From: Frank Li <Frank.li@oss.nxp.com>
To: Koichiro Den <den@valinux.co.jp>
Cc: "Manivannan Sadhasivam" <mani@kernel.org>,
"Vinod Koul" <vkoul@kernel.org>, "Frank Li" <Frank.Li@kernel.org>,
"Gustavo Pimentel" <Gustavo.Pimentel@synopsys.com>,
"Kees Cook" <kees@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Christoph Hellwig" <hch@lst.de>,
"Serge Semin" <fancer.lancer@gmail.com>,
"Cai Huoqing" <cai.huoqing@linux.dev>,
"Niklas Cassel" <cassel@kernel.org>,
"Devendra K Verma" <devendra.verma@amd.com>,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 01/19] dmaengine: dw-edma: Add dw_edma_core_ll_cur_idx() to get current LL entry index
Date: Thu, 23 Jul 2026 11:25:07 -0500 [thread overview]
Message-ID: <amJAY8lV6WbigHOj@SMW015318> (raw)
In-Reply-To: <20260723084150.521366-2-den@valinux.co.jp>
On Thu, Jul 23, 2026 at 05:41:32PM +0900, Koichiro Den wrote:
> From: Frank Li <Frank.Li@nxp.com>
>
> Add dw_edma_core_ll_cur_idx() to get the current LL entry index and
> prepare for dynamic addition of DMA requests while the DMA engine is
> running.
>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> Co-developed-by: Koichiro Den <den@valinux.co.jp>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Based on Frank's original submission:
> https://lore.kernel.org/dmaengine/20260109-edma_dymatic-v1-1-9a98c9c98536@nxp.com/
>
> Changes in v2:
> - Handle zero low words and low-word wrap without reading DMA_LLP.MSB
> on the normal path, and clarify the lost-context comments.
>
> drivers/dma/dw-edma/dw-edma-core.h | 10 ++++++++++
> drivers/dma/dw-edma/dw-edma-v0-core.c | 19 +++++++++++++++++++
> drivers/dma/dw-edma/dw-hdma-v0-core.c | 19 +++++++++++++++++++
> 3 files changed, 48 insertions(+)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
> index f6a5ad317567..e50fa7965778 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);
> + 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);
> void (*ch_config)(struct dw_edma_chan *chan);
> @@ -181,6 +182,15 @@ struct dw_edma_chan *dchan2dw_edma_chan(struct dma_chan *dchan)
> return vc2dw_edma_chan(to_virt_chan(dchan));
> }
>
> +/*
> + * Return the current LL entry index. A negative value means that the channel
> + * context is not initialized or was lost after a link reset.
> + */
> +static inline int dw_edma_core_ll_cur_idx(struct dw_edma_chan *chan)
> +{
> + return chan->dw->core->ll_cur_idx(chan);
> +}
> +
> static inline u64 dw_edma_core_get_ll_paddr(struct dw_edma_chan *chan)
> {
> if (chan->dir == EDMA_DIR_WRITE)
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
> index abc1bd4c0be2..ba84811234e1 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -616,6 +616,24 @@ static void dw_edma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
> FIELD_PREP(EDMA_V0_DOORBELL_CH_MASK, chan->id));
> }
>
> +static int dw_edma_v0_core_ll_cur_idx(struct dw_edma_chan *chan)
> +{
> + u32 base, val;
> +
> + val = GET_CH_32(chan->dw, chan->dir, chan->id, llp.lsb);
> + base = lower_32_bits(dw_edma_core_get_ll_paddr(chan));
> +
> + /*
> + * An all-zero pointer means that the channel context is unavailable,
> + * so an LL region starting at DMA address zero is not supported.
> + */
> + if (!val && !GET_CH_32(chan->dw, chan->dir, chan->id, llp.msb))
> + return -EINVAL;
> +
> + /* u32 subtraction handles a low-word wrap at a 4 GiB boundary. */
> + return (val - base) / EDMA_LL_SZ;
> +}
> +
> /* eDMA debugfs callbacks */
> static void dw_edma_v0_core_debugfs_on(struct dw_edma *dw)
> {
> @@ -650,6 +668,7 @@ 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_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,
> .ch_config = dw_edma_v0_core_ch_config,
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index 36ee72efcd31..2fc7f8e85b43 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -384,6 +384,24 @@ static void dw_hdma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
> SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START);
> }
>
> +static int dw_hdma_v0_core_ll_cur_idx(struct dw_edma_chan *chan)
> +{
> + u32 base, val;
> +
> + val = GET_CH_32(chan->dw, chan->dir, chan->id, llp.lsb);
> + base = lower_32_bits(dw_edma_core_get_ll_paddr(chan));
> +
> + /*
> + * An all-zero pointer means that the channel context is unavailable,
> + * so an LL region starting at DMA address zero is not supported.
