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Message-ID: <4F0192F2.3010506@st.com>
Date: Mon, 2 Jan 2012 16:50:18 +0530
From: Pratyush Anand <pratyush.anand@...com>
To: Vinod Koul <vinod.koul@...el.com>
Cc: "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
Vipul Kumar SAMAR <vipulkumar.samar@...com>,
Bhavna YADAV <bhavna.yadav@...com>,
Bhupesh SHARMA <bhupesh.sharma@...com>,
Armando VISCONTI <armando.visconti@...com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Vipin KUMAR <vipin.kumar@...com>,
Shiraz HASHIM <shiraz.hashim@...com>,
Amit VIRDI <Amit.VIRDI@...com>,
Mirko GARDI <mirko.gardi@...com>,
Deepak SIKRI <deepak.sikri@...com>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
Rajeev KUMAR <rajeev-dlh.kumar@...com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Vincenzo FRASCINO <Vincenzo.FRASCINO@...com>,
Viresh KUMAR <viresh.kumar@...com>
Subject: Re: [PATCH] dmaengine/dw_dmac: Add support for device_prep_dma_sg
On 12/23/2011 9:28 PM, Vinod Koul wrote:
> On Tue, 2011-12-13 at 14:17 +0530, Pratyush Anand wrote:
>> Memory to memory copy with scatter gather option has been implemented in
>> this patch. Driver can manage even if number of nodes in src and dst
>> list is different.
> The logic looks okay, but it would be great if we could split this
> prepare here.
> Possibly later when we have multiple such cases we can create templates
> for parsing the non linear sg list and create linear lists from it.
>
Ok. So you suggest to have one patch with a function to align sglist
w.r.t length, and to implement this dwc_prep_dma_sg with aligned list only.
Caller of dwc_prep_dma_sg function will also call something like
align_sg_list(unaligned_dsgl, unaligned ssgl, aligned dsgl,aligned ssgl);
dwc_prep_dma_sg(chan, aligned dsgl, dnents, aligned ssgl, snents, flag);
Is that what you suggest? will do that.
It would be helpful if we can also conclude following discussion.
https://lkml.org/lkml/2011/12/20/95
I am waiting for your reply.
>>
>> Signed-off-by: Pratyush Anand<pratyush.anand@...com>
>> ---
>> drivers/dma/dw_dmac.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 135 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
>> index 96b2750..c1c78c1 100644
>> --- a/drivers/dma/dw_dmac.c
>> +++ b/drivers/dma/dw_dmac.c
>> @@ -729,6 +729,140 @@ err_desc_get:
>> }
>>
>> static struct dma_async_tx_descriptor *
>> +dwc_prep_dma_sg(struct dma_chan *chan,
>> + struct scatterlist *dsgl, unsigned int dst_nents,
>> + struct scatterlist *ssgl, unsigned int src_nents,
>> + unsigned long flags)
>> +{
>> + struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
>> + struct dw_desc *desc;
>> + struct dw_desc *first;
>> + struct dw_desc *prev;
>> + size_t xfer_count;
>> + size_t offset;
>> + unsigned int src_width;
>> + unsigned int dst_width;
>> + u32 ctllo;
>> + struct scatterlist *dsg, *ssg;
>> + dma_addr_t src = 0, dst = 0;
>> + unsigned int slen = 0, dlen = 0, total_len = 0;
>> + unsigned int i, nents, len = 0, incs, si = 0, di = 0;
>> +
>> + if (unlikely(!src_nents))
>> + return NULL;
>> +
>> + if (unlikely(!dst_nents))
>> + return NULL;
>> +
>> + prev = first = NULL;
>> +
>> + dsg = dsgl;
>> + ssg = ssgl;
>> + nents = max(src_nents, dst_nents);
> shouldn't you validate if total src sg length and dstn sg lengths are
> same here?
Yes, will modify.
Probably we will not need it having aligned sglists.
