Re: [PATCH v6 02/12] dmaengine: add DMA_PREP_LOCK and DMA_PREP_UNLOCK flag

[Md Sadre Alam <quic_mdalam@xxxxxxxxxxx>]

On 3/11/2025 2:06 AM, Vinod Koul wrote:
> On 15-01-25, 15:59, 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.
>
> Have you aligned internally b/w team at Qualcomm to have this as single
> approach for LOCK implementation. I would like to see ack from
> Mukesh/Bjorn before proceeding ahead with this
I have already discuss this internally with Mukesh and he has posted his 
response here [1]
[1] 
https://lore.kernel.org/all/1566eafb-7286-4f27-922d-0bbaaab8120b@xxxxxxxxxxx/
> > Signed-off-by: Md Sadre Alam <quic_mdalam@xxxxxxxxxxx>
> > ---
> >
> > Change in [v6]
> >
> > * Change "BAM" to "DAM"
> >
> > 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..a032e55d0a4f 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 DMA will lock all other pipes not related to the current
> > +    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, DMA 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