Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754015AbbGPMAN (ORCPT ); Thu, 16 Jul 2015 08:00:13 -0400 Received: from mga14.intel.com ([192.55.52.115]:35526 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752330AbbGPMAK (ORCPT ); Thu, 16 Jul 2015 08:00:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,487,1432623600"; d="scan'208";a="748511434" Date: Thu, 16 Jul 2015 17:31:54 +0530 From: Vinod Koul To: Maxime Ripard Cc: Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , Thomas Petazzoni , Boris Brezillon , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/2] dmaengine: xdmac: Add scatter gathered memset support Message-ID: <20150716120154.GN5086@localhost> References: <1436177964-19380-1-git-send-email-maxime.ripard@free-electrons.com> <1436177964-19380-3-git-send-email-maxime.ripard@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1436177964-19380-3-git-send-email-maxime.ripard@free-electrons.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7335 Lines: 225 On Mon, Jul 06, 2015 at 12:19:24PM +0200, Maxime Ripard wrote: > The XDMAC also supports memset operations over discontiguous areas. Add the > necessary logic to support this. > > Signed-off-by: Maxime Ripard > --- > drivers/dma/at_xdmac.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 165 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c > index cf1213de7865..1a2d9a39ff25 100644 > --- a/drivers/dma/at_xdmac.c > +++ b/drivers/dma/at_xdmac.c > @@ -1133,7 +1133,7 @@ static struct at_xdmac_desc *at_xdmac_memset_create_desc(struct dma_chan *chan, > * SAMA5D4x), so we can use the same interface for source and dest, > * that solves the fact we don't know the direction. > */ > - u32 chan_cc = AT_XDMAC_CC_DAM_INCREMENTED_AM > + u32 chan_cc = AT_XDMAC_CC_DAM_UBS_AM > | AT_XDMAC_CC_SAM_INCREMENTED_AM > | AT_XDMAC_CC_DIF(0) > | AT_XDMAC_CC_SIF(0) > @@ -1201,6 +1201,168 @@ at_xdmac_prep_dma_memset(struct dma_chan *chan, dma_addr_t dest, int value, > return &desc->tx_dma_desc; > } > > +static struct dma_async_tx_descriptor * > +at_xdmac_prep_dma_memset_sg(struct dma_chan *chan, struct scatterlist *sgl, > + unsigned int sg_len, int value, > + unsigned long flags) > +{ > + struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan); > + struct at_xdmac_desc *desc, *pdesc = NULL, > + *ppdesc = NULL, *first = NULL; > + struct scatterlist *sg, *psg = NULL, *ppsg = NULL; > + size_t stride = 0, pstride = 0, len = 0; > + int i; > + > + if (!sgl) > + return NULL; > + > + dev_dbg(chan2dev(chan), "%s: sg_len=%d, value=0x%x, flags=0x%lx\n", > + __func__, sg_len, value, flags); > + > + /* Prepare descriptors. */ > + for_each_sg(sgl, sg, sg_len, i) { > + dev_dbg(chan2dev(chan), "%s: dest=0x%08x, len=%d, pattern=0x%x, flags=0x%lx\n", > + __func__, sg_dma_address(sg), sg_dma_len(sg), > + value, flags); > + desc = at_xdmac_memset_create_desc(chan, atchan, > + sg_dma_address(sg), > + sg_dma_len(sg), > + value); > + if (!desc && first) > + list_splice_init(&first->descs_list, > + &atchan->free_descs_list); > + > + if (!first) > + first = desc; > + > + /* Update our strides */ > + pstride = stride; > + if (psg) > + stride = sg_dma_address(sg) - > + (sg_dma_address(psg) + sg_dma_len(psg)); > + > + /* > + * The scatterlist API gives us only the address and > + * length of each elements. > + * > + * Unfortunately, we don't have the stride, which we > + * will need to compute. > + * > + * That make us end up in a situation like this one: > + * len stride len stride len > + * +-------+ +-------+ +-------+ > + * | N-2 | | N-1 | | N | > + * +-------+ +-------+ +-------+ > + * > + * We need all these three elements (N-2, N-1 and N) > + * to actually take the decision on whether we need to > + * queue N-1 or reuse N-2. > + * > + * We will only consider