On 04/08/2014 10:08 AM, Denis Carikli wrote:
> On 04/08/2014 08:36 AM, Andrzej Hajda wrote:
>>
>> Hi Denis,
> Hi,
>
>>> +#define DRM_MODE_FLAG_POL_PIXDATA_NEGEDGE BIT(1)
>>> +#define DRM_MODE_FLAG_POL_PIXDATA_POSEDGE BIT(2)
>>> +#define DRM_MODE_FLAG_POL_PIXDATA_PRESERVE BIT(3)
>>
>> What is the purpose of DRM_MODE_FLAG_POL_PIXDATA_PRESERVE?
>> If 'preserve' means 'ignore' we can set to zero negedge and posedge bits
>> instead of adding new bit. If it is something different please describe it.
> Yes, it meant 'ignore'.
>
> The goal was to be able to have a way to keep the old behavior while
> still being able to set the flags.
>
> So, with the imx-drm driver, if none of the DRM_MODE_FLAG_POL_PIXDATA
> were set(that is POSEDGE, NEGEDGE, PRESERVE), then in ipuv3-crtc.c, it
> went using the old flags settings that were previously hardcoded.
>
> The same applied for DRM_MODE_FLAG_POL_DE.
> The patch using theses flags is the 08/12 of this same serie.
So as I understand you want to:
- do not change hw polarity settings by using preserve bit,
- keep the old behavior of the driver by setting all bits to zero.
I think this is the issue of the specific driver, and it should not
influence core structs.
I am not familiar with imx but I guess it should not be a problem
to solve the issue in the driver.
>
>>> struct drm_display_mode {
> [..]
>>> + unsigned int pol_flags;
>>
>> Adding field and macros description to the DocBook would be nice.
> So I will have to describe it in the "Connector Helper Operations"
> section of drm.tmpl, right before the mode_valid synopsis ?
Yes, I think so.
Andrzej
>
> Denis.
>
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