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Message-ID: <d6rtkyelnfhqya6txe7wr6rup7y6riifwzw6tbajopqa5wty6j@3o32khdidnas>
Date: Wed, 23 Jul 2025 19:26:29 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Devendra K Verma <devverma@....com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
vkoul@...nel.org
Subject: Re: [RESEND PATCH] dmaengine: dw-edma: Add Simple Mode Support
On Mon, Jun 23, 2025 at 11:47:33AM GMT, Devendra K Verma wrote:
> The HDMA IP supports the simple mode (non-linked list).
> In this mode the channel registers are configured to initiate
> a single DMA data transfer. The channel can be configured in
> simple mode via peripheral param of dma_slave_config param.
>
> Signed-off-by: Devendra K Verma <devverma@....com>
> ---
> drivers/dma/dw-edma/dw-edma-core.c | 10 +++++
> drivers/dma/dw-edma/dw-edma-core.h | 2 +
> drivers/dma/dw-edma/dw-hdma-v0-core.c | 53 ++++++++++++++++++++++++++-
> include/linux/dma/edma.h | 8 ++++
> 4 files changed, 72 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index c2b88cc99e5d..4dafd6554277 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -235,9 +235,19 @@ static int dw_edma_device_config(struct dma_chan *dchan,
> struct dma_slave_config *config)
> {
> struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> + struct dw_edma_peripheral_config *pconfig = config->peripheral_config;
> + unsigned long flags;
> +
> + if (WARN_ON(config->peripheral_config &&
> + config->peripheral_size != sizeof(*pconfig)))
> + return -EINVAL;
>
> + spin_lock_irqsave(&chan->vc.lock, flags);
> memcpy(&chan->config, config, sizeof(*config));
> +
> + chan->non_ll_en = pconfig ? pconfig->non_ll_en : false;
Who is allocating 'dw_edma_peripheral_config' and setting 'non_ll_en' flag? We
cannot introduce a flag without anyone using it in upstream.
- Mani
> chan->configured = true;
> + spin_unlock_irqrestore(&chan->vc.lock, flags);
>
> return 0;
> }
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
> index 71894b9e0b15..c0266976aa22 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -86,6 +86,8 @@ struct dw_edma_chan {
> u8 configured;
>
> struct dma_slave_config config;
> +
> + bool non_ll_en;
> };
>
> struct dw_edma_irq {
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index e3f8db4fe909..3237c807a18e 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -225,7 +225,7 @@ static void dw_hdma_v0_sync_ll_data(struct dw_edma_chunk *chunk)
> readl(chunk->ll_region.vaddr.io);
> }
>
> -static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> +static void dw_hdma_v0_ll_start(struct dw_edma_chunk *chunk, bool first)
> {
> struct dw_edma_chan *chan = chunk->chan;
> struct dw_edma *dw = chan->dw;
> @@ -263,6 +263,57 @@ static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START);
> }
>
> +static void dw_hdma_v0_non_ll_start(struct dw_edma_chunk *chunk)
> +{
> + struct dw_edma_chan *chan = chunk->chan;
> + struct dw_edma *dw = chan->dw;
> + struct dw_edma_burst *child;
> + u32 val;
> +
> + list_for_each_entry(child, &chunk->burst->list, list) {
> + SET_CH_32(dw, chan->dir, chan->id, ch_en, BIT(0));
> +
> + /* Source address */
> + SET_CH_32(dw, chan->dir, chan->id, sar.lsb, lower_32_bits(child->sar));
> + SET_CH_32(dw, chan->dir, chan->id, sar.msb, upper_32_bits(child->sar));
> +
> + /* Destination address */
> + SET_CH_32(dw, chan->dir, chan->id, dar.lsb, lower_32_bits(child->dar));
> + SET_CH_32(dw, chan->dir, chan->id, dar.msb, upper_32_bits(child->dar));
> +
> + /* Transfer size */
> + SET_CH_32(dw, chan->dir, chan->id, transfer_size, child->sz);
> +
> + /* Interrupt setup */
> + val = GET_CH_32(dw, chan->dir, chan->id, int_setup) |
> + HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK |
> + HDMA_V0_LOCAL_STOP_INT_EN | HDMA_V0_LOCAL_ABORT_INT_EN;
> +
> + if (!(dw->chip->flags & DW_EDMA_CHIP_LOCAL))
> + val |= HDMA_V0_REMOTE_STOP_INT_EN | HDMA_V0_REMOTE_ABORT_INT_EN;
> +
> + SET_CH_32(dw, chan->dir, chan->id, int_setup, val);
> +
> + /* Channel control setup */
> + val = GET_CH_32(dw, chan->dir, chan->id, control1);
> + val &= ~HDMA_V0_LINKLIST_EN;
> + SET_CH_32(dw, chan->dir, chan->id, control1, val);
> +
> + /* Ring the doorbell */
> + SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START);
> + }
> +}
> +
> +static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> +{
> + struct dw_edma_chan *chan = chunk->chan;
> +
> + if (!chan->non_ll_en)
> + dw_hdma_v0_ll_start(chunk, first);
> + else
> + dw_hdma_v0_non_ll_start(chunk);
> +}
> +
> static void dw_hdma_v0_core_ch_config(struct dw_edma_chan *chan)
> {
> struct dw_edma *dw = chan->dw;
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 3080747689f6..82d808013a66 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -101,6 +101,14 @@ struct dw_edma_chip {
> struct dw_edma *dw;
> };
>
> +/**
> + * struct dw_edma_peripheral_config - peripheral spicific configurations
> + * @non_ll_en: enable non-linked list mode of operations
> + */
> +struct dw_edma_peripheral_config {
> + bool non_ll_en;
> +};
> +
> /* Export to the platform drivers */
> #if IS_REACHABLE(CONFIG_DW_EDMA)
> int dw_edma_probe(struct dw_edma_chip *chip);
> --
> 2.43.0
>
--
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