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Subject: Re: [PATCH v13 1/2] drivers/coresight: Add UltraSoc System Memory
 Buffer driver
To:     Suzuki Kuruppassery Poulose <suzuki.poulose@arm.com>,
        <mathieu.poirier@linaro.org>, <mike.leach@linaro.org>,
        <leo.yan@linaro.org>, <jonathan.cameron@huawei.com>,
        <john.garry@huawei.com>
References: <20221114090316.63157-1-hejunhao3@huawei.com>
 <20221114090316.63157-2-hejunhao3@huawei.com>
 <92291cb2-859c-a994-b05d-806def431376@arm.com>
 <c07e6417-7a37-3cf5-d3dd-b3ce7b3c20b1@huawei.com>
 <1c8da30c-d798-729d-c8e5-73a07f8b9f18@arm.com>
CC:     <coresight@lists.linaro.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-doc@vger.kernel.org>, <lpieralisi@kernel.org>,
        <linuxarm@huawei.com>, <yangyicong@huawei.com>,
        <liuqi115@huawei.com>, <f.fangjian@huawei.com>,
        <prime.zeng@hisilicon.com>
From:   hejunhao <hejunhao3@huawei.com>
Message-ID: <95024107-94d2-6114-4c50-b152c4da362b@huawei.com>
Date:   Tue, 22 Nov 2022 21:23:44 +0800
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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@huawei.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.

Thanks.

Best regards,
Junhao.

> Suzuki
>
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