linux-kernel - Re: [PATCH v13 1/2] drivers/coresight: Add UltraSoc System Memory Buffer driver

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Date:   Wed, 23 Nov 2022 14:54:27 +0800
From:   hejunhao <hejunhao3@...wei.com>
To:     Suzuki K Poulose <suzuki.poulose@....com>,
        <mathieu.poirier@...aro.org>, <mike.leach@...aro.org>,
        <leo.yan@...aro.org>, <jonathan.cameron@...wei.com>,
        <john.garry@...wei.com>
CC:     <coresight@...ts.linaro.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-doc@...r.kernel.org>, <lpieralisi@...nel.org>,
        <linuxarm@...wei.com>, <yangyicong@...wei.com>,
        <liuqi115@...wei.com>, <f.fangjian@...wei.com>,
        <prime.zeng@...ilicon.com>
Subject: Re: [PATCH v13 1/2] drivers/coresight: Add UltraSoc System Memory
 Buffer driver

Hi Suzuki ,

On 2022/11/22 22:06, Suzuki K Poulose wrote:
> On 22/11/2022 13:23, hejunhao wrote:
>>
>> On 2022/11/21 18:47, Suzuki Kuruppassery Poulose wrote:
>>> On 18/11/2022 12:45, hejunhao wrote:
>>>> Hi Suzuki ,
>>>>
>>>>
>>>> On 2022/11/15 19:06, Suzuki K Poulose wrote:
>>>>> On 14/11/2022 09:03, Junhao He wrote:
>>>>>> From: Qi Liu <liuqi115@...wei.com>
>>>>>>
>>>
>>>>>> +static void smb_init_hw(struct smb_drv_data *drvdata)
>>>>>> +{
>>>>>> +    /* First disable SMB and clear the status of SMB buffer */
>>>>>> +    smb_reset_buffer_status(drvdata);
>>>>>> +    smb_disable_hw(drvdata);
>>>>>> +    smb_purge_data(drvdata);
>>>>>> +
>>>>>> +    writel(SMB_LB_CFG_LO_DEFAULT, drvdata->base + 
>>>>>> SMB_LB_CFG_LO_REG);
>>>>>> +    writel(SMB_LB_CFG_HI_DEFAULT, drvdata->base + 
>>>>>> SMB_LB_CFG_HI_REG);
>>>>>> +    writel(SMB_GLB_CFG_DEFAULT, drvdata->base + SMB_GLB_CFG_REG);
>>>>>> +    writel(SMB_GLB_INT_CFG, drvdata->base + SMB_GLB_INT_REG);
>>>>>> +    writel(SMB_LB_INT_CTRL_CFG, drvdata->base + 
>>>>>> SMB_LB_INT_CTRL_REG);
>>>>>
>>>>> Does this come with interrupt on overflow ? Do we not use this ?
>>>>>
>>>> When the buffer overflow, no interrupt will come.
>>>> Interrupt will upgrade SMB_LB_INT_STS_REG register status if start 
>>>> trace.
>>>> Thanks.
>>>>> Rest looks fine to me.
>>>
>>> What is the purpose of the "Interrupt" on the SMB ? It is not clear to
>>> me.
>> The SMB_LB_INT_CTRL_REG register control the validity of both real-time
>> events and interrupts. When logical buffer status changes causes to 
>> issue an
>> interrupt at the same time as it issues a real-time event.
>> Real-time events are used in SMB driver, which needs to get the 
>> buffer status.
>> Interrupts are used in debugger mode and cannot be registered in kernel.
>>   ..._BUF_NOTE_MASK control which events flags or interrupts are valid.
>
> Please add this to a comment in the code above the register write.
>
> Thanks
> Suzuki
>
Yes, thanks for the comment. I will do that.

Best regards,
Junhao.
>>
>> Thanks.
>>
>> Best regards,
>> Junhao.
>>
>>> Suzuki
>>>
>>> _______________________________________________
>>> CoreSight mailing list -- coresight@...ts.linaro.org
>>> To unsubscribe send an email to coresight-leave@...ts.linaro.org
>>
>
> _______________________________________________
> CoreSight mailing list -- coresight@...ts.linaro.org
> To unsubscribe send an email to coresight-leave@...ts.linaro.org