linux-kernel - Re: [PATCH 0/4] drm/atmel-hlcdc: fix plane clipping/rotation issues

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Date:   Fri, 11 Jan 2019 14:18:34 +0000
From:   <Nicolas.Ferre@...rochip.com>
To:     <bbrezillon@...nel.org>, <peda@...ntia.se>
CC:     <linux-kernel@...r.kernel.org>, <alexandre.belloni@...tlin.com>,
        <airlied@...ux.ie>, <dri-devel@...ts.freedesktop.org>,
        <boris.brezillon@...tlin.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <Joshua.Henderson@...rochip.com>
Subject: Re: [PATCH 0/4] drm/atmel-hlcdc: fix plane clipping/rotation issues

On 10/01/2019 at 18:45, Boris Brezillon wrote:
> On Thu, 10 Jan 2019 15:10:28 +0000
> Peter Rosin <peda@...ntia.se> wrote:
> 
>> Hi!
>>
>> I found an unfortunate issue while recoding plane handling to use
>> drm_atomic_helper_check_plane_state(). The driver rotates clockwise,
>> which is not correct. I simply fixed it (patch 1/4), but maybe that
>> will cause regressions for unsuspecting users who simply assumed
>> that the clockwise rotation was correct? I don't know what to do
>> about that? Adding an option to get the old broken behavior seems
>> useless, wouldn't it be just as easy to just fix whatever app to
>> rotate the other way instead of adding an option somewhere?
> 
> Hm, rotation support has been added before the standard rotation
> property was created, and at that time I assumed rotation was clockwise
> (which apparently was an unwise choice). Anyway, I don't have a
> solution for this problem, so I'll let Nicolas decide if it's
> acceptable to change the rotation behavior.

Yes, being consistent with standard DRM sub-system is far more important 
in my opinion.

Best regards,
   Nicolas

>> I have only tested this series on sama5d3, but I did check the docs
>> for various other chips (sama5d2, sama5d4, sam9n12, sam9g15, sam9g35
>> and sam9x35) supported by the driver (relevant to patch 4/4).
> 
> Thanks for addressing those problems.
> 
>>
>> Cheers,
>> Peter
>>
>> Peter Rosin (4):
>>    drm/atmel-hlcdc: rotate planes counterclockwise
>>    drm/atmel-hlcdc: do not swap w/h of the crtc when a plane is rotated
>>    drm/atmel-hlcdc: fix clipping of planes
>>    drm/atmel-hlcdc: do not immediately disable planes, wait for next
>>      frame
>>
>>   drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 179 +++++++++---------------
>>   1 file changed, 67 insertions(+), 112 deletions(-)
>>
> 
> 


-- 
Nicolas Ferre