From fb16a3835107c469433a71341d198c298449ff4d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 4 Sep 2018 17:58:54 +0200
Subject: [PATCH] staging: bcm2835-audio: Use coherent device buffers
Git-commit: fb16a3835107c469433a71341d198c298449ff4d
Patch-mainline: v4.20-rc1
References: FATE#324827

The memory access to the pages allocated with
SNDRV_DMA_TYPE_CONTINUOUS are basically non-coherent, and it becomes a
problem when a process accesses via mmap.

For the more consistent access, use the device coherent memory, just
by replacing the call pattern in the allocator helpers.

The only point we need to be careful for is the device object passed
there; since bcm2835-audio driver creates fake devices and each card
is created on top of that, we need to pass its parent device as the
real device object.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
@@ -345,8 +345,8 @@ int snd_bcm2835_new_pcm(struct bcm2835_c
 
 	/* pre-allocation of buffers */
 	/* NOTE: this may fail */
-	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-					      snd_dma_continuous_data(GFP_KERNEL),
+	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
+					      chip->card->dev->parent,
 					      snd_bcm2835_playback_hw.buffer_bytes_max,
 					      snd_bcm2835_playback_hw.buffer_bytes_max);
 
@@ -371,8 +371,8 @@ int snd_bcm2835_new_spdif_pcm(struct bcm
 
 	/* pre-allocation of buffers */
 	/* NOTE: this may fail */
-	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-		snd_dma_continuous_data(GFP_KERNEL),
+	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
+		chip->card->dev->parent,
 		snd_bcm2835_playback_spdif_hw.buffer_bytes_max, snd_bcm2835_playback_spdif_hw.buffer_bytes_max);
 
 	return 0;
@@ -404,8 +404,8 @@ int snd_bcm2835_new_simple_pcm(struct bc
 
 	snd_pcm_lib_preallocate_pages_for_all(
 		pcm,
-		SNDRV_DMA_TYPE_CONTINUOUS,
-		snd_dma_continuous_data(GFP_KERNEL),
+		SNDRV_DMA_TYPE_DEV,
+		chip->card->dev->parent,
 		snd_bcm2835_playback_hw.buffer_bytes_max,
 		snd_bcm2835_playback_hw.buffer_bytes_max);