linux-kernel - Re: [PATCH 4/6] drm/rockchip: dw_hdmi: Add vendor hdmi properties

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Message-ID: <20200813104228.096179e7@eldfell>
Date:   Thu, 13 Aug 2020 10:42:28 +0300
From:   Pekka Paalanen <ppaalanen@...il.com>
To:     crj <algea.cao@...k-chips.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        jernej.skrabec@...l.net, laurent.pinchart+renesas@...asonboard.com,
        jonas@...boo.se, airlied@...ux.ie, kuankuan.y@...il.com,
        narmstrong@...libre.com, hjc@...k-chips.com,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        a.hajda@...sung.com, tzimmermann@...e.de, jbrunet@...libre.com,
        linux-rockchip@...ts.infradead.org, darekm@...gle.com,
        sam@...nborg.org, linux-arm-kernel@...ts.infradead.org,
        cychiang@...omium.org
Subject: Re: [PATCH 4/6] drm/rockchip: dw_hdmi: Add vendor hdmi properties

On Wed, 12 Aug 2020 16:30:17 +0300
Laurent Pinchart <laurent.pinchart@...asonboard.com> wrote:

> Hi Algea,
> 
> On Wed, Aug 12, 2020 at 07:08:10PM +0800, crj wrote:
> > 在 2020/8/12 17:33, Laurent Pinchart 写道:  
> > > On Wed, Aug 12, 2020 at 04:35:43PM +0800, Algea Cao wrote:  
> > >> Introduce struct dw_hdmi_property_ops in plat_data to support
> > >> vendor hdmi property.
> > >>
> > >> Implement hdmi vendor properties color_depth_property and
> > >> hdmi_output_property to config hdmi output color depth and
> > >> color format.
> > >>
> > >> The property "hdmi_output_format", the possible value
> > >> could be:
> > >>           - RGB
> > >>           - YCBCR 444
> > >>           - YCBCR 422
> > >>           - YCBCR 420
> > >>
> > >> Default value of the property is set to 0 = RGB, so no changes if you
> > >> don't set the property.
> > >>
> > >> The property "hdmi_output_depth" possible value could be
> > >>           - Automatic
> > >>             This indicates prefer highest color depth, it is
> > >>             30bit on rockcip platform.
> > >>           - 24bit
> > >>           - 30bit
> > >> The default value of property is 24bit.
> > >>
> > >> Signed-off-by: Algea Cao <algea.cao@...k-chips.com>
> > >> ---
> > >>
> > >>   drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 174 ++++++++++++++++++++
> > >>   include/drm/bridge/dw_hdmi.h                |  22 +++
> > >>   2 files changed, 196 insertions(+)
> > >>
> > >> diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> > >> index 23de359a1dec..8f22d9a566db 100644
> > >> --- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> > >> +++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> > >> @@ -52,6 +52,27 @@
> > >>   
> > >>   #define HIWORD_UPDATE(val, mask)	(val | (mask) << 16)
> > >>   
> > >> +/* HDMI output pixel format */
> > >> +enum drm_hdmi_output_type {
> > >> +	DRM_HDMI_OUTPUT_DEFAULT_RGB, /* default RGB */
> > >> +	DRM_HDMI_OUTPUT_YCBCR444, /* YCBCR 444 */
> > >> +	DRM_HDMI_OUTPUT_YCBCR422, /* YCBCR 422 */
> > >> +	DRM_HDMI_OUTPUT_YCBCR420, /* YCBCR 420 */
> > >> +	DRM_HDMI_OUTPUT_YCBCR_HQ, /* Highest subsampled YUV */
> > >> +	DRM_HDMI_OUTPUT_YCBCR_LQ, /* Lowest subsampled YUV */
> > >> +	DRM_HDMI_OUTPUT_INVALID, /* Guess what ? */
> > >> +};  
> > >
> > > Vendor-specific properties shouldn't use names starting with drm_ or
> > > DRM_, that's for the DRM core. But this doesn't seem specific to
> > > Rockchip at all, it should be a standard property. Additionally, new
> > > properties need to come with a userspace implementation showing their
> > > usage, in X.org, Weston, the Android DRM/KMS HW composer, or another
> > > relevant upstream project (a test tool is usually not enough).  
> > 
> > We use these properties only in Android HW composer, But we can't upstream
> > 
> > our HW composer code right now.  Can we use this properties as private 
> > property
> > 
> > and do not upstream HW composer for the time being?  
> 
> It's not my decision, it's a policy of the DRM subsystem to require an
> open implementation in userspace to validate all API additions.

Also read
https://www.kernel.org/doc/html/latest/gpu/drm-uapi.html#open-source-userspace-requirements
very carefully: it calls for a FOSS userspace project's proper upstream
to have reviewed and accepted the patches to use the new UAPI, but
those patches must NOT be MERGED at that time yet.


Thanks,
pq

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