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Subject: Re: [PATCH 0/6] Refactor the vkms to accept new formats
To:     Pekka Paalanen <ppaalanen@gmail.com>
Cc:     rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com,
        hamohammed.sa@gmail.com, daniel@ffwll.ch, airlied@linux.ie,
        contact@emersion.fr, leandro.ribeiro@collabora.com,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        lkcamp@lists.libreplanetbr.org
References: <20211005201637.58563-1-igormtorrente@gmail.com>
 <20211018105333.5f1bf9fe@eldfell>
From:   Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
Message-ID: <2202889c-b865-124f-1035-35fd66d10a0c@gmail.com>
Date:   Mon, 18 Oct 2021 15:05:56 -0300
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Hi pq,

On 10/18/21 4:53 AM, Pekka Paalanen wrote:
> On Tue,  5 Oct 2021 17:16:31 -0300
> Igor Matheus Andrade Torrente <igormtorrente@gmail.com> wrote:
> 
>> XRGB to ARGB behavior
>> =================
>> During the development, I decided to always fill the alpha channel of
>> the output pixel whenever the conversion from a format without an alpha
>> channel to ARGB16161616 is necessary. Therefore, I ignore the value
>> received from the XRGB and overwrite the value with 0xFFFF.
>>
>> My question is, is this behavior acceptable?
> 
> Hi,
> 
> that is the expected behaviour. X channel values must never affect
> anything on screen, hence they must never affect other channels'
> values. You are free to completely ignore X channel values, and if your
> output buffer has X channel, then you are free to write (or not write,
> unless for security reasons) whatever into it.
> 

Great!! And thanks!!!

> 
> Thanks,
> pq
> 
>>
>> [1] https://lists.freedesktop.org/archives/igt-dev/2021-October/036125.html
>>
>> Igor Matheus Andrade Torrente (6):
>>    drm: vkms: Replace the deprecated drm_mode_config_init
>>    drm: vkms: Alloc the compose frame using vzalloc
>>    drm: vkms: Replace hardcoded value of `vkms_composer.map` to
>>      DRM_FORMAT_MAX_PLANES
>>    drm: vkms: Add fb information to `vkms_writeback_job`
>>    drm: vkms: Prepare `vkms_wb_encoder_atomic_check` to accept multiple
>>      formats
>>    drm: vkms: Refactor the plane composer to accept new formats
>>
>>   drivers/gpu/drm/vkms/vkms_composer.c  | 275 ++++++++++++++------------
>>   drivers/gpu/drm/vkms/vkms_drv.c       |   5 +-
>>   drivers/gpu/drm/vkms/vkms_drv.h       |  12 +-
>>   drivers/gpu/drm/vkms/vkms_formats.h   | 125 ++++++++++++
>>   drivers/gpu/drm/vkms/vkms_writeback.c |  27 ++-
>>   5 files changed, 304 insertions(+), 140 deletions(-)
>>   create mode 100644 drivers/gpu/drm/vkms/vkms_formats.h
>>
>