On Thu, May 12, 2022 at 8:52 AM Kishon Vijay Abraham I <kishon@xxxxxx> wrote:
>
> Hi Frank,
>
> On 03/05/22 06:28, Frank Li wrote:
> > Some Endpoints controllers have DMA capabilities. This DMA controller has
> > more efficiency then a general external DMA controller. And this DMA
> > controller can bypass outbound memory address translation unit.
> >
> > The whole flow use standard DMA usage module
> >
> > 1. Using dma_request_channel() and filter function to find correct
> > RX and TX Channel. if not exist, fallback to try allocate
> > general DMA controller channel.
> > 2. dmaengine_slave_config() config remote side physcial address.
> > 3. using dmaengine_prep_slave_single() create transfer descriptor.
> > 4. tx_submit();
> > 5. dma_async_issue_pending();
> >
> > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>
> The patch looks good to me (other than Lorenzo's comment on the
> description). Did you also verify DMA_MEMCPY just to make sure, the old
> path continues to work?
Not yet, our hardware platform has not memory to memory DMA.
best regards
Frank Li
>
> Regards,
> Kishon
> > ---
> > Change from v9 to v10:
> > - rewrite commit message
> > Change from v4 to v9:
> > - none
> > Change from v3 to v4:
> > - reverse Xmas tree order
> > - local -> dma_local
> > - change error message
> > - IS_ERR -> IS_ERR_OR_NULL
> > - check return value of dmaengine_slave_config()
> > Change from v1 to v2:
> > - none
> >
> > drivers/pci/endpoint/functions/pci-epf-test.c | 108 ++++++++++++++++--
> > 1 file changed, 98 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index 90d84d3bc868f..f26afd02f3a86 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -52,9 +52,11 @@ struct pci_epf_test {
> > enum pci_barno test_reg_bar;
> > size_t msix_table_offset;
> > struct delayed_work cmd_handler;
> > - struct dma_chan *dma_chan;
> > + struct dma_chan *dma_chan_tx;
> > + struct dma_chan *dma_chan_rx;
> > struct completion transfer_complete;
> > bool dma_supported;
> > + bool dma_private;
> > const struct pci_epc_features *epc_features;
> > };
> >
> > @@ -105,12 +107,15 @@ static void pci_epf_test_dma_callback(void *param)
> > */
> > static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> > dma_addr_t dma_dst, dma_addr_t dma_src,
> > - size_t len)
> > + size_t len, dma_addr_t dma_remote,
> > + enum dma_transfer_direction dir)
> > {
> > + struct dma_chan *chan = (dir == DMA_DEV_TO_MEM) ? epf_test->dma_chan_tx : epf_test->dma_chan_rx;
> > + dma_addr_t dma_local = (dir == DMA_MEM_TO_DEV) ? dma_src : dma_dst;
> > enum dma_ctrl_flags flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> > - struct dma_chan *chan = epf_test->dma_chan;
> > struct pci_epf *epf = epf_test->epf;
> > struct dma_async_tx_descriptor *tx;
> > + struct dma_slave_config sconf = {};
> > struct device *dev = &epf->dev;
> > dma_cookie_t cookie;
> > int ret;
> > @@ -120,7 +125,22 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> > return -EINVAL;
> > }
> >
> > - tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
> > + if (epf_test->dma_private) {
> > + sconf.direction = dir;
> > + if (dir == DMA_MEM_TO_DEV)
> > + sconf.dst_addr = dma_remote;
> > + else
> > + sconf.src_addr = dma_remote;
> > +
> > + if (dmaengine_slave_config(chan, &sconf)) {
> > + dev_err(dev, "DMA slave config fail\n");
> > + return -EIO;
> > + }
> > + tx = dmaengine_prep_slave_single(chan, dma_local, len, dir, flags);
> > + } else {
> > + tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
> > + }
> > +
> > if (!tx) {
> > dev_err(dev, "Failed to prepare DMA memcpy\n");
> > return -EIO;
> > @@ -148,6 +168,23 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> > return 0;
> > }
> >
> > +struct epf_dma_filter {
> > + struct device *dev;
> > + u32 dma_mask;
> > +};
> > +
> > +static bool epf_dma_filter_fn(struct dma_chan *chan, void *node)
