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protocol="application/pgp-signature"; micalg=pgp-sha256 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - whm50.louhi.net X-AntiAbuse: Original Domain - lists.infradead.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - haloniitty.fi X-Get-Message-Sender-Via: whm50.louhi.net: authenticated_id: pekka.paalanen@haloniitty.fi X-Authenticated-Sender: whm50.louhi.net: pekka.paalanen@haloniitty.fi X-Source: X-Source-Args: X-Source-Dir: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250327_022056_101209_39AA0134 X-CRM114-Status: GOOD ( 18.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --Sig_/7H.ebBBVZVPLEOgRm0td_vf Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 26 Mar 2025 15:55:18 +0200 Tomi Valkeinen wrote: > Hi, >=20 > On 26/03/2025 15:52, Geert Uytterhoeven wrote: > > Hi Tomi, > >=20 > > On Wed, 26 Mar 2025 at 14:23, Tomi Valkeinen > > wrote: =20 > >> Add greyscale Y8 format. > >> > >> Acked-by: Dmitry Baryshkov > >> Signed-off-by: Tomi Valkeinen =20 > >=20 > > Thanks for your patch! > > =20 > >> --- a/include/uapi/drm/drm_fourcc.h > >> +++ b/include/uapi/drm/drm_fourcc.h > >> @@ -405,6 +405,9 @@ extern "C" { > >> #define DRM_FORMAT_YUV444 fourcc_code('Y', 'U', '2', '4') /* no= n-subsampled Cb (1) and Cr (2) planes */ > >> #define DRM_FORMAT_YVU444 fourcc_code('Y', 'V', '2', '4') /* no= n-subsampled Cr (1) and Cb (2) planes */ > >> > >> +/* Greyscale formats */ > >> + > >> +#define DRM_FORMAT_Y8 fourcc_code('G', 'R', 'E', 'Y') /* 8-= bit Y-only */ =20 > >=20 > > This format differs from e.g. DRM_FORMAT_R8, which encodes > > the number of bits in the FOURCC format. What do you envision > > for e.g. DRM_FORMAT_Y16? fourcc_code('G', 'R', '1', '6')? =20 >=20 > I wanted to use the same fourcc as on V4L2 side. Strictly speaking it's=20 > not required, but different fourccs for the same formats do confuse. >=20 > So, generally speaking, I'd pick an existing fourcc from v4l2 side if=20 > possible, and if not, invent a new one. Hi Tomi, what's the actual difference between DRM_FORMAT_R8 and DRM_FORMAT_Y8? Is the difference that when R8 gets expanded to RGB, it becomes (R, 0, 0), but Y8 gets expanded to (c1 * Y, c2 * Y, c3 * Y) where c1..c3 are defined by MatrixCoefficients (H.273 terminology)? That would be my intuitive assumption following how YCbCr is handled. Is it obvious enough, or should there be a comment to that effect? 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