From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752428Ab3AUJqJ (ORCPT ); Mon, 21 Jan 2013 04:46:09 -0500 Received: from mga11.intel.com ([192.55.52.93]:23486 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509Ab3AUJqG convert rfc822-to-8bit (ORCPT ); Mon, 21 Jan 2013 04:46:06 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,505,1355126400"; d="scan'208";a="279690593" Message-ID: <1358761551.12502.39.camel@smile> Subject: Re: [PATCH 2/2] dw_dmac: return proper residue value From: Andy Shevchenko To: Vinod Koul Cc: Andy Shevchenko , Viresh Kumar , linux-kernel@vger.kernel.org, spear-devel Date: Mon, 21 Jan 2013 11:45:51 +0200 In-Reply-To: <20130121084924.GA26562@intel.com> References: <1358758844-24711-1-git-send-email-andriy.shevchenko@linux.intel.com> <1358758844-24711-2-git-send-email-andriy.shevchenko@linux.intel.com> <20130121084924.GA26562@intel.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.4.4-1 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2013-01-21 at 00:49 -0800, Vinod Koul wrote: > On Mon, Jan 21, 2013 at 11:00:44AM +0200, Andy Shevchenko wrote: > > Currently the driver returns full length of the active descriptor which is > > wrong. We have to go throught the active descriptor and sum up the length of > > unsent children in the chain along with the actual data in the DMA channel > why do you mean by children here? The list nodes chained under (active) &desc->tx_list. > > registers. > > > > The cyclic case is not handled by this patch due to len field in the descriptor > > structure is left untouched by the original code. > > > > Signed-off-by: Andy Shevchenko > > --- > > drivers/dma/dw_dmac.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 92 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c > > index d1b9ba2..4325c68 100644 > > --- a/drivers/dma/dw_dmac.c > > +++ b/drivers/dma/dw_dmac.c > > @@ -941,6 +941,97 @@ err_desc_get: > > return NULL; > > } > > > > +/* --------------------- Calculate residue ---------------------------- */ > > + > > +static inline size_t dwc_get_rest(struct dw_dma_chan *dwc, struct dw_desc *desc) > > +{ > > + enum dma_transfer_direction direction = dwc->direction; > > + > > + if (direction == DMA_MEM_TO_DEV || direction == DMA_MEM_TO_MEM) > > + return desc->len - (channel_readl(dwc, SAR) - desc->lli.sar); > > + else if (direction == DMA_DEV_TO_MEM) > > + return desc->len - (channel_readl(dwc, DAR) - desc->lli.dar); > > + > > + return 0; > hmmm, why not use BLOCK_TS value. That way you dont need to look at direction > and along with burst can easily calculate residue... Do you mean to read CTL hi/lo and do desc->len - ctlhi.block_ts * ctllo.src_tr_width? I think it could be not precise when memory-to-peripheral transfer is going on. In that case you probably will have src_tr_width like 32 bits, meanwhile peripheral may receive only byte stream. -- Andy Shevchenko Intel Finland Oy