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

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Message-ID: <64dca613-5053-46d4-9910-7ac551fdde81@quicinc.com>
Date: Thu, 26 Dec 2024 17:38:54 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Vinod Koul <vkoul@...nel.org>, Md Sadre Alam <quic_mdalam@...cinc.com>
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 12/24/2024 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...
> 
> 
>> +    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
>