> > +{
> > + struct epf_dma_filter *filter = node;
> > + struct dma_slave_caps caps;
> > +
> > + memset(&caps, 0, sizeof(caps));
> > + dma_get_slave_caps(chan, &caps);
> > +
> > + return chan->device->dev == filter->dev
> > + && (filter->dma_mask & caps.directions);
> > +}
> > +
> > /**
> > * pci_epf_test_init_dma_chan() - Function to initialize EPF test DMA channel
> > * @epf_test: the EPF test device that performs data transfer operation
> > @@ -158,10 +195,44 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
> > {
> > struct pci_epf *epf = epf_test->epf;
> > struct device *dev = &epf->dev;
> > + struct epf_dma_filter filter;
> > struct dma_chan *dma_chan;
> > dma_cap_mask_t mask;
> > int ret;
> >
> > + filter.dev = epf->epc->dev.parent;
> > + filter.dma_mask = BIT(DMA_DEV_TO_MEM);
> > +
> > + dma_cap_zero(mask);
> > + dma_cap_set(DMA_SLAVE, mask);
> > + dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
> > + if (IS_ERR_OR_NULL(dma_chan)) {
> > + dev_info(dev, "Failed to get private DMA channel. Falling back to generic one\n");
> > + goto fail_back_tx;
> > + }
> > +
> > + epf_test->dma_chan_rx = dma_chan;
> > +
> > + filter.dma_mask = BIT(DMA_MEM_TO_DEV);
> > + dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
> > +
> > + if (IS_ERR(dma_chan)) {
> > + dev_info(dev, "Failed to get private DMA channel. Falling back to generic one\n");
> > + goto fail_back_rx;
> > + }
> > +
> > + epf_test->dma_chan_tx = dma_chan;
> > + epf_test->dma_private = true;
> > +
> > + init_completion(&epf_test->transfer_complete);
> > +
> > + return 0;
> > +
> > +fail_back_rx:
> > + dma_release_channel(epf_test->dma_chan_rx);
> > + epf_test->dma_chan_tx = NULL;
> > +
> > +fail_back_tx:
> > dma_cap_zero(mask);
> > dma_cap_set(DMA_MEMCPY, mask);
> >
> > @@ -174,7 +245,7 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
> > }
> > init_completion(&epf_test->transfer_complete);
> >
> > - epf_test->dma_chan = dma_chan;
> > + epf_test->dma_chan_tx = epf_test->dma_chan_rx = dma_chan;
> >
> > return 0;
> > }
> > @@ -190,8 +261,17 @@ static void pci_epf_test_clean_dma_chan(struct pci_epf_test *epf_test)
> > if (!epf_test->dma_supported)
> > return;
> >
> > - dma_release_channel(epf_test->dma_chan);
> > - epf_test->dma_chan = NULL;
> > + dma_release_channel(epf_test->dma_chan_tx);
> > + if (epf_test->dma_chan_tx == epf_test->dma_chan_rx) {
> > + epf_test->dma_chan_tx = NULL;
> > + epf_test->dma_chan_rx = NULL;
> > + return;
> > + }
> > +
> > + dma_release_channel(epf_test->dma_chan_rx);
> > + epf_test->dma_chan_rx = NULL;
> > +
> > + return;
> > }
> >
> > static void pci_epf_test_print_rate(const char *ops, u64 size,
> > @@ -280,8 +360,14 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
> > goto err_map_addr;
> > }
> >
> > + if (epf_test->dma_private) {
> > + dev_err(dev, "Cannot transfer data using DMA\n");
> > + ret = -EINVAL;
> > + goto err_map_addr;
> > + }
> > +
> > ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> > - src_phys_addr, reg->size);
> > + src_phys_addr, reg->size, 0, DMA_MEM_TO_MEM);
> > if (ret)
> > dev_err(dev, "Data transfer failed\n");
> > } else {
> > @@ -363,7 +449,8 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
> >
> > ktime_get_ts64(&start);
> > ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> > - phys_addr, reg->size);
> > + phys_addr, reg->size,
> > + reg->src_addr, DMA_DEV_TO_MEM);
> > if (ret)
> > dev_err(dev, "Data transfer failed\n");
> > ktime_get_ts64(&end);
> > @@ -453,8 +540,9 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> > }
> >
> > ktime_get_ts64(&start);
> > +
> > ret = pci_epf_test_data_transfer(epf_test, phys_addr,
> > - src_phys_addr, reg->size);
> > + src_phys_addr, reg->size, reg->dst_addr, DMA_MEM_TO_DEV);
> > if (ret)
> > dev_err(dev, "Data transfer failed\n");
> > ktime_get_ts64(&end);
