Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758744AbcLOQLO (ORCPT ); Thu, 15 Dec 2016 11:11:14 -0500 Received: from smtprelay2.synopsys.com ([198.182.60.111]:37148 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752560AbcLOQLM (ORCPT ); Thu, 15 Dec 2016 11:11:12 -0500 Subject: Re: [PATCH 2/3] dmaeninge: xilinx_dma: Fix bug in multiple frame stores scenario in vdma To: Kedareswara rao Appana , , , , , , , , , , , References: <1481814682-31780-1-git-send-email-appanad@xilinx.com> <1481814682-31780-3-git-send-email-appanad@xilinx.com> CC: , , From: Jose Abreu Message-ID: <9d92984b-e04a-cd29-e933-d8ea4d610c94@synopsys.com> Date: Thu, 15 Dec 2016 16:10:20 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1481814682-31780-3-git-send-email-appanad@xilinx.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.107.19.59] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3422 Lines: 107 Hi Kedar, On 15-12-2016 15:11, Kedareswara rao Appana wrote: > When VDMA is configured for more than one frame in the h/w > for example h/w is configured for n number of frames and user > Submits n number of frames and triggered the DMA using issue_pending API. > In the current driver flow we are submitting one frame at a time > but we should submit all the n number of frames at one time as the h/w > Is configured for n number of frames. > > This patch fixes this issue. > > Signed-off-by: Kedareswara rao Appana > --- > drivers/dma/xilinx/xilinx_dma.c | 43 +++++++++++++++++++++++++---------------- > 1 file changed, 26 insertions(+), 17 deletions(-) > > diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c > index 736c2a3..4f3fa94 100644 > --- a/drivers/dma/xilinx/xilinx_dma.c > +++ b/drivers/dma/xilinx/xilinx_dma.c > @@ -1087,23 +1087,33 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan) > tail_segment->phys); > } else { > struct xilinx_vdma_tx_segment *segment, *last = NULL; > - int i = 0; > + int i = 0, j = 0; > > if (chan->desc_submitcount < chan->num_frms) > i = chan->desc_submitcount; > > - list_for_each_entry(segment, &desc->segments, node) { > - if (chan->ext_addr) > - vdma_desc_write_64(chan, > - XILINX_VDMA_REG_START_ADDRESS_64(i++), > - segment->hw.buf_addr, > - segment->hw.buf_addr_msb); > - else > - vdma_desc_write(chan, > - XILINX_VDMA_REG_START_ADDRESS(i++), > - segment->hw.buf_addr); > - > - last = segment; > + for (j = 0; j < chan->num_frms; ) { > + list_for_each_entry(segment, &desc->segments, node) { > + if (chan->ext_addr) > + vdma_desc_write_64(chan, > + XILINX_VDMA_REG_START_ADDRESS_64(i++), > + segment->hw.buf_addr, > + segment->hw.buf_addr_msb); > + else > + vdma_desc_write(chan, > + XILINX_VDMA_REG_START_ADDRESS(i++), > + segment->hw.buf_addr); > + > + last = segment; Hmm, is it possible to submit more than one segment? If so, then i and j will get out of sync. > + } > + list_del(&desc->node); > + list_add_tail(&desc->node, &chan->active_list); > + j++; But if i is non zero and pending_list has more than num_frms then i will not wrap-around as it should and will write to invalid framebuffer location, right? > + if (list_empty(&chan->pending_list)) > + break; > + desc = list_first_entry(&chan->pending_list, > + struct xilinx_dma_tx_descriptor, > + node); > } > > if (!last) > @@ -1114,14 +1124,13 @@ static void xilinx_vdma_start_transfer(struct xilinx_dma_chan *chan) > vdma_desc_write(chan, XILINX_DMA_REG_FRMDLY_STRIDE, > last->hw.stride); > vdma_desc_write(chan, XILINX_DMA_REG_VSIZE, last->hw.vsize); Maybe a check that all framebuffers contain valid addresses should be done before programming vsize so that VDMA does not try to write to invalid addresses. > + > + chan->desc_submitcount += j; > + chan->desc_pendingcount -= j; > } > > chan->idle = false; > if (!chan->has_sg) { > - list_del(&desc->node); > - list_add_tail(&desc->node, &chan->active_list); > - chan->desc_submitcount++; > - chan->desc_pendingcount--; > if (chan->desc_submitcount == chan->num_frms) > chan->desc_submitcount = 0; "desc_submitcount >= chan->num_frms would be safer here. > } else { Best regards, Jose Miguel Abreu