Re: [PATCH v2 02/19] dmaengine: dw-edma: Add dw_edma_core_ll_clear() to clear LL control-word

[Frank Li]

On Thu, Jul 23, 2026 at 05:41:33PM +0900, Koichiro Den wrote:
> Add a core operation for clearing the control word of one linked-list
> entry. A later patch uses the operation to invalidate stale CB when
> resetting a circular LL ring.
>
> No functional change.
>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

> Changes in v2:
>   - Split the provider operation from "Clear LL data entries on reset".
>
>  drivers/dma/dw-edma/dw-edma-core.h    |  6 ++++++
>  drivers/dma/dw-edma/dw-edma-v0-core.c | 16 ++++++++++++++++
>  drivers/dma/dw-edma/dw-hdma-v0-core.c | 16 ++++++++++++++++
>  3 files changed, 38 insertions(+)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
> index e50fa7965778..089f913fd247 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -138,6 +138,7 @@ struct dw_edma_core_ops {
>  	void (*ll_data)(struct dw_edma_chan *chan, struct dw_edma_burst *burst,
>  			u32 idx, bool cb, bool irq);
>  	void (*ll_link)(struct dw_edma_chan *chan, u32 idx, bool cb, u64 addr);
> +	void (*ll_clear)(struct dw_edma_chan *chan, u32 idx);
>  	int (*ll_cur_idx)(struct dw_edma_chan *chan);
>  	void (*ch_doorbell)(struct dw_edma_chan *chan);
>  	void (*ch_enable)(struct dw_edma_chan *chan);
> @@ -255,6 +256,11 @@ dw_edma_core_ll_link(struct dw_edma_chan *chan, u32 idx, bool cb, u64 addr)
>  	chan->dw->core->ll_link(chan, idx, cb, addr);
>  }
>
> +static inline void dw_edma_core_ll_clear(struct dw_edma_chan *chan, u32 idx)
> +{
> +	chan->dw->core->ll_clear(chan, idx);
> +}
> +
>  static inline void dw_edma_core_ch_doorbell(struct dw_edma_chan *chan)
>  {
>  	chan->dw->core->ch_doorbell(chan);
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
> index ba84811234e1..c31fff095b4f 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -605,6 +605,21 @@ dw_edma_v0_core_ll_link(struct dw_edma_chan *chan, u32 idx, bool cb, u64 addr)
>  	dw_edma_v0_write_ll_link(chan, idx, control, addr);
>  }
>
> +static void dw_edma_v0_core_ll_clear(struct dw_edma_chan *chan, u32 idx)
> +{
> +	ptrdiff_t ofs = idx * sizeof(struct dw_edma_v0_lli);
> +
> +	if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) {
> +		struct dw_edma_v0_lli *lli = chan->ll_region.vaddr.mem + ofs;
> +
> +		lli->control = 0;
> +	} else {
> +		struct dw_edma_v0_lli __iomem *lli = chan->ll_region.vaddr.io + ofs;
> +
> +		writel(0, &lli->control);
> +	}
> +}
> +
>  static void dw_edma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
>  {
>  	struct dw_edma *dw = chan->dw;
> @@ -668,6 +683,7 @@ static const struct dw_edma_core_ops dw_edma_v0_core = {
>  	.handle_int = dw_edma_v0_core_handle_int,
>  	.ll_data = dw_edma_v0_core_ll_data,
>  	.ll_link = dw_edma_v0_core_ll_link,
> +	.ll_clear = dw_edma_v0_core_ll_clear,
>  	.ll_cur_idx = dw_edma_v0_core_ll_cur_idx,
>  	.ch_doorbell = dw_edma_v0_core_ch_doorbell,
>  	.ch_enable = dw_edma_v0_core_ch_enable,
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index 2fc7f8e85b43..b2d35f0b7b6d 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -374,6 +374,21 @@ dw_hdma_v0_core_ll_link(struct dw_edma_chan *chan, u32 idx, bool cb, u64 addr)
>  	dw_hdma_v0_write_ll_link(chan, idx, control, addr);
>  }
>
> +static void dw_hdma_v0_core_ll_clear(struct dw_edma_chan *chan, u32 idx)
> +{
> +	ptrdiff_t ofs = idx * sizeof(struct dw_hdma_v0_lli);
> +
> +	if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) {
> +		struct dw_hdma_v0_lli *lli = chan->ll_region.vaddr.mem + ofs;
> +
> +		lli->control = 0;
> +	} else {
> +		struct dw_hdma_v0_lli __iomem *lli = chan->ll_region.vaddr.io + ofs;
> +
> +		writel(0, &lli->control);
> +	}
> +}
> +
>  static void dw_hdma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
>  {
>  	struct dw_edma *dw = chan->dw;
> @@ -424,6 +439,7 @@ static const struct dw_edma_core_ops dw_hdma_v0_core = {
>  	.non_ll_start = dw_hdma_v0_core_non_ll_start,
>  	.ll_data = dw_hdma_v0_core_ll_data,
>  	.ll_link = dw_hdma_v0_core_ll_link,
> +	.ll_clear = dw_hdma_v0_core_ll_clear,
>  	.ll_cur_idx = dw_hdma_v0_core_ll_cur_idx,
>  	.ch_doorbell = dw_hdma_v0_core_ch_doorbell,
>  	.ch_enable = dw_hdma_v0_core_ch_enable,
> --
> 2.51.0
>