linux-kernel - Re: [PATCH 08/28] venus: hfi_venus: add suspend function for 4xx version

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Date:   Wed, 09 May 2018 19:44:41 +0530
From:   Vikash Garodia <vgarodia@...eaurora.org>
To:     Stanimir Varbanov <stanimir.varbanov@...aro.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-media-owner@...r.kernel.org
Subject: Re: [PATCH 08/28] venus: hfi_venus: add suspend function for 4xx
 version

Hi Stanimir,

On 2018-05-09 16:45, Stanimir Varbanov wrote:
> Hi Vikash,
> 
> On 05/02/2018 09:07 AM, vgarodia@...eaurora.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@...aro.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.