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From:   Alan Mikhak <alan.mikhak@sifive.com>
Date:   Mon, 11 May 2020 11:02:23 -0700
Message-ID: <CABEDWGxhCCrVT4Dj=o+9sKtL1EvrOZjNkyuXqYYcZoQ8b-aXEg@mail.gmail.com>
Subject: Re: [PATCH] PCI: endpoint: functions/pci-epf-test: Support slave DMA transfer
To:     Rob Herring <robh@kernel.org>
Cc:     linux-pci <linux-pci@vger.kernel.org>,
        linux-kernel@vger.kernel.org,
        Kishon Vijay Abraham I <kishon@ti.com>,
        lorenzo.pieralisi@arm.com, Bjorn Helgaas <bhelgaas@google.com>,
        efremov@linux.com, b.zolnierkie@samsung.com, vidyas@nvidia.com,
        Paul Walmsley <paul.walmsley@sifive.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Thu, May 7, 2020 at 2:44 PM Rob Herring <robh@kernel.org> wrote:
>
> On Fri, May 01, 2020 at 05:29:12PM -0700, Alan Mikhak wrote:
> > From: Alan Mikhak <alan.mikhak@sifive.com>
> >
> > Modify pci_epf_test_data_transfer() to also support slave DMA transfers.
> > Adds a direction parameter so caller can specify one of the supported DMA
> > transfer directions: DMA_MEM_TO_MEM, DMA_MEM_TO_DEV, and DMA_DEV_TO_MEM.
> > For DMA_MEM_TO_MEM, the function calls dmaengine_prep_dma_memcpy() as it
> > did before. For DMA_MEM_TO_DEV or DMA_DEV_TO_MEM direction, the function
> > calls dmaengine_slave_config() to configure the slave channel before it
> > calls dmaengine_prep_slave_single().
> >
> > Modify existing callers to specify DMA_MEM_TO_MEM since that is the only
> > possible option so far. Rename the phys_addr local variable in some of the
> > callers for more readability. Tighten some of the timing function calls to
> > avoid counting error print time in case of error.
>
> Looks fine, but also needs a user. The last sentence sounds like a
> separate change.

Thanks Rob for your comment.

I will address your concern in a future v2 patch.

