Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755499AbbFOOCs (ORCPT ); Mon, 15 Jun 2015 10:02:48 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:35366 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755323AbbFOOCp (ORCPT ); Mon, 15 Jun 2015 10:02:45 -0400 From: Krzysztof Kozlowski To: Dan Williams , Vinod Koul , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Cc: gabriel@unseen.is, Marek Szyprowski , Krzysztof Kozlowski , Subject: [PATCH] dmaengine: pl330: Really fix choppy sound because of wrong residue calculation Date: Mon, 15 Jun 2015 23:00:09 +0900 Message-Id: <1434376809-8029-1-git-send-email-k.kozlowski.k@gmail.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2084 Lines: 54 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 Fixes: aee4d1fac887 ("dmaengine: pl330: improve pl330_tx_status() function") Cc: Reported-by: gabriel@unseen.is Suggested-by: Marek Szyprowski --- 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/