Re: [PATCH v4 14/14] dmaengine: dw-edma: Program endpoint function numbers
From: Frank Li
Date: Tue Jul 14 2026 - 15:54:50 EST
On Fri, Jul 10, 2026 at 05:15:18PM +0900, Koichiro Den wrote:
> The eDMA/HDMA transfers the driver issues carry a requester function
> number in their TLPs, but nothing ever programs it: eDMA v0 leaves the
> FUNC_NUM field of the channel control word zero and HDMA leaves the
> per-channel func_num register at its reset value, so every transfer is
> attributed to function 0. That is invisible in single-function setups,
> but once the DMA block serves a non-zero endpoint function, its
> requests must carry that function's number for the host to attribute
> and translate them correctly.
>
> Record the function number in the chip data (PCI_FUNC() of the probing
> device for dw-edma-pcie) and program it per channel.
>
> Endpoint-local chip instances keep func_no at 0, so transfers issued by
> the endpoint-side driver remain PF0-attributed. Delegated channels are
> programmed by the host-side dw-edma-pcie instance when it takes over the
> channel, using that instance's PCI_FUNC().
>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> Changes in v4:
> - New patch in v4.
>
> drivers/dma/dw-edma/dw-edma-core.c | 1 +
> drivers/dma/dw-edma/dw-edma-core.h | 1 +
> drivers/dma/dw-edma/dw-edma-pcie.c | 1 +
> drivers/dma/dw-edma/dw-edma-v0-core.c | 10 +++++++++-
> drivers/dma/dw-edma/dw-hdma-v0-core.c | 3 +++
> drivers/dma/dw-edma/dw-hdma-v0-regs.h | 1 +
> include/linux/dma/edma.h | 2 ++
> 7 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 0d38de4480a0..d1af44124075 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -1016,6 +1016,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
> chan = &dw->chan[i];
>
> chan->dw = dw;
> + chan->func_no = chip->func_no;
>
> if (i < dw->wr_ch_cnt) {
> chan->id = i;
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
> index 8657275d2484..1cf95ab27071 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -78,6 +78,7 @@ struct dw_edma_chan {
> struct dw_edma *dw;
> int id;
> enum dw_edma_dir dir;
> + u8 func_no;
>
> u32 ll_max;
>
> diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
> index c1585c8ce11f..bb477dc0fb03 100644
> --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> @@ -473,6 +473,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>
> chip->mf = dma_data->mf;
> chip->flags = match->chip_flags;
> + chip->func_no = PCI_FUNC(pdev->devfn);
> chip->nr_irqs = nr_irqs;
> chip->ops = match->plat_ops;
> chip->cfg_non_ll = dma_data->cfg_non_ll;
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
> index 32df5d13ba8b..441fa8f67d5a 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -25,6 +25,8 @@ enum dw_edma_control {
> DW_EDMA_V0_LLE = BIT(9),
> };
>
> +#define EDMA_V0_FUNC_NUM_MASK GENMASK(16, 12)
> +
> static inline struct dw_edma_v0_regs __iomem *__dw_regs(struct dw_edma *dw)
> {
> return dw->chip->reg_base;
> @@ -159,6 +161,11 @@ static inline u32 readl_ch(struct dw_edma *dw, enum dw_edma_dir dir, u16 ch,
> #define GET_CH_32(dw, dir, ch, name) \
> readl_ch(dw, dir, ch, &(__dw_ch_regs(dw, dir, ch)->name))
>
> +static u32 dw_edma_v0_func_num(struct dw_edma_chan *chan)
> +{
> + return FIELD_PREP(EDMA_V0_FUNC_NUM_MASK, chan->func_no);
> +}
> +
> /* eDMA management callbacks */
> static void dw_edma_v0_core_dir_off(struct dw_edma *dw, enum dw_edma_dir dir)
> {
> @@ -474,7 +481,8 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
>
> /* Channel control */
> SET_CH_32(dw, chan->dir, chan->id, ch_control1,
> - (DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));
> + DW_EDMA_V0_CCS | DW_EDMA_V0_LLE |
> + dw_edma_v0_func_num(chan));
> /* Linked list */
> /* llp is not aligned on 64bit -> keep 32bit accesses */
> SET_CH_32(dw, chan->dir, chan->id, llp.lsb,
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index be22f9f811ca..ea9f18c8d707 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -375,6 +375,9 @@ static void dw_hdma_v0_core_ch_config(struct dw_edma_chan *chan)
> SET_CH_32(dw, chan->dir, chan->id, msi_abort.msb, chan->msi.address_hi);
> /* config MSI data */
> SET_CH_32(dw, chan->dir, chan->id, msi_msgdata, chan->msi.data);
> + /* Configure the requester function number used by outbound TLPs. */
> + SET_CH_32(dw, chan->dir, chan->id, func_num,
> + FIELD_PREP(HDMA_V0_FUNC_NUM_PF_MASK, chan->func_no));
> }
>
> /* HDMA debugfs callbacks */
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-regs.h b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> index 7759ba9b4850..2bbcc7fabb0a 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> @@ -24,6 +24,7 @@
> #define HDMA_V0_CONSUMER_CYCLE_BIT BIT(0)
> #define HDMA_V0_DOORBELL_START BIT(0)
> #define HDMA_V0_CH_STATUS_MASK GENMASK(1, 0)
> +#define HDMA_V0_FUNC_NUM_PF_MASK GENMASK(7, 0)
>
> struct dw_hdma_v0_ch_regs {
> u32 ch_en; /* 0x0000 */
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 3c33d12d1cdb..64044451d182 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -116,6 +116,7 @@ enum dw_edma_ch_irq_mode {
> * @db_irq: Virtual IRQ dedicated to interrupt emulation
> * @db_offset: Offset from DMA register base
> * @mf: DMA register map format
> + * @func_no: PCI endpoint function number used by DMA TLPs
> * @dw: struct dw_edma that is filled by dw_edma_probe()
> */
> struct dw_edma_chip {
> @@ -141,6 +142,7 @@ struct dw_edma_chip {
> resource_size_t db_offset;
>
> enum dw_edma_map_format mf;
> + u8 func_no;
>
> struct dw_edma *dw;
> bool cfg_non_ll;
> --
> 2.51.0
>