Regards,
Alan

>
> >
> > Signed-off-by: Alan Mikhak <alan.mikhak@sifive.com>
> > ---
> >  drivers/pci/endpoint/functions/pci-epf-test.c | 67 ++++++++++++++++++---------
> >  1 file changed, 44 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index 60330f3e3751..1d026682febb 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -104,25 +104,41 @@ static void pci_epf_test_dma_callback(void *param)
> >   * The function returns '0' on success and negative value on failure.
> >   */
> >  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)
> > +                                   dma_addr_t dma_dst,
> > +                                   dma_addr_t dma_src,
> > +                                   size_t len,
> > +                                   enum dma_transfer_direction dir)
> >  {
> >       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_slave_config sconf;
> >       struct dma_async_tx_descriptor *tx;
> >       struct device *dev = &epf->dev;
> >       dma_cookie_t cookie;
> > +     dma_addr_t buf;
> >       int ret;
> >
> >       if (IS_ERR_OR_NULL(chan)) {
> > -             dev_err(dev, "Invalid DMA memcpy channel\n");
> > +             dev_err(dev, "Invalid DMA channel\n");
> >               return -EINVAL;
> >       }
> >
> > -     tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
> > +     if (dir == DMA_MEM_TO_MEM) {
> > +             tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src,
> > +                                            len, flags);
> > +     } else {
> > +             memset(&sconf, 0, sizeof(sconf));
> > +             sconf.direction = dir;
> > +             sconf.dst_addr = dma_dst;
> > +             sconf.src_addr = dma_src;
> > +             dmaengine_slave_config(chan, &sconf);
> > +
> > +             buf = (dir == DMA_MEM_TO_DEV) ? dma_dst : dma_src;
> > +             tx = dmaengine_prep_slave_single(chan, buf, len, dir, flags);
> > +     }
> >       if (!tx) {
> > -             dev_err(dev, "Failed to prepare DMA memcpy\n");
> > +             dev_err(dev, "Failed to prepare DMA transfer\n");
> >               return -EIO;
> >       }
> >
> > @@ -268,7 +284,6 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
> >               goto err_dst_addr;
> >       }
> >
> > -     ktime_get_ts64(&start);
> >       use_dma = !!(reg->flags & FLAG_USE_DMA);
> >       if (use_dma) {
> >               if (!epf_test->dma_supported) {
> > @@ -277,14 +292,18 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
> >                       goto err_map_addr;
> >               }
> >
> > +             ktime_get_ts64(&start);
> >               ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> > -                                              src_phys_addr, reg->size);
> > +                                              src_phys_addr, reg->size,
> > +                                              DMA_MEM_TO_MEM);
> > +             ktime_get_ts64(&end);
> >               if (ret)
> >                       dev_err(dev, "Data transfer failed\n");
> >       } else {
> > +             ktime_get_ts64(&start);
> >               memcpy(dst_addr, src_addr, reg->size);
> > +             ktime_get_ts64(&end);
> >       }
> > -     ktime_get_ts64(&end);
> >       pci_epf_test_print_rate("COPY", reg->size, &start, &end, use_dma);
> >
> >  err_map_addr:
> > @@ -310,7 +329,7 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
> >       void *buf;
> >       u32 crc32;
> >       bool use_dma;
> > -     phys_addr_t phys_addr;
> > +     phys_addr_t src_phys_addr;
> >       phys_addr_t dst_phys_addr;
> >       struct timespec64 start, end;
> >       struct pci_epf *epf = epf_test->epf;
> > @@ -319,8 +338,9 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
> >       struct device *dma_dev = epf->epc->dev.parent;
> >       enum pci_barno test_reg_bar = epf_test->test_reg_bar;
> >       struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> > +     enum dma_transfer_direction dir = DMA_MEM_TO_MEM;
> >
> > -     src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> > +     src_addr = pci_epc_mem_alloc_addr(epc, &src_phys_addr, reg->size);
> >       if (!src_addr) {
> >               dev_err(dev, "Failed to allocate address\n");
> >               reg->status = STATUS_SRC_ADDR_INVALID;
> > @@ -328,7 +348,7 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
> >               goto err;
> >       }
> >
> > -     ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, reg->src_addr,
> > +     ret = pci_epc_map_addr(epc, epf->func_no, src_phys_addr, reg->src_addr,
> >                              reg->size);
> >       if (ret) {
> >               dev_err(dev, "Failed to map address\n");
> > @@ -360,10 +380,10 @@ 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);
> > +                                              src_phys_addr, reg->size, dir);
> > +             ktime_get_ts64(&end);
> >               if (ret)
> >                       dev_err(dev, "Data transfer failed\n");
> > -             ktime_get_ts64(&end);
> >
> >               dma_unmap_single(dma_dev, dst_phys_addr, reg->size,
> >                                DMA_FROM_DEVICE);
> > @@ -383,10 +403,10 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
> >       kfree(buf);
> >
> >  err_map_addr:
> > -     pci_epc_unmap_addr(epc, epf->func_no, phys_addr);
> > +     pci_epc_unmap_addr(epc, epf->func_no, src_phys_addr);
> >
> >  err_addr:
> > -     pci_epc_mem_free_addr(epc, phys_addr, src_addr, reg->size);
> > +     pci_epc_mem_free_addr(epc, src_phys_addr, src_addr, reg->size);
> >
> >  err:
> >       return ret;
> > @@ -398,7 +418,7 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> >       void __iomem *dst_addr;
> >       void *buf;
> >       bool use_dma;
> > -     phys_addr_t phys_addr;
> > +     phys_addr_t dst_phys_addr;
> >       phys_addr_t src_phys_addr;
> >       struct timespec64 start, end;
> >       struct pci_epf *epf = epf_test->epf;
> > @@ -407,8 +427,9 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> >       struct device *dma_dev = epf->epc->dev.parent;
> >       enum pci_barno test_reg_bar = epf_test->test_reg_bar;
> >       struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> > +     enum dma_transfer_direction dir = DMA_MEM_TO_MEM;
> >
> > -     dst_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> > +     dst_addr = pci_epc_mem_alloc_addr(epc, &dst_phys_addr, reg->size);
> >       if (!dst_addr) {
> >               dev_err(dev, "Failed to allocate address\n");
> >               reg->status = STATUS_DST_ADDR_INVALID;
> > @@ -416,7 +437,7 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> >               goto err;
> >       }
> >
> > -     ret = pci_epc_map_addr(epc, epf->func_no, phys_addr, reg->dst_addr,
> > +     ret = pci_epc_map_addr(epc, epf->func_no, dst_phys_addr, reg->dst_addr,
> >                              reg->size);
> >       if (ret) {
> >               dev_err(dev, "Failed to map address\n");
> > @@ -450,11 +471,11 @@ 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);
> > +             ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> > +                                              src_phys_addr, reg->size, dir);
> > +             ktime_get_ts64(&end);
> >               if (ret)
> >                       dev_err(dev, "Data transfer failed\n");
> > -             ktime_get_ts64(&end);
> >
> >               dma_unmap_single(dma_dev, src_phys_addr, reg->size,
> >                                DMA_TO_DEVICE);
> > @@ -476,10 +497,10 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> >       kfree(buf);
> >
> >  err_map_addr:
> > -     pci_epc_unmap_addr(epc, epf->func_no, phys_addr);
> > +     pci_epc_unmap_addr(epc, epf->func_no, dst_phys_addr);
> >
> >  err_addr:
> > -     pci_epc_mem_free_addr(epc, phys_addr, dst_addr, reg->size);
> > +     pci_epc_mem_free_addr(epc, dst_phys_addr, dst_addr, reg->size);
> >
> >  err:
> >       return ret;
> > --
> > 2.7.4
> >