Re: [PATCH v5 02/12] dmaengine: add DMA_PREP_LOCK and DMA_PREP_UNLOCK flag

Vinod Koul
2024-12-24T10:34:20Z

On 12-12-24, 09:46, Md Sadre Alam wrote:
> Add lock and unlock flag support on command descriptor.
> Once lock set in requester pipe, then the bam controller
> will lock all others pipe and process the request only
> from requester pipe. Unlocking only can be performed from
> the same pipe.
>
> If DMA_PREP_LOCK flag passed in command descriptor then requester
> of this transaction wanted to lock the BAM controller for this
> transaction so BAM driver should set LOCK bit for the HW descriptor.
>
> If DMA_PREP_UNLOCK flag passed in command descriptor then requester
> of this transaction wanted to unlock the BAM controller.so BAM driver
> should set UNLOCK bit for the HW descriptor.
>
> BAM IP version 1.4.0 and above only supports this LOCK/UNLOCK
> feature.
>
> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
> ---
>
> Change in [v5]
>
> * Added DMA_PREP_LOCK and DMA_PREP_UNLOCK flag support
>
> Change in [v4]
>
> * This patch was not included in v4
>
> Change in [v3]
>
> * This patch was not included in v3
>
> Change in [v2]
>
> * This patch was not included in v2
>
> Change in [v1]
>
> * This patch was not included in v1
>
> Documentation/driver-api/dmaengine/provider.rst | 15 +++++++++++++++
> include/linux/dmaengine.h | 6 ++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
> index 3085f8b460fa..5f30c20f94f3 100644
> --- a/Documentation/driver-api/dmaengine/provider.rst
> +++ b/Documentation/driver-api/dmaengine/provider.rst
> @@ -628,6 +628,21 @@ DMA_CTRL_REUSE
> - This flag is only supported if the channel reports the DMA_LOAD_EOT
> capability.
>
> +- DMA_PREP_LOCK
> +
> + - If set, the BAM will lock all other pipes not related to the current

Why BAM, the generic API _cannot_ be implementation specific, make this
as a generic one please

Anyone can use this new method and not just BAM...

> + pipe group, and keep handling the current pipe only.
> +
> + - All pipes not within this group will be locked by this pipe upon lock
> + event.
> +
> + - only pipes which are in the same group and relate to the same Environment
> + Execution(EE) will not be locked by a certain pipe.
> +
> +- DMA_PREP_UNLOCK
> +
> + - If set, BAM will release all locked pipes
> +
> General Design Notes
> ====================
>
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 346251bf1026..8ebd43a998a7 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -200,6 +200,10 @@ struct dma_vec {
> * transaction is marked with DMA_PREP_REPEAT will cause the new transaction
> * to never be processed and stay in the issued queue forever. The flag is
> * ignored if the previous transaction is not a repeated transaction.
> + * @DMA_PREP_LOCK: tell the driver that there is a lock bit set on command
> + * descriptor.
> + * @DMA_PREP_UNLOCK: tell the driver that there is a un-lock bit set on command
> + * descriptor.
> */
> enum dma_ctrl_flags {
> DMA_PREP_INTERRUPT = (1 << 0),
> @@ -212,6 +216,8 @@ enum dma_ctrl_flags {
> DMA_PREP_CMD = (1 << 7),
> DMA_PREP_REPEAT = (1 << 8),
> DMA_PREP_LOAD_EOT = (1 << 9),
> + DMA_PREP_LOCK = (1 << 10),
> + DMA_PREP_UNLOCK = (1 << 11),
> };
>
> /**
> --
> 2.34.1

--
~Vinod