nand_info *denali) 
	if (ret)

		goto disable_irq;



	denali->buf = devm_kzalloc(denali->dev, mtd->writesize + mtd->oobsize,

				   GFP_KERNEL);

	if (!denali->buf) {

		ret = -ENOMEM;

		goto disable_irq;

	}



	if (ioread32(denali->flash_reg + FEATURES) & FEATURES__DMA)

		denali->dma_avail = 1;
@@ -1443,17 +1437,30 @@ int denali_init(struct denali_nand_info *denali) 
	if (ret)

		goto disable_irq;



	/*

	 * This buffer is DMA-mapped by denali_{read,write}_page_raw.  Do not

	 * use devm_kmalloc() because the memory allocated by devm_ does not

	 * guarantee DMA-safe alignment.

	 */

	denali->buf = kmalloc(mtd->writesize + mtd->oobsize, GFP_KERNEL);

	if (!denali->buf) {

		ret = -ENOMEM;

		goto disable_irq;

	}



	ret = nand_scan_tail(mtd);

	if (ret)

		goto disable_irq;

		goto free_buf;



	ret = mtd_device_register(mtd, NULL, 0);

	if (ret) {

		dev_err(denali->dev, "Failed to register MTD: %d\n", ret);

		goto disable_irq;

		goto free_buf;

	}

	return 0;



free_buf:

	kfree(denali->buf);

disable_irq:

	denali_disable_irq(denali);
@@ -1467,6 +1474,7 @@ void denali_remove(struct denali_nand_info *denali) 
	struct mtd_info *mtd = nand_to_mtd(&denali->nand);



	nand_release(mtd);

	kfree(denali->buf);

	denali_disable_irq(denali);

}

EXPORT_SYMBOL(denali_remove);