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[83.233.6.197]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-54e903aa6dcsm1141164e87.236.2025.04.28.23.15.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Apr 2025 23:15:47 -0700 (PDT) Date: Tue, 29 Apr 2025 08:15:44 +0200 From: Marcus Folkesson To: Geert Uytterhoeven Cc: David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Zimmermann , Javier Martinez Canillas Subject: Re: [PATCH v6 2/3] drm/st7571-i2c: add support for Sitronix ST7571 LCD controller Message-ID: References: <20250423-st7571-v6-0-e9519e3c4ec4@gmail.com> <20250423-st7571-v6-2-e9519e3c4ec4@gmail.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="QDuqjw5mtcb8cj4X" Content-Disposition: inline In-Reply-To: --QDuqjw5mtcb8cj4X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello Geert, On Thu, Apr 24, 2025 at 10:38:33AM +0200, Geert Uytterhoeven wrote: [...] > > + /* > > + * As the display supports grayscale, all pixel= s must be written as two bits > > + * even if the format is monochrome. > > + * > > + * The bit values maps to the following graysca= le: > > + * 0 0 =3D White > > + * 0 1 =3D Light gray > > + * 1 0 =3D Dark gray > > + * 1 1 =3D Black >=20 > That is not R2, but D2? > include/uapi/drm/drm_fourcc.h: >=20 > /* 2 bpp Red (direct relationship between channel value and brightnes= s) */ > #define DRM_FORMAT_R2 fourcc_code('R', '2', ' ', ' ') > /* [7:0] R0:R1:R2:R3 2:2:2:2 four pixels/byte */ >=20 > /* 2 bpp Darkness (inverse relationship between channel value and > brightness) */ > #define DRM_FORMAT_D2 fourcc_code('D', '2', ' ', ' ') > /* [7:0] D0:D1:D2:D3 2:2:2:2 four pixels/byte */ >=20 > So the driver actually supports D1 and D2, and XRGB8888 should be > inverted while converting to monochrome (and grayscale, which is not > yet implemented). The display supports "reverse" grayscale, so the mapping becomes 1 1 =3D White 1 0 =3D Light gray 0 1 =3D Dark gray 0 0 =3D Black instead. So I will probably add support for D1 and D2 formats and invert the pixels for the R1, R2 and XRGB8888 formats. Could that work or are there any side effects that I should be aware of? Best regards, Marcus Folkesson --QDuqjw5mtcb8cj4X Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEBVGi6LZstU1kwSxliIBOb1ldUjIFAmgQbosACgkQiIBOb1ld UjJ8hBAA0PylSTjAVScRP2Rlx1rrCav8iBWJi/3/qrUdk0pKJiMyibtLJkx8M6VK 1CgpOTPMOdMvoeoBdqqQfUMdQX2V3uW6NUHSJizQEVuUPIRklwahRg3jI0BlnE1o QVcSCbBr527o9jItXC0B0bNlBmKUbqa1v0jKaAtH/+ZU7KsTjr+jI7HVvUdHwcpP gSdpWn5f+hw3GnlAP9JzGvDddPmniwjTNxJbaUEqxWsQCidsHLNicSne4kFCifZ6 5JVZki7KIkIjW2czWyZxmlBUqvVZX5Yxskmgdq4pjZ8MwAL8xtT2zorZmwIJJtGc MoRTcPPuMMzIAhwUQow6DWTx+AAwVadn+1wdsnEHHJzBVTRsiWn3K0pMciCDQF4C mr641j8DNfMBK8bzOT87T6gu9BNn4abR7asSG1n8L3Cvil0xQRXmZ1tgD6s6cxBy 2e1LzVekrwwLQy2Zo8jxFxwvBApLDLDeXnfxyhJj9hDUvqIzQzp0YAk29JiIJsoh Eer3TWAvq6bpWA014nyidG2I87zejonG1W4zL67Je4toNjSmmraz5msX9vLv9dd5 gtGddzJKt9MH5GPzHPaByPWuKySv2PpIs7j0VTenDEfoCYGEJ67yXKIdXfkyhf44 yDWrPIN/JnRcjR6xPQLCXI8w/C8MHGFz1ynR03yJ5ZvILssPTaY= =iaUe -----END PGP SIGNATURE----- --QDuqjw5mtcb8cj4X--