linux-kernel - Re: [PATCH 0/4] dmaengine: qcom: bam_dma: fixes for remotely controlled bam

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Date:   Wed, 17 Jan 2018 10:55:34 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Vinod Koul <vinod.koul@...el.com>
Cc:     Andy Gross <andy.gross@...aro.org>, dmaengine@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Brown <david.brown@...aro.org>,
        Dan Williams <dan.j.williams@...el.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        yanhe@...cinc.com, ramkri@....qualcomm.com, sdharia@...cinc.com
Subject: Re: [PATCH 0/4] dmaengine: qcom: bam_dma: fixes for remotely
 controlled bam



On 17/01/18 10:18, Vinod Koul wrote:
> On Tue, Jan 16, 2018 at 07:02:32PM +0000, srinivas.kandagatla@...aro.org wrote:
>> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>
>> Hi Andy,
>>
>> I did hit few issues while trying out SLIMBus BAM on DB820c, this BAM instance
>> is remotely controlled and powered up after ADSP is booted using QMI commands.
> 
> What do you mean by "remotely controlled" in this series?

DMA controller is controlled by the remote processor, which is a DSP in 
this case.
Linux side is in remote mode in this setup, this can setup transfer 
descriptors and start/stop a transfer. But all the 
initialization/powerup part will be done in the remote processor.

--srini

> 
>>
>> Firstly some of the master registers are written even when the BAM is remotely
>> controlled, and secondly reading registers when bam is not ready yet.
>>
>> These 4 patches address these issues, there are few more issues like doing PM
>> in simillar usecase, these will be addressed soon.
>>
>> Thanks,
>> Srini
>>
>> Srinivas Kandagatla (4):
>>    dmaengine: qcom: bam_dma: make bam clk optional
>>    dmaengine: qcom: bam_dma: add num-channels binding for remotely
>>      controlled
>>    dmaengine: qcom: bam_dma: do not write to global regs in remote mode
>>    dmaengine: qcom: bam_dma: Add num-ees dt binding for remotely
>>      controlled
>>
>>   .../devicetree/bindings/dma/qcom_bam_dma.txt       |  4 ++
>>   drivers/dma/qcom/bam_dma.c                         | 56 +++++++++++++++-------
>>   2 files changed, 43 insertions(+), 17 deletions(-)
>>
>> -- 
>> 2.15.1
>>
>