lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 15 Jun 2015 23:00:09 +0900
From:	Krzysztof Kozlowski <k.kozlowski.k@...il.com>
To:	Dan Williams <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	gabriel@...een.is, Marek Szyprowski <m.szyprowski@...sung.com>,
	Krzysztof Kozlowski <k.kozlowski.k@...il.com>,
	<stable@...r.kernel.org>
Subject: [PATCH] dmaengine: pl330: Really fix choppy sound because of wrong residue calculation

When pl330 driver was used during sound playback, after some time or
after a number of plays the sound became choppy or totally noisy. For
example on Odroid XU3 board the first four executions of aplay with
small WAVE worked fine, but fifth was unrecognizable with errors:
	$ aplay /usr/share/sounds/alsa/Front_Right.wava
	underrun!!! (at least 0.095 ms long)

Issue was caused by wrong residue reported by pl330 driver to
pcm_dmaengine for its cyclic dma transfers.

The pl330_tx_status(), residue reporting function, used a "last" flag in
a descriptor to indicate that there is no more data to send.

The pl330_tx_submit() iterated over descriptors trying to remove this
flag from them and then mark last descriptor as "last".  However when
iterating it actually removed the flag not from descriptors but always
from last of it (and then reset it). Thus effectively once some
descriptor was marked as last, then it stayed like this forever causing
residue to be reported too low.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@...il.com>
Fixes: aee4d1fac887 ("dmaengine: pl330: improve pl330_tx_status() function")
Cc: <stable@...r.kernel.org>
Reported-by: gabriel@...een.is
Suggested-by: Marek Szyprowski <m.szyprowski@...sung.com>

---

This fixes sound on my Odroid XU3. Tests on other boards are welcomed!
---
 drivers/dma/pl330.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index f513f77b1d85..4feb65a6b3b0 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2328,7 +2328,7 @@ static dma_cookie_t pl330_tx_submit(struct dma_async_tx_descriptor *tx)
 			desc->txd.callback = last->txd.callback;
 			desc->txd.callback_param = last->txd.callback_param;
 		}
-		last->last = false;
+		desc->last = false;
 
 		dma_cookie_assign(&desc->txd);
 
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists