ALSA: hda/ext: preserve PPLCCTL bits when clearing reset

[PATCH] ALSA: hda/ext: preserve PPLCCTL bits when clearing reset

Posted by raoxu 1 month, 2 weeks ago

From: Xu Rao <raoxu@uniontech.com>

snd_hdac_ext_stream_reset() polls PPLCCTL for STRST by masking the
register value with AZX_PPLCCTL_STRST:

	val = readl(...) & AZX_PPLCCTL_STRST;

The same masked value is then used when clearing STRST. Since val
contains no bits other than STRST, clearing STRST from it always
produces zero. The subsequent writel() therefore writes zero to the
entire PPLCCTL register instead of clearing only the reset bit.

PPLCCTL contains other stream control fields, including the stream tag
in AZX_PPLCCTL_STRM_MASK. Those fields must not be modified as a side
effect of clearing stream reset.

Use snd_hdac_updatel() to clear STRST, matching the existing set-reset
path and preserving all unrelated PPLCCTL bits.

Fixes: df203a4e46f4 ("ALSA: hdac_ext: add extended stream capabilities")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
---
 sound/hda/core/ext/stream.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/hda/core/ext/stream.c b/sound/hda/core/ext/stream.c
index 4c7506d49f55..517bd151fcc3 100644
--- a/sound/hda/core/ext/stream.c
+++ b/sound/hda/core/ext/stream.c
@@ -210,8 +210,8 @@ void snd_hdac_ext_stream_reset(struct hdac_ext_stream *hext_stream)
 			break;
 		udelay(3);
 	} while (--timeout);
-	val &= ~AZX_PPLCCTL_STRST;
-	writel(val, hext_stream->pplc_addr + AZX_REG_PPLCCTL);
+	snd_hdac_updatel(hext_stream->pplc_addr, AZX_REG_PPLCCTL,
+			 AZX_PPLCCTL_STRST, 0);
 	udelay(3);

 	timeout = 50;
--
2.50.1

Re: [PATCH] ALSA: hda/ext: preserve PPLCCTL bits when clearing reset

Posted by Takashi Iwai 1 month, 2 weeks ago

On Thu, 13 Aug 2026 08:55:24 +0200,
raoxu wrote:
> 
> From: Xu Rao <raoxu@uniontech.com>
> 
> snd_hdac_ext_stream_reset() polls PPLCCTL for STRST by masking the
> register value with AZX_PPLCCTL_STRST:
> 
> 	val = readl(...) & AZX_PPLCCTL_STRST;
> 
> The same masked value is then used when clearing STRST. Since val
> contains no bits other than STRST, clearing STRST from it always
> produces zero. The subsequent writel() therefore writes zero to the
> entire PPLCCTL register instead of clearing only the reset bit.
> 
> PPLCCTL contains other stream control fields, including the stream tag
> in AZX_PPLCCTL_STRM_MASK. Those fields must not be modified as a side
> effect of clearing stream reset.
> 
> Use snd_hdac_updatel() to clear STRST, matching the existing set-reset
> path and preserving all unrelated PPLCCTL bits.
> 
> Fixes: df203a4e46f4 ("ALSA: hdac_ext: add extended stream capabilities")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xu Rao <raoxu@uniontech.com>

Applied to for-next branch.  Thanks.


Takashi