linux-kernel - Re: [PATCH 1/4] dmaengine: qcom: bam

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Message-ID: <cf201140-9a98-88f7-d49f-d1c1cc1ae4ec@linaro.org>
Date:   Wed, 17 Jan 2018 09:46:31 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Sagar Dharia <sdharia@...eaurora.org>,
        Vinod Koul <vinod.koul@...el.com>,
        Andy Gross <andy.gross@...aro.org>, dmaengine@...r.kernel.org
Cc:     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 1/4] dmaengine: qcom: bam_dma: make bam clk optional



On 16/01/18 19:38, Sagar Dharia wrote:
> 
> On 1/16/2018 12:02 PM, srinivas.kandagatla@...aro.org wrote:
>> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>
>> When BAM is remotely controlled it does not sound correct to control
>> its clk on Linux side. Make it optional, so that its not madatory
>> for remote controlled BAM instances.
>>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>> ---
>>   drivers/dma/qcom/bam_dma.c | 15 ++++++++-------
>>   1 file changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
>> index 03c4eb3fd314..78e488e8f96d 100644
>> --- a/drivers/dma/qcom/bam_dma.c
>> +++ b/drivers/dma/qcom/bam_dma.c
>> @@ -1180,13 +1180,14 @@ static int bam_dma_probe(struct 
>> platform_device *pdev)
>>                           "qcom,controlled-remotely");
>>       bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
>> -    if (IS_ERR(bdev->bamclk))
>> -        return PTR_ERR(bdev->bamclk);
>> -
>> -    ret = clk_prepare_enable(bdev->bamclk);
>> -    if (ret) {
>> -        dev_err(bdev->dev, "failed to prepare/enable clock\n");
>> -        return ret;
>> +    if (IS_ERR(bdev->bamclk)) {
>> +        bdev->bamclk = NULL;
>> +    } else {
>> +        ret = clk_prepare_enable(bdev->bamclk);
>> +        if (ret) {
>> +            dev_err(bdev->dev, "failed to prepare/enable clock\n");
>> +            return ret;
>> +        }
> I believe you can also keep pm_runtime disabled if BAM is remotely 
> controlled.

Yes, that's another topic which should be fixed too. I will add that 
patch in next version.

thanks,
srini
> 
> Thanks
> Sagar
>>       }
>>       ret = bam_init(bdev);
>