ALSA: hda: Conditionally use snooping for AMD HDMI

The recent regression report revealed that the use of WC pages for AMD
HDMI device together with AMD IOMMU leads to unexpected truncation or
noises.  The issue seems triggered by the change in the kernel core
memory allocation that enables IOMMU driver to use always S/G
buffers.  Meanwhile, the use of WC pages has been a workaround for the
similar issue with standard pages in the past.  So, now we need to
apply the workaround conditionally, namely, only when IOMMU isn't in
place.

This patch modifies the workaround code to check the DMA ops at first
and apply the snoop-off only when needed.

Fixes: f5ff79fddf0e ("dma-mapping: remove CONFIG_DMA_REMAP")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219087
Link: https://patch.msgid.link/20240731170521.31714-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/hda_controller.h b/sound/pci/hda/hda_controller.h
index c2d0109866e62e5a93f915ad202ce71c0f84d6b9..68c883f202ca5bac763b0b07a81084067df4ec60 100644 (file)
--- a/sound/pci/hda/hda_controller.h
+++ b/sound/pci/hda/hda_controller.h
@@ -28,7 +28,7 @@
 #else
 #define AZX_DCAPS_I915_COMPONENT 0             /* NOP */
 #endif
-/* 14 unused */
+#define AZX_DCAPS_AMD_ALLOC_FIX        (1 << 14)       /* AMD allocation workaround */
 #define AZX_DCAPS_CTX_WORKAROUND (1 << 15)     /* X-Fi workaround */
 #define AZX_DCAPS_POSFIX_LPIB  (1 << 16)       /* Use LPIB as default */
 #define AZX_DCAPS_AMD_WORKAROUND (1 << 17)     /* AMD-specific workaround */

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index b33602e64d174c8af1bf196ee5b0ce90668f9681..97d33a48ff17c80628cef26f1e690fdcf57dd0d8 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -40,6 +40,7 @@
 
 #ifdef CONFIG_X86
 /* for snoop control */
+#include <linux/dma-map-ops.h>
 #include <asm/set_memory.h>
 #include <asm/cpufeature.h>
 #endif
@@ -306,7 +307,7 @@ enum {
 
 /* quirks for ATI HDMI with snoop off */
 #define AZX_DCAPS_PRESET_ATI_HDMI_NS \
-       (AZX_DCAPS_PRESET_ATI_HDMI | AZX_DCAPS_SNOOP_OFF)
+       (AZX_DCAPS_PRESET_ATI_HDMI | AZX_DCAPS_AMD_ALLOC_FIX)
 
 /* quirks for AMD SB */
 #define AZX_DCAPS_PRESET_AMD_SB \
@@ -1702,6 +1703,13 @@ static void azx_check_snoop_available(struct azx *chip)
        if (chip->driver_caps & AZX_DCAPS_SNOOP_OFF)
                snoop = false;
 
+#ifdef CONFIG_X86
+       /* check the presence of DMA ops (i.e. IOMMU), disable snoop conditionally */
+       if ((chip->driver_caps & AZX_DCAPS_AMD_ALLOC_FIX) &&
+           !get_dma_ops(chip->card->dev))
+               snoop = false;
+#endif
+
        chip->snoop = snoop;
        if (!snoop) {
                dev_info(chip->card->dev, "Force to non-snoop mode\n");