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

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Message-ID: <2f65e490-c264-9771-b120-e5ce76376170@arm.com>
Date:   Tue, 22 Nov 2022 14:06:23 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     hejunhao <hejunhao3@...wei.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

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

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