Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757405Ab3H2XJX (ORCPT ); Thu, 29 Aug 2013 19:09:23 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:58575 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752904Ab3H2XGf (ORCPT ); Thu, 29 Aug 2013 19:06:35 -0400 From: Joel Fernandes To: Sekhar Nori , Matt Porter , Vinod Koul , Dan Williams , Russell King , Sricharan R CC: Linux OMAP List , Linux ARM Kernel List , Linux DaVinci Kernel List , Linux Kernel Mailing List , Linux MMC List , Koen Kooi , Franklin Cooper , Joel Fernandes Subject: [PATCH v4 2/6] dma: edma: Write out and handle MAX_NR_SG at a given time Date: Thu, 29 Aug 2013 18:05:41 -0500 Message-ID: <1377817545-18015-3-git-send-email-joelf@ti.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1377817545-18015-1-git-send-email-joelf@ti.com> References: <1377817545-18015-1-git-send-email-joelf@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4800 Lines: 157 Process SG-elements in batches of MAX_NR_SG if they are greater than MAX_NR_SG. Due to this, at any given time only those many slots will be used in the given channel no matter how long the scatter list is. We keep track of how much has been written inorder to process the next batch of elements in the scatter-list and detect completion. For such intermediate transfer completions (one batch of MAX_NR_SG), make use of pause and resume functions instead of start and stop when such intermediate transfer is in progress or completed as we donot want to clear any pending events. Signed-off-by: Joel Fernandes --- drivers/dma/edma.c | 79 ++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 53 insertions(+), 26 deletions(-) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index e522ad5..732829b 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -56,6 +56,7 @@ struct edma_desc { struct list_head node; int absync; int pset_nr; + int processed; struct edmacc_param pset[0]; }; @@ -104,22 +105,34 @@ static void edma_desc_free(struct virt_dma_desc *vdesc) /* Dispatch a queued descriptor to the controller (caller holds lock) */ static void edma_execute(struct edma_chan *echan) { - struct virt_dma_desc *vdesc = vchan_next_desc(&echan->vchan); + struct virt_dma_desc *vdesc; struct edma_desc *edesc; - int i; - - if (!vdesc) { - echan->edesc = NULL; - return; + struct device *dev = echan->vchan.chan.device->dev; + int i, j, left, nslots; + + /* If either we processed all psets or we're still not started */ + if (!echan->edesc || + echan->edesc->pset_nr == echan->edesc->processed) { + /* Get next vdesc */ + vdesc = vchan_next_desc(&echan->vchan); + if (!vdesc) { + echan->edesc = NULL; + return; + } + list_del(&vdesc->node); + echan->edesc = to_edma_desc(&vdesc->tx); } - list_del(&vdesc->node); + edesc = echan->edesc; - echan->edesc = edesc = to_edma_desc(&vdesc->tx); + /* Find out how many left */ + left = edesc->pset_nr - edesc->processed; + nslots = min(MAX_NR_SG, left); /* Write descriptor PaRAM set(s) */ - for (i = 0; i < edesc->pset_nr; i++) { - edma_write_slot(echan->slot[i], &edesc->pset[i]); + for (i = 0; i < nslots; i++) { + j = i + edesc->processed; + edma_write_slot(echan->slot[i], &edesc->pset[j]); dev_dbg(echan->vchan.chan.device->dev, "\n pset[%d]:\n" " chnum\t%d\n" @@ -132,24 +145,31 @@ static void edma_execute(struct edma_chan *echan) " bidx\t%08x\n" " cidx\t%08x\n" " lkrld\t%08x\n", - i, echan->ch_num, echan->slot[i], - edesc->pset[i].opt, - edesc->pset[i].src, - edesc->pset[i].dst, - edesc->pset[i].a_b_cnt, - edesc->pset[i].ccnt, - edesc->pset[i].src_dst_bidx, - edesc->pset[i].src_dst_cidx, - edesc->pset[i].link_bcntrld); + j, echan->ch_num, echan->slot[i], + edesc->pset[j].opt, + edesc->pset[j].src, + edesc->pset[j].dst, + edesc->pset[j].a_b_cnt, + edesc->pset[j].ccnt, + edesc->pset[j].src_dst_bidx, + edesc->pset[j].src_dst_cidx, + edesc->pset[j].link_bcntrld); /* Link to the previous slot if not the last set */ - if (i != (edesc->pset_nr - 1)) + if (i != (nslots - 1)) edma_link(echan->slot[i], echan->slot[i+1]); /* Final pset links to the dummy pset */ else edma_link(echan->slot[i], echan->ecc->dummy_slot); } - edma_start(echan->ch_num); + edesc->processed += nslots; + + edma_resume(echan->ch_num); + + if (edesc->processed <= MAX_NR_SG) { + dev_dbg(dev, "first transfer starting %d\n", echan->ch_num); + edma_start(echan->ch_num); + } } static int edma_terminate_all(struct edma_chan *echan) @@ -368,19 +388,26 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data) struct edma_desc *edesc; unsigned long flags; - /* Stop the channel */ - edma_stop(echan->ch_num); + /* Pause the channel */ + edma_pause(echan->ch_num); switch (ch_status) { case DMA_COMPLETE: - dev_dbg(dev, "transfer complete on channel %d\n", ch_num); - spin_lock_irqsave(&echan->vchan.lock, flags); edesc = echan->edesc; if (edesc) { + if (edesc->processed == edesc->pset_nr) { + dev_dbg(dev, "transfer complete." \ + " stopping channel %d\n", ch_num); + edma_stop(echan->ch_num); + vchan_cookie_complete(&edesc->vdesc); + } else { + dev_dbg(dev, "Intermediate transfer complete" \ + " on channel %d\n", ch_num); + } + edma_execute(echan); - vchan_cookie_complete(&edesc->vdesc); } spin_unlock_irqrestore(&echan->vchan.lock, flags); -- 1.8.1.2 -- 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/