N if it is the last element. > + */ Why do you need stride? This is scatterlist so the computation of stride sounds odd here. Ideally you should take the scatterlist and program the lli for controller. -- ~Vinod > + if (ppdesc && pdesc) { > + if ((stride == pstride) && > + (sg_dma_len(ppsg) == sg_dma_len(psg))) { > + dev_dbg(chan2dev(chan), > + "%s: desc 0x%p can be merged with desc 0x%p\n", > + __func__, pdesc, ppdesc); > + > + /* > + * Increment the block count of the > + * N-2 descriptor > + */ > + at_xdmac_increment_block_count(chan, ppdesc); > + ppdesc->lld.mbr_dus = stride; > + > + /* > + * Put back the N-1 descriptor in the > + * free descriptor list > + */ > + list_add_tail(&pdesc->desc_node, > + &atchan->free_descs_list); > + > + /* > + * Make our N-1 descriptor pointer > + * point to the N-2 since they were > + * actually merged. > + */ > + pdesc = ppdesc; > + > + /* > + * Rule out the case where we don't have > + * pstride computed yet (our second sg > + * element) > + * > + * We also want to catch the case where there > + * would be a negative stride, > + */ > + } else if (pstride || > + sg_dma_address(sg) < sg_dma_address(psg)) { > + /* > + * Queue the N-1 descriptor after the > + * N-2 > + */ > + at_xdmac_queue_desc(chan, ppdesc, pdesc); > + > + /* > + * Add the N-1 descriptor to the list > + * of the descriptors used for this > + * transfer > + */ > + list_add_tail(&desc->desc_node, > + &first->descs_list); > + dev_dbg(chan2dev(chan), > + "%s: add desc 0x%p to descs_list 0x%p\n", > + __func__, desc, first); > + } > + } > + > + /* > + * If we are the last element, just see if we have the > + * same size than the previous element. > + * > + * If so, we can merge it with the previous descriptor > + * since we don't care about the stride anymore. > + */ > + if ((i == (sg_len - 1)) && > + sg_dma_len(ppsg) == sg_dma_len(psg)) { > + dev_dbg(chan2dev(chan), > + "%s: desc 0x%p can be merged with desc 0x%p\n", > + __func__, desc, pdesc); > + > + /* > + * Increment the block count of the N-1 > + * descriptor > + */ > + at_xdmac_increment_block_count(chan, pdesc); > + pdesc->lld.mbr_dus = stride; > + > + /* > + * Put back the N descriptor in the free > + * descriptor list > + */ > + list_add_tail(&desc->desc_node, > + &atchan->free_descs_list); > + } > + > + /* Update our descriptors */ > + ppdesc = pdesc; > + pdesc = desc; > + > + /* Update our scatter pointers */ > + ppsg = psg; > + psg = sg; > + > + len += sg_dma_len(sg); > + } > + > + first->tx_dma_desc.cookie = -EBUSY; > + first->tx_dma_desc.flags = flags; > + first->xfer_size = len; > + > + return &first->tx_dma_desc; > +} > + > static enum dma_status > at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie, > struct dma_tx_state *txstate) > @@ -1734,6 +1896,7 @@ static int at_xdmac_probe(struct platform_device *pdev) > dma_cap_set(DMA_INTERLEAVE, atxdmac->dma.cap_mask); > dma_cap_set(DMA_MEMCPY, atxdmac->dma.cap_mask); > dma_cap_set(DMA_MEMSET, atxdmac->dma.cap_mask); > + dma_cap_set(DMA_MEMSET_SG, atxdmac->dma.cap_mask); > dma_cap_set(DMA_SLAVE, atxdmac->dma.cap_mask); > /* > * Without DMA_PRIVATE the driver is not able to allocate more than > @@ -1749,6 +1912,7 @@ static int at_xdmac_probe(struct platform_device *pdev) > atxdmac->dma.device_prep_interleaved_dma = at_xdmac_prep_interleaved; > atxdmac->dma.device_prep_dma_memcpy = at_xdmac_prep_dma_memcpy; > atxdmac->dma.device_prep_dma_memset = at_xdmac_prep_dma_memset; > + atxdmac->dma.device_prep_dma_memset_sg = at_xdmac_prep_dma_memset_sg; > atxdmac->dma.device_prep_slave_sg = at_xdmac_prep_slave_sg; > atxdmac->dma.device_config = at_xdmac_device_config; > atxdmac->dma.device_pause = at_xdmac_device_pause; > -- > 2.4.5 > -- -- 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/