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Date: Mon, 14 Feb 2022 15:19:19 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc: Kishon Vijay Abraham I <kishon@...com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Krzysztof Wilczyński <kw@...ux.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Marek Vasut <marek.vasut+renesas@...il.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
Rob Herring <robh@...nel.org>, linux-pci@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
Prabhakar <prabhakar.csengg@...il.com>,
Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [RFC PATCH 2/5] PCI: endpoint: Add support to data transfer
using internal dmac
On Wed, Jan 26, 2022 at 07:50:40PM +0000, Lad Prabhakar wrote:
> For PCIe EP capable with internal DMAC, transfer data using this
> when -d option is used with pcitest.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> drivers/pci/endpoint/functions/pci-epf-test.c | 184 ++++++++++++++----
> 1 file changed, 141 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 90d84d3bc868..f792b1a15c44 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -55,6 +55,7 @@ struct pci_epf_test {
> struct dma_chan *dma_chan;
> struct completion transfer_complete;
> bool dma_supported;
> + bool internal_dmac;
Please use "dma" everywhere.
> const struct pci_epc_features *epc_features;
> };
>
> @@ -148,6 +149,40 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> return 0;
> }
>
> +/**
> + * pci_epf_test_internal_dmac_data_transfer() - Function that uses internal DMAC
> + * to transfer data between PCIe EP and remote PCIe RC
> + * @epf_test: the EPF test device that performs the data transfer operation
> + * @dma_dst: The destination address of the data transfer. It can be a physical
> + * address given by pci_epc_mem_alloc_addr or DMA mapping APIs.
> + * @dma_src: The source address of the data transfer. It can be a physical
> + * address given by pci_epc_mem_alloc_addr or DMA mapping APIs.
> + * @len: The size of the data transfer
> + * @dir: Direction of data transfer
> + *
> + * Function that uses internal dmac supported by the controller to transfer data
> + * between PCIe EP and remote PCIe RC.
> + *
> + * The function returns '0' on success and negative value on failure.
> + */
> +static int
> +pci_epf_test_internal_dmac_data_transfer(struct pci_epf_test *epf_test,
> + dma_addr_t dma_dst, dma_addr_t dma_src,
> + size_t len, enum pci_epf_xfr_direction dir)
> +{
> + struct pci_epf *epf = epf_test->epf;
> + int ret;
> +
> + if (!epf_test->internal_dmac)
> + return -EINVAL;
> +
> + ret = pci_epf_internal_dmac_xfr(epf, dma_dst, dma_src, len, dir);
> + if (ret)
> + return -EIO;
Why can't you return "ret"?
> +
> + return 0;
> +}
> +
> /**
> * pci_epf_test_init_dma_chan() - Function to initialize EPF test DMA channel
> * @epf_test: the EPF test device that performs data transfer operation
> @@ -238,6 +273,14 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
> struct pci_epc *epc = epf->epc;
> enum pci_barno test_reg_bar = epf_test->test_reg_bar;
> struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> + bool internal_dmac = epf_test->internal_dmac;
> +
> + use_dma = !!(reg->flags & FLAG_USE_DMA);
> +
> + if (use_dma && internal_dmac) {
> + dev_err(dev, "Operation not supported\n");
Here you are erroring out but below you are checking for this condition to do
internal DMA transfer.
> + return -EINVAL;
> + }
>
> src_addr = pci_epc_mem_alloc_addr(epc, &src_phys_addr, reg->size);
> if (!src_addr) {
> @@ -272,7 +315,6 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
Why internal DMA is not used in pci_epf_test_copy()?
> }
>
> ktime_get_ts64(&start);
> - use_dma = !!(reg->flags & FLAG_USE_DMA);
> if (use_dma) {
> if (!epf_test->dma_supported) {
> dev_err(dev, "Cannot transfer data using DMA\n");
> @@ -322,31 +364,49 @@ 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];
> + bool internal_dmac = epf_test->internal_dmac;
>
> - src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> - if (!src_addr) {
> - dev_err(dev, "Failed to allocate address\n");
> - reg->status = STATUS_SRC_ADDR_INVALID;
> - ret = -ENOMEM;
> - goto err;
> - }
> + use_dma = !!(reg->flags & FLAG_USE_DMA);
>
> - ret = pci_epc_map_addr(epc, epf->func_no, epf->vfunc_no, phys_addr,
> - reg->src_addr, reg->size);
> - if (ret) {
> - dev_err(dev, "Failed to map address\n");
> - reg->status = STATUS_SRC_ADDR_INVALID;
> - goto err_addr;
> + if (use_dma && internal_dmac) {
Both are mutually exclusive, isn't it?
> + phys_addr = reg->src_addr;
> + src_addr = NULL;
> + } else {
> + src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> + if (!src_addr) {
> + dev_err(dev, "Failed to allocate address\n");
> + reg->status = STATUS_SRC_ADDR_INVALID;
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + ret = pci_epc_map_addr(epc, epf->func_no, epf->vfunc_no, phys_addr,
> + reg->src_addr, reg->size);
> + if (ret) {
> + dev_err(dev, "Failed to map address\n");
> + reg->status = STATUS_SRC_ADDR_INVALID;
> + goto err_addr;
> + }
> }
>
[...]
>
> ret = pci_epf_test_alloc_space(epf);
> if (ret)
> @@ -868,11 +964,13 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> return ret;
> }
>
> - epf_test->dma_supported = true;
> + epf_test->dma_supported = false;
>
> - ret = pci_epf_test_init_dma_chan(epf_test);
> - if (ret)
> - epf_test->dma_supported = false;
> + if (!epf_test->internal_dmac) {
> + ret = pci_epf_test_init_dma_chan(epf_test);
> + if (!ret)
> + epf_test->dma_supported = true;
You can set this flag to true inside pci_epf_test_init_dma_chan().
Thanks,
Mani
> + }
>
> if (linkup_notifier) {
> epf->nb.notifier_call = pci_epf_test_notifier;
> --
> 2.25.1
>
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