linux-kernel - Re: [PATCH v5 02/12] dmaengine: add DMA_PREP_LOCK and DMA_PREP

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Message-ID: <872a4b2e-26e8-1c53-72aa-9fdd02069280@quicinc.com>
Date: Wed, 15 Jan 2025 11:01:26 +0530
From: Md Sadre Alam <quic_mdalam@...cinc.com>
To: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>,
        Vinod Koul
	<vkoul@...nel.org>
CC: <corbet@....net>, <thara.gopinath@...il.com>,
        <herbert@...dor.apana.org.au>, <davem@...emloft.net>,
        <kees@...nel.org>, <dave.jiang@...el.com>, <dmaengine@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-crypto@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <quic_srichara@...cinc.com>, <quic_varada@...cinc.com>,
        <quic_utiwari@...cinc.com>
Subject: Re: [PATCH v5 02/12] dmaengine: add DMA_PREP_LOCK and DMA_PREP_UNLOCK
 flag



On 12/26/2024 5:38 PM, Mukesh Kumar Savaliya wrote:
> 
> 
> On 12/24/2024 4:04 PM, Vinod Koul wrote:
>> 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@...cinc.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
>>
> Yes, should be DAM to be generic.
>> Anyone can use this new method and not just BAM...
Will change this in next revision.
>>
>>
>>> +    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
>>
>