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Subject: Re: [PATCH 08/28] venus: hfi_venus: add suspend function for 4xx
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To:     Vikash Garodia <vgarodia@codeaurora.org>,
        Stanimir Varbanov <stanimir.varbanov@linaro.org>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-media-owner@vger.kernel.org
References: <20180424124436.26955-1-stanimir.varbanov@linaro.org>
 <20180424124436.26955-9-stanimir.varbanov@linaro.org>
 <8f26cd748f283043b32da05b39f29348@codeaurora.org>
 <ce03189a-b56e-e73e-852f-1ad10d4c8bd3@linaro.org>
 <4bb351351a9725db42bf06da1e778290@codeaurora.org>
From:   Stanimir Varbanov <stanimir.varbanov@linaro.org>
Message-ID: <9f46bca2-4e86-bafc-198d-c7d2f001fbe6@linaro.org>
Date:   Wed, 9 May 2018 17:26:16 +0300
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Hi,

On 05/09/2018 05:14 PM, Vikash Garodia wrote:
> Hi Stanimir,
> 
> On 2018-05-09 16:45, Stanimir Varbanov wrote:
>> Hi Vikash,
>>
>> On 05/02/2018 09:07 AM, vgarodia@codeaurora.org wrote:
>>> Hello Stanimir,
>>>
>>> On 2018-04-24 18:14, Stanimir Varbanov wrote:
>>>> This adds suspend (power collapse) function with slightly
>>>> different order of calls comparing with Venus 3xx.
>>>>
>>>> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
>>>> ---
>>>>  drivers/media/platform/qcom/venus/hfi_venus.c | 52
>>>> +++++++++++++++++++++++++++
>>>>  1 file changed, 52 insertions(+)
>>>>
>>>> diff --git a/drivers/media/platform/qcom/venus/hfi_venus.c
>>>> b/drivers/media/platform/qcom/venus/hfi_venus.c
>>>> index 53546174aab8..f61d34bf61b4 100644
>>>> --- a/drivers/media/platform/qcom/venus/hfi_venus.c
>>>> +++ b/drivers/media/platform/qcom/venus/hfi_venus.c
>>>> @@ -1443,6 +1443,55 @@ static int venus_suspend_1xx(struct venus_core
>>>> *core)
>>>>      return 0;
>>>>  }
>>>>
>>>> +static int venus_suspend_4xx(struct venus_core *core)
>>>> +{
>>>> +    struct venus_hfi_device *hdev = to_hfi_priv(core);
>>>> +    struct device *dev = core->dev;
>>>> +    u32 val;
>>>> +    int ret;
>>>> +
>>>> +    if (!hdev->power_enabled || hdev->suspended)
>>>> +        return 0;
>>>> +
>>>> +    mutex_lock(&hdev->lock);
>>>> +    ret = venus_is_valid_state(hdev);
>>>> +    mutex_unlock(&hdev->lock);
>>>> +
>>>> +    if (!ret) {
>>>> +        dev_err(dev, "bad state, cannot suspend\n");
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    ret = venus_prepare_power_collapse(hdev, false);
>>>> +    if (ret) {
>>>> +        dev_err(dev, "prepare for power collapse fail (%d)\n", ret);
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    ret = readl_poll_timeout(core->base + CPU_CS_SCIACMDARG0, val,
>>>> +                 val & CPU_CS_SCIACMDARG0_PC_READY,
>>>> +                 POLL_INTERVAL_US, 100000);
>>>> +    if (ret) {
>>>> +        dev_err(dev, "Polling power collapse ready timed out\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    mutex_lock(&hdev->lock);
>>>> +
>>>> +    ret = venus_power_off(hdev);
>>>> +    if (ret) {
>>>> +        dev_err(dev, "venus_power_off (%d)\n", ret);
>>>> +        mutex_unlock(&hdev->lock);
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    hdev->suspended = true;
>>>> +
>>>> +    mutex_unlock(&hdev->lock);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>>  static int venus_suspend_3xx(struct venus_core *core)
>>>>  {
>>>>      struct venus_hfi_device *hdev = to_hfi_priv(core);
>>>> @@ -1507,6 +1556,9 @@ static int venus_suspend(struct venus_core *core)
>>>>      if (core->res->hfi_version == HFI_VERSION_3XX)
>>>>          return venus_suspend_3xx(core);
>>>>
>>>> +    if (core->res->hfi_version == HFI_VERSION_4XX)
>>>> +        return venus_suspend_4xx(core);
>>>> +
>>>>      return venus_suspend_1xx(core);
>>>>  }
>>>
>>> Let me brief on the power collapse sequence for Venus_4xx
>>> 1. Host checks for ARM9 and Video core to be idle.
>>>    This can be done by checking for WFI bit (bit 0) in CPU status
>>> register for ARM9 and by checking bit 30 in Control status reg for video
>>> core/s.
>>> 2. Host then sends command to ARM9 to prepare for power collapse.
>>> 3. Host then checks for WFI bit and PC_READY bit before withdrawing
>>> going for power off.
>>>
>>> As per this patch, host is preparing for power collapse without checking
>>> for #1.
>>> Update the code to handle #3.
>>
>> This looks similar to suspend for Venus 3xx. Can you confirm that the
>> sequence of checks for 4xx is the same as 3xx?
> 
> Do you mean the driver implementation for Suspend Venus 3xx or the hardware
> expectation for Venus 3xx ? If hardware expectation wise, the sequence is
> same for 3xx and 4xx.
> In the suspend implementation for 3xx, i see that the host just reads
> the WFI
> and idle status bits, but does not validate those bit value before
> preparing
> Venus for power collapse. Sequence #2 and #3 is followed for Venus 3xx
> implementation.

OK, than we can reuse venus_suspend_3xx function for 4xx, just need to
fix WFI and idle bit for #1.

-- 
regards,
Stan