> -----Original Message-----
> From: Vinod Koul <vkoul@xxxxxxxxxx>
> Sent: 09 November 2020 5:42 PM
> To: Sia, Jee Heng <jee.heng.sia@xxxxxxxxx>
> Cc: Eugeniy.Paltsev@xxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 07/15] dmaegine: dw-axi-dmac: Support
> device_prep_dma_cyclic()
>
> On 27-10-20, 14:38, Sia Jee Heng wrote:
> > Add support for device_prep_dma_cyclic() callback function to benefit
> > DMA cyclic client, for example ALSA.
> >
> > Existing AxiDMA driver only support data transfer between memory to
> memory.
> > Data transfer between device to memory and memory to device in cyclic
> > mode would failed if this interface is not supported by the AxiDMA driver.
> >
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Signed-off-by: Sia Jee Heng <jee.heng.sia@xxxxxxxxx>
> > ---
> > .../dma/dw-axi-dmac/dw-axi-dmac-platform.c | 182 +++++++++++++++++-
> > drivers/dma/dw-axi-dmac/dw-axi-dmac.h | 2 +
> > 2 files changed, 177 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > index 1124c97025f2..9e574753aaf0 100644
> > --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > @@ -15,6 +15,8 @@
> > #include <linux/err.h>
> > #include <linux/interrupt.h>
> > #include <linux/io.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/io-64-nonatomic-lo-hi.h>
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > #include <linux/of.h>
> > @@ -575,6 +577,135 @@ dma_chan_prep_dma_memcpy(struct dma_chan
> *dchan, dma_addr_t dst_adr,
> > return NULL;
> > }
> >
> > +static struct dma_async_tx_descriptor *
> > +dw_axi_dma_chan_prep_cyclic(struct dma_chan *dchan, dma_addr_t
> dma_addr,
> > + size_t buf_len, size_t period_len,
> > + enum dma_transfer_direction direction,
> > + unsigned long flags)
> > +{
> > + struct axi_dma_chan *chan = dchan_to_axi_dma_chan(dchan);
> > + u32 data_width = BIT(chan->chip->dw->hdata->m_data_width);
> > + struct axi_dma_hw_desc *hw_desc = NULL;
> > + struct axi_dma_desc *desc = NULL;
> > + dma_addr_t src_addr = dma_addr;
> > + u32 num_periods = buf_len / period_len;
> > + unsigned int reg_width;
> > + unsigned int mem_width;
> > + dma_addr_t reg;
> > + unsigned int i;
> > + u32 ctllo, ctlhi;
> > + size_t block_ts;
> > + u64 llp = 0;
> > + u8 lms = 0; /* Select AXI0 master for LLI fetching */
> > +
> > + block_ts = chan->chip->dw->hdata->block_size[chan->id];
> > +
> > + mem_width = __ffs(data_width | dma_addr | period_len);
> > + if (mem_width > DWAXIDMAC_TRANS_WIDTH_32)
> > + mem_width = DWAXIDMAC_TRANS_WIDTH_32;
> > +
> > + desc = axi_desc_alloc(num_periods);
> > + if (unlikely(!desc))
> > + goto err_desc_get;
> > +
> > + chan->direction = direction;
> > + desc->chan = chan;
> > + chan->cyclic = true;
> > +
> > + switch (direction) {
> > + case DMA_MEM_TO_DEV:
> > + reg_width = __ffs(chan->config.dst_addr_width);
> > + reg = chan->config.dst_addr;
> > + ctllo = reg_width << CH_CTL_L_DST_WIDTH_POS |
> > + DWAXIDMAC_CH_CTL_L_NOINC <<
> CH_CTL_L_DST_INC_POS |
> > + DWAXIDMAC_CH_CTL_L_INC <<
> CH_CTL_L_SRC_INC_POS;
> > + break;
> > + case DMA_DEV_TO_MEM:
> > + reg_width = __ffs(chan->config.src_addr_width);
> > + reg = chan->config.src_addr;
> > + ctllo = reg_width << CH_CTL_L_SRC_WIDTH_POS |
> > + DWAXIDMAC_CH_CTL_L_INC <<
> CH_CTL_L_DST_INC_POS |
> > + DWAXIDMAC_CH_CTL_L_NOINC <<
> CH_CTL_L_SRC_INC_POS;
> > + break;
> > + default:
> > + return NULL;
> > + }
> > +
> > + for (i = 0; i < num_periods; i++) {
> > + hw_desc = &desc->hw_desc[i];
> > +
> > + hw_desc->lli = axi_desc_get(chan, &hw_desc->llp);
> > + if (unlikely(!hw_desc->lli))
> > + goto err_desc_get;
> > +
> > + if (direction == DMA_MEM_TO_DEV)
> > + block_ts = period_len >> mem_width;
> > + else
> > + block_ts = period_len >> reg_width;
> > +
> > + ctlhi = CH_CTL_H_LLI_VALID;
> > + if (chan->chip->dw->hdata->restrict_axi_burst_len) {
> > + u32 burst_len = chan->chip->dw->hdata-
> >axi_rw_burst_len;
> > +
> > + ctlhi |= (CH_CTL_H_ARLEN_EN |
> > + burst_len << CH_CTL_H_ARLEN_POS |
> > + CH_CTL_H_AWLEN_EN |
> > + burst_len << CH_CTL_H_AWLEN_POS);
> > + }
> > +
> > + hw_desc->lli->ctl_hi = cpu_to_le32(ctlhi);
> > +
> > + if (direction == DMA_MEM_TO_DEV)
> > + ctllo |= mem_width << CH_CTL_L_SRC_WIDTH_POS;
> > + else
> > + ctllo |= mem_width << CH_CTL_L_DST_WIDTH_POS;
> > +
> > + if (direction == DMA_MEM_TO_DEV) {
> > + write_desc_sar(hw_desc, src_addr);
> > + write_desc_dar(hw_desc, reg);
> > + } else {
> > + write_desc_sar(hw_desc, reg);
> > + write_desc_dar(hw_desc, src_addr);
> > + }
> > +
> > + hw_desc->lli->block_ts_lo = cpu_to_le32(block_ts - 1);
> > +
> > + ctllo |= (DWAXIDMAC_BURST_TRANS_LEN_4 <<
> CH_CTL_L_DST_MSIZE_POS |
> > + DWAXIDMAC_BURST_TRANS_LEN_4 <<
> CH_CTL_L_SRC_MSIZE_POS);
> > + hw_desc->lli->ctl_lo = cpu_to_le32(ctllo);
> > +
> > + set_desc_src_master(hw_desc);
> > +
> > + /*
> > + * Set end-of-link to the linked descriptor, so that cyclic
> > + * callback function can be triggered during interrupt.
> > + */
> > + set_desc_last(hw_desc);
> > +
> > + src_addr += period_len;
> > + }
>
> apart from this bit and use of periods instead of sg_list this seems very similar to
> slave handler, so can you please move common bits to helpers and
> remove/reduce duplicate code
[>>] sure, will try to reduce the common code.
>
> --
> ~Vinod
