Re: [PATCH 1/2] drm: Stop using drm_vblank_count() as the hw frame counter

[Vincent ABRIOU <vincent.abriou@st.com>]

On 09/30/2015 04:14 PM, Ville Syrjälä wrote:
> On Wed, Sep 30, 2015 at 04:08:02PM +0200, Daniel Vetter wrote:
>> On Wed, Sep 30, 2015 at 04:46:48PM +0300, ville.syrjala@linux.intel.com wrote:
>>> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>
>>> drm_vblank_count() returns the software counter. We should not pretend
>>> it's the hw counter since we use the hw counter to figuere out what the
>>> software counter value should be. So instead provide a new function
>>> drm_vblank_no_hw_counter() for drivers that don't have a real hw
>>> counter. The new function simply returns 0, which is about the only
>>> thing it can do.
>>
>> Shouldn't we instead just make the get_vblank_counter hook optional?
>
> Perhaps. But maybe this way would encourage people to go look for a
> hw frame counter in their hardware?
>
>> -Daniel
>>
>>>
>>> Cc: Vincent Abriou <vincent.abriou@st.com>
>>> Cc: Thierry Reding <treding@nvidia.com>
>>> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>> ---
>>>   drivers/gpu/drm/armada/armada_drv.c          |  2 +-
>>>   drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c |  2 +-
>>>   drivers/gpu/drm/drm_irq.c                    | 17 +++++++++++++++++
>>>   drivers/gpu/drm/exynos/exynos_drm_drv.c      |  2 +-
>>>   drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c    |  2 +-
>>>   drivers/gpu/drm/imx/imx-drm-core.c           |  2 +-

[..]

>>> --- a/drivers/gpu/drm/drm_irq.c
>>> +++ b/drivers/gpu/drm/drm_irq.c
>>> @@ -1797,3 +1797,20 @@ bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
>>>      return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
>>>   }
>>>   EXPORT_SYMBOL(drm_crtc_handle_vblank);
>>> +
>>> +/**
>>> + * drm_vblank_no_hw_counter - "No hw counter" implementation of .get_vblank_counter()
>>> + * @dev: DRM device
>>> + * @pipe: CRTC for which to read the counter
>>> + *
>>> + * Drivers can plug this into the .get_vblank_counter() function if
>>> + * there is no useable hardware frame counter available.
>>> + *
>>> + * Returns:
>>> + * 0
>>> + */
>>> +u32 drm_vblank_no_hw_counter(struct drm_device *dev, int pipe)

warning when building the kernel:
int pipe => unsigned int pipe

BR
Vincent
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