linux-kernel - [PATCH 3.4 015/176] ALSA: hda - Limit 40bit DMA for AMD HDMI controllers

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Message-Id: <1428569224-23820-15-git-send-email-lizf@kernel.org>
Date:	Thu,  9 Apr 2015 16:44:23 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 015/176] ALSA: hda - Limit 40bit DMA for AMD HDMI controllers

From: Takashi Iwai <tiwai@...e.de>

3.4.107-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 413cbf469a19e7662ba5025695bf5a573927105a upstream.

AMD/ATI HDMI controller chip models, we already have a filter to lower
to 32bit DMA, but the rest are supposed to be working with 64bit
although the hardware doesn't really work with 63bit but only with 40
or 48bit DMA.  In this patch, we take 40bit DMA for safety for the
AMD/ATI controllers as the graphics drivers does.

Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
[lizf: Backported to 3.4:
 - adjust context
 - s/AZX_GCAP_640K/ICH6_GCAP_64OK]
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 sound/pci/hda/hda_intel.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 33e538f..f461737 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2685,6 +2685,7 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci,
 	struct azx *chip;
 	int i, err;
 	unsigned short gcap;
+	unsigned int dma_bits = 64;
 	static struct snd_device_ops ops = {
 		.dev_free = azx_dev_free,
 	};
@@ -2780,9 +2781,14 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci,
 	gcap = azx_readw(chip, GCAP);
 	snd_printdd(SFX "chipset global capabilities = 0x%x\n", gcap);
 
+	/* AMD devices support 40 or 48bit DMA, take the safe one */
+	if (chip->pci->vendor == PCI_VENDOR_ID_AMD)
+		dma_bits = 40;
+
 	/* disable SB600 64bit support for safety */
 	if (chip->pci->vendor == PCI_VENDOR_ID_ATI) {
 		struct pci_dev *p_smbus;
+		dma_bits = 40;
 		p_smbus = pci_get_device(PCI_VENDOR_ID_ATI,
 					 PCI_DEVICE_ID_ATI_SBX00_SMBUS,
 					 NULL);
@@ -2812,9 +2818,11 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci,
 	}
 
 	/* allow 64bit DMA address if supported by H/W */
-	if ((gcap & ICH6_GCAP_64OK) && !pci_set_dma_mask(pci, DMA_BIT_MASK(64)))
-		pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(64));
-	else {
+	if (!(gcap & ICH6_GCAP_64OK))
+		dma_bits = 32;
+	if (!pci_set_dma_mask(pci, DMA_BIT_MASK(dma_bits))) {
+		pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(dma_bits));
+	} else {
 		pci_set_dma_mask(pci, DMA_BIT_MASK(32));
 		pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(32));
 	}
-- 
1.9.1

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