> + */
> + if (!val && !GET_CH_32(chan->dw, chan->dir, chan->id, llp.msb))
> + return -EINVAL;
> +
> + /* u32 subtraction handles a low-word wrap at a 4 GiB boundary. */
> + return (val - base) / EDMA_LL_SZ;
> +}
> +
> /* HDMA debugfs callbacks */
> static void dw_hdma_v0_core_debugfs_on(struct dw_edma *dw)
> {
> @@ -406,6 +424,7 @@ 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_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,
> .ch_config = dw_hdma_v0_core_ch_config,
> --
> 2.51.0
>
next prev parent reply other threads:[~2026-07-23 16:25 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-23 8:41 [PATCH v2 00/19] dmaengine: dw-edma: Support dynamic LL appends Koichiro Den
2026-07-23 8:41 ` [PATCH v2 01/19] dmaengine: dw-edma: Add dw_edma_core_ll_cur_idx() to get current LL entry index Koichiro Den
2026-07-23 16:25 ` Frank Li [this message]
2026-07-23 8:41 ` [PATCH v2 02/19] dmaengine: dw-edma: Add dw_edma_core_ll_clear() to clear LL control-word Koichiro Den
2026-07-23 8:41 ` [PATCH v2 03/19] dmaengine: dw-edma: Factor out linked-list transfer start Koichiro Den
2026-07-23 16:31 ` Frank Li
2026-07-23 8:41 ` [PATCH v2 04/19] dmaengine: dw-edma: Make DMA link list work as a circular buffer Koichiro Den
2026-07-23 9:07 ` sashiko-bot
2026-07-23 16:43 ` Frank Li
2026-07-23 8:41 ` [PATCH v2 05/19] dmaengine: dw-edma: Add LL interrupt placement policy Koichiro Den
2026-07-23 8:41 ` [PATCH v2 06/19] dmaengine: dw-edma: Move callback result helper before LL helpers Koichiro Den
2026-07-23 16:51 ` Frank Li
2026-07-23 8:41 ` [PATCH v2 07/19] dmaengine: dw-edma: Dispatch DONE interrupts by channel request Koichiro Den
2026-07-23 8:55 ` sashiko-bot
2026-07-23 16:57 ` Frank Li
2026-07-23 8:41 ` [PATCH v2 08/19] dmaengine: dw-edma: Centralize LL doorbell decisions Koichiro Den
2026-07-23 9:09 ` sashiko-bot
2026-07-23 17:02 ` Frank Li
2026-07-23 8:41 ` [PATCH v2 09/19] dmaengine: dw-edma: Reclaim issued descriptors from IRQ-paired LL progress Koichiro Den
2026-07-23 9:01 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 10/19] dmaengine: dw-edma: Use HDMA watermarks as progress events Koichiro Den
2026-07-23 8:41 ` [PATCH v2 11/19] dmaengine: dw-edma: Reconcile lost completions from a stopped LLP re-sample Koichiro Den
2026-07-23 8:41 ` [PATCH v2 12/19] dmaengine: dw-edma: Recover stopped channels from tx_status() Koichiro Den
2026-07-23 8:59 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 13/19] dmaengine: dw-edma: Make the LL ring reset a full channel resync Koichiro Den
2026-07-23 9:10 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 14/19] dmaengine: dw-edma: Reset LL state after terminate and abort Koichiro Den
2026-07-23 9:14 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 15/19] dmaengine: dw-edma: Add engine reset and enable operations Koichiro Den
2026-07-23 9:11 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 16/19] dmaengine: dw-edma: Add engine recovery infrastructure Koichiro Den
2026-07-23 9:14 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 17/19] dmaengine: dw-edma: Detect and recover a stalled eDMA engine Koichiro Den
2026-07-23 9:12 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 18/19] dmaengine: dw-edma: Dynamically append requests while running Koichiro Den
2026-07-23 8:41 ` [PATCH v2 19/19] dmaengine: dw-edma: Add trace support Koichiro Den
2026-07-23 9:11 ` sashiko-bot
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