mmc: sdio: fix alignment issue in struct sdio_func

Certain 64-bit systems (e.g. Amlogic Meson GX) require buffers to be used for DMA to be 8-byte-aligned. struct sdio_func has an embedded small DMA buffer not meeting this requirement. When testing switching to descriptor chain mode in meson-gx driver SDIO is broken therefore. Fix this by allocating the small DMA buffer separately as kmalloc ensures that the returned memory area is properly aligned for every basic data type. Signed-off-by: Heiner Kallweit <[email protected]> Tested-by: Helmut Klein <[email protected]> Signed-off-by: Ulf Hansson <[email protected]>
opendata26 · Apr 18, 2017 · 5ef1ecf · 5ef1ecf
1 parent 4f7d029
commit 5ef1ecf
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c
@@ -267,7 +267,7 @@ static void sdio_release_func(struct device *dev)
 	sdio_free_func_cis(func);
 
 	kfree(func->info);
-
+	kfree(func->tmpbuf);
 	kfree(func);
 }
 
@@ -282,6 +282,16 @@ struct sdio_func *sdio_alloc_func(struct mmc_card *card)
 	if (!func)
 		return ERR_PTR(-ENOMEM);
 
+	/*
+	 * allocate buffer separately to make sure it's properly aligned for
+	 * DMA usage (incl. 64 bit DMA)
+	 */
+	func->tmpbuf = kmalloc(4, GFP_KERNEL);
+	if (!func->tmpbuf) {
+		kfree(func);
+		return ERR_PTR(-ENOMEM);
+	}
+
 	func->card = card;
 
 	device_initialize(&func->dev);

diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
@@ -53,7 +53,7 @@ struct sdio_func {
 	unsigned int		state;		/* function state */
 #define SDIO_STATE_PRESENT	(1<<0)		/* present in sysfs */
 
-	u8			tmpbuf[4];	/* DMA:able scratch buffer */
+	u8			*tmpbuf;	/* DMA:able scratch buffer */
 
 	unsigned		num_info;	/* number of info strings */
 	const char		**info;		/* info strings */