Re: [PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards

Shashank


On 11/3/2016 6:56 PM, Ville Syrjälä wrote:
> On Thu, Nov 03, 2016 at 06:40:11PM +0530, Sharma, Shashank wrote:
>> Regards
>>
>> Shashank
>>
>>
>> On 11/3/2016 6:32 PM, Ville Syrjälä wrote:
>>> On Thu, Nov 03, 2016 at 12:47:39PM +0000, Sharma, Shashank wrote:
>>>> Hi Ville,
>>>> (-dri-devel)
>>>> I would appreciate an internal discussion before going to dri-devel. a
>>> Added back. Private discussions are pointless.
>> Noted.
>>>> What did this patch break ?
>>> Intel ddx. It will reject any mode with flags it doesn't know about.
>>> Other ddxen like -ati or -modesetting will also suffer, but potentially
>>> in a different way since they don't even check the flags and instead
>>> just directly stuff them into the randr mode flags, which will result
>>> in an out of spec mode as far randr is concerned.
>> Then its a fault of intel-ddx design. We are adding new flags to
>> indicate aspect ratios, so its obvious that the implementation should be
>> modified to accept new flags.
>> I dont see why you should revert patch for it.
> Rule 1 of kernel development: You simply don't break existing userspace
Again, we are adding something new, for which userspace should be modified.
If the userspace in written in such a way that it wont accept changes, 
its not saleable design.

Even in this case, we should go and extend the userspace (which I am 
ready to do) instead of reverting the patch.
If you still think you should send this revert, I am removing my NACK. 
Pls Go ahead.
>>>> This is exposed in the same way, as the 3D flags.
>>> Not it isn't. We have a client cap for 3D flags.
>>>
>>>> The information is already available in form of flags, all you have to do in userspace is read and print that. Its already being done in Android.
>>> Please stop relying on Android for testing upstream patches. Test with
>>> actual userspace people are using.
>> Please note that android goes through HDMI compliance certification, and
>> several commercial test infrastructures, so
>> that's one of the best infrastructure to test. And when we have common
>> branch for all of Linux flavors, we should consider all.
> You can test with Android as much as you like. That probably won't
> catch ABI breaks and whatnot though since you don't generally just plop
> a new kernel onto an existing Android device.
>
> So you really must test with normal userspace as well. That has a long
> history and so any ABI/behaviour change is actually a big deal.
>
>>>>    
>>>> NACK until we get to the right reason.
>>>>
>>>> Regards
>>>> Shashank
>>>> -----Original Message-----
>>>> From: ville.syrjala@linux.intel.com [mailto:ville.syrjala@linux.intel.com]
>>>> Sent: Thursday, November 3, 2016 6:02 PM
>>>> To: dri-devel@lists.freedesktop.org
>>>> Cc: Sharma, Shashank <shashank.sharma@intel.com>; Lin; Jia, Lin A <lin.a.jia@intel.com>; Sharma, Akashdeep <akashdeep.sharma@intel.com>; Jim Bride <jim.bride@linux.intel.com>; Jose Abreu <Jose.Abreu@synopsys.com>; Daniel Vetter <daniel.vetter@ffwll.ch>; Emil Velikov <emil.l.velikov@gmail.com>
>>>> Subject: [PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"
>>>>
>>>> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>>
>>>> This reverts commit a68362fe3e84fcbedd49939aa200519aa5410135.
>>>>
>>>> Adding new mode flags willy nilly breaks existing userspace. We need to coordinate this better, potentially with a new client cap that only exposes the aspect ratio flags when userspace is prepared for them (similar to what we do with stereo 3D modes).
>>>>
>>>> Cc: Shashank Sharma <shashank.sharma@intel.com>
>>>> Cc: Lin, Jia <lin.a.jia@intel.com>
>>>> Cc: Akashdeep Sharma <akashdeep.sharma@intel.com>
>>>> Cc: Jim Bride <jim.bride@linux.intel.com>
>>>> Cc: Jose Abreu <Jose.Abreu@synopsys.com>
>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>> Cc: Emil Velikov <emil.l.velikov@gmail.com>
>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>> ---
>>>>    drivers/gpu/drm/drm_modes.c | 12 ------------  include/uapi/drm/drm_mode.h |  6 ------
>>>>    2 files changed, 18 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c index f64ac86deb84..725faa6409aa 100644
>>>> --- a/drivers/gpu/drm/drm_modes.c
>>>> +++ b/drivers/gpu/drm/drm_modes.c
>>>> @@ -1513,12 +1513,6 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out,
>>>>    	case HDMI_PICTURE_ASPECT_16_9:
>>>>    		out->flags |= DRM_MODE_FLAG_PIC_AR_16_9;
>>>>    		break;
>>>> -	case HDMI_PICTURE_ASPECT_64_27:
>>>> -		out->flags |= DRM_MODE_FLAG_PIC_AR_64_27;
>>>> -		break;
>>>> -	case DRM_MODE_PICTURE_ASPECT_256_135:
>>>> -		out->flags |= DRM_MODE_FLAG_PIC_AR_256_135;
>>>> -		break;
>>>>    	case HDMI_PICTURE_ASPECT_RESERVED:
>>>>    	default:
>>>>    		out->flags |= DRM_MODE_FLAG_PIC_AR_NONE; @@ -1580,12 +1574,6 @@ int drm_mode_convert_umode(struct drm_display_mode *out,
>>>>    	case DRM_MODE_FLAG_PIC_AR_16_9:
>>>>    		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_16_9;
>>>>    		break;
>>>> -	case DRM_MODE_FLAG_PIC_AR_64_27:
>>>> -		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_64_27;
>>>> -		break;
>>>> -	case DRM_MODE_FLAG_PIC_AR_256_135:
>>>> -		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_256_135;
>>>> -		break;
>>>>    	default:
>>>>    		out->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
>>>>    		break;
>>>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h index 084b50a02dc5..5c142b1387ac 100644
>>>> --- a/include/uapi/drm/drm_mode.h
>>>> +++ b/include/uapi/drm/drm_mode.h
>>>> @@ -81,8 +81,6 @@ extern "C" {
>>>>    #define DRM_MODE_PICTURE_ASPECT_NONE		0
>>>>    #define DRM_MODE_PICTURE_ASPECT_4_3		1
>>>>    #define DRM_MODE_PICTURE_ASPECT_16_9		2
>>>> -#define DRM_MODE_PICTURE_ASPECT_64_27		3
>>>> -#define DRM_MODE_PICTURE_ASPECT_256_135		4
>>>>    
>>>>    /* Aspect ratio flag bitmask (4 bits 22:19) */
>>>>    #define DRM_MODE_FLAG_PIC_AR_MASK		(0x0F<<19)
>>>> @@ -92,10 +90,6 @@ extern "C" {
>>>>    			(DRM_MODE_PICTURE_ASPECT_4_3<<19)
>>>>    #define  DRM_MODE_FLAG_PIC_AR_16_9 \
>>>>    			(DRM_MODE_PICTURE_ASPECT_16_9<<19)
>>>> -#define  DRM_MODE_FLAG_PIC_AR_64_27 \
>>>> -			(DRM_MODE_PICTURE_ASPECT_64_27<<19)
>>>> -#define  DRM_MODE_FLAG_PIC_AR_256_135 \
>>>> -			(DRM_MODE_PICTURE_ASPECT_256_135<<19)
>>>>    
>>>>    /* DPMS flags */
>>>>    /* bit compatible with the xorg definitions. */
>>>> --
>>>> 2.7.4
>>>>

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