[PATCH] drm/msm/mdp5: fix reading hw revision on db410c platform

[Abhinav Kumar]

On 11/25/2022 1:21 AM, Dmitry Baryshkov wrote:
> On 25/11/2022 07:45, Abhinav Kumar wrote:
>> On 11/24/2022 4:02 PM, Dmitry Baryshkov wrote:
>>> Since the commit commit c6122688f265 ("drm/msm/mdp5: stop overriding
>>> drvdata") reading the MDP5 hw revision on db410c will crash the board
>>> as the MDSS_GDSC is not enabled. Revert a part of the offending commit
>>> (moving rpm enablement) and set priv->kms earlier. This make it possible
>>> to use pm_runtime_get_sync() during read_mdp_hw_revision(), which will
>>> power up both the MDP5 and MDSS devices.
>>>
>>
>> This is the exact concern I had even when c6122688f265 was pushed.
>>
>> https://patchwork.freedesktop.org/patch/508334/#comment_917689
>>
>> Was the response given that time not correct then?
> 
> Not fully correct. I did not notice, that non-rpm-enabled mdp5 node 
> doesn't force mdss to be in the on state. (Which is strange. Maybe we 
> are leaking pm_runtime_enable() for it somewhere.)
> 

hmmm, this is a safer change as we are atleast not bypassing pm runtime.

 From that perspective,

Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>
>> https://patchwork.freedesktop.org/patch/508334/#comment_917713
>>> Fixes: c6122688f265 ("drm/msm/mdp5: stop overriding drvdata")
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> ---
>>>   drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 17 ++++++++---------
>>>   1 file changed, 8 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c 
>>> b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> index b46f983f2b46..29ae5c9613f3 100644
>>> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> @@ -519,10 +519,9 @@ static void read_mdp_hw_revision(struct mdp5_kms 
>>> *mdp5_kms,
>>>       struct device *dev = &mdp5_kms->pdev->dev;
>>>       u32 version;
>>> -    /* Manually enable the MDP5, as pm runtime isn't usable yet. */
>>> -    mdp5_enable(mdp5_kms);
>>> +    pm_runtime_get_sync(dev);
>>>       version = mdp5_read(mdp5_kms, REG_MDP5_HW_VERSION);
>>> -    mdp5_disable(mdp5_kms);
>>> +    pm_runtime_put_sync(dev);
>>>       *major = FIELD(version, MDP5_HW_VERSION_MAJOR);
>>>       *minor = FIELD(version, MDP5_HW_VERSION_MINOR);
>>> @@ -839,6 +838,12 @@ static int mdp5_init(struct platform_device 
>>> *pdev, struct drm_device *dev)
>>>        */
>>>       clk_set_rate(mdp5_kms->core_clk, 200000000);
>>> +    /* set uninit-ed kms */
>>> +    priv->kms = &mdp5_kms->base.base;
>>> +
>>> +    pm_runtime_enable(&pdev->dev);
>>> +    mdp5_kms->rpm_enabled = true;
>>> +
>>>       read_mdp_hw_revision(mdp5_kms, &major, &minor);
>>>       mdp5_kms->cfg = mdp5_cfg_init(mdp5_kms, major, minor);
>>> @@ -887,12 +892,6 @@ static int mdp5_init(struct platform_device 
>>> *pdev, struct drm_device *dev)
>>>       if (ret)
>>>           goto fail;
>>> -    /* set uninit-ed kms */
>>> -    priv->kms = &mdp5_kms->base.base;
>>> -
>>> -    pm_runtime_enable(&pdev->dev);
>>> -    mdp5_kms->rpm_enabled = true;
>>> -
>>>       return 0;
>>>   fail:
>>>       if (mdp5_kms)
>