>> +
>> + if (nents == src_nents)
>> + incs = true;
>> + else
>> + incs = false;
>> +
>> + for (i = 0; i< nents;) {
>> + if (!slen) {
>> + src = sg_dma_address(ssg);
>> + slen = sg_dma_len(ssg);
>> + ssg = sg_next(ssg);
>> + if (!ssg&& si< src_nents - 1)
>> + goto err_sg_len;
>> + si++;
>> + } else
>> + src += len;
>> +
>> + if (!dlen) {
>> + dst = sg_dma_address(dsg);
>> + dlen = sg_dma_len(dsg);
>> + dsg = sg_next(dsg);
>> + if (!dsg&& di< dst_nents - 1)
>> + goto err_sg_len;
> this could be made better lokking by using helpers
ok. having aligned sglists, logic will be lot simpler.
>
>> + di++;
>> + } else
>> + dst += len;
>> +
>> + if (incs)
>> + i = si;
>> + else
>> + i = di;
>> + len = min(slen, dlen);
>> + slen -= len;
>> + dlen -= len;
>> +
>> + if (!((src | dst | len)& 7))
>> + src_width = dst_width = 3;
>> + else if (!((src | dst | len)& 3))
>> + src_width = dst_width = 2;
>> + else if (!((src | dst | len)& 1))
>> + src_width = dst_width = 1;
>> + else
>> + src_width = dst_width = 0;
> how about putting this is get_me_the_length()
Yes, can do that. Similar logic has been used in other function in this
file. So may be I need to modify those functions too in a separate patch.
>> +
>> + ctllo = DWC_DEFAULT_CTLLO(chan->private)
>> + | DWC_CTLL_DST_WIDTH(dst_width)
>> + | DWC_CTLL_SRC_WIDTH(src_width)
>> + | DWC_CTLL_DST_INC
>> + | DWC_CTLL_SRC_INC
>> + | DWC_CTLL_FC_M2M;
>> +
>> + offset = 0;
>> + while ((len - offset)> 0) {
>> +
>> + xfer_count = min_t(size_t, (len - offset)>> dst_width,
>> + DWC_MAX_COUNT);
>> +
>> + desc = dwc_desc_get(dwc);
>> + if (!desc)
>> + goto err_desc_get;
>> +
>> + desc->lli.sar = src + offset;
>> + desc->lli.dar = dst + offset;
>> + desc->lli.ctllo = ctllo;
>> + desc->lli.ctlhi = xfer_count;
>> +
>> + if (!first) {
>> + first = desc;
>> + } else {
>> + prev->lli.llp = desc->txd.phys;
>> + dma_sync_single_for_device(chan2parent(chan),
>> + prev->txd.phys,
>> + sizeof(prev->lli),
>> + DMA_TO_DEVICE);
>> + list_add_tail(&desc->desc_node,
>> + &first->tx_list);
>> + }
>> + prev = desc;
>> + offset += xfer_count<< dst_width;
>> + }
>> + total_len += len;
>> + }
>> +
>> + if (flags& DMA_PREP_INTERRUPT)
>> + /* Trigger interrupt after last block */
>> + prev->lli.ctllo |= DWC_CTLL_INT_EN;
>> +
>> + prev->lli.llp = 0;
>> + dma_sync_single_for_device(chan2parent(chan),
>> + prev->txd.phys, sizeof(prev->lli),
>> + DMA_TO_DEVICE);
>> +
>> + first->txd.flags = flags;
>> + first->len = total_len;
>> +
>> + return&first->txd;
>> +
>> +err_sg_len:
>> +err_desc_get:
>> + dwc_desc_put(dwc, first);
>> + return NULL;
>> +}
>> +
>> +static struct dma_async_tx_descriptor *
>> dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
>> unsigned int sg_len, enum dma_transfer_direction direction,
>> unsigned long flags)
>> @@ -1471,6 +1605,7 @@ static int __init dw_probe(struct platform_device *pdev)
>> dw->dma.device_free_chan_resources = dwc_free_chan_resources;
>>
>> dw->dma.device_prep_dma_memcpy = dwc_prep_dma_memcpy;
>> + dw->dma.device_prep_dma_sg = dwc_prep_dma_sg;
>>
>> dw->dma.device_prep_slave_sg = dwc_prep_slave_sg;
>> dw->dma.device_control = dwc_control;
>> --
>> 1.7.2.2
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
>
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