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[83.233.6.197]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5944a5a0b7esm5951757e87.109.2025.11.12.07.39.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Nov 2025 07:39:49 -0800 (PST) Date: Wed, 12 Nov 2025 16:39:47 +0100 From: Marcus Folkesson To: Lars Rask Cc: "david@lechnology.com" , "jagan@amarulasolutions.com" , "agx@sigxcpu.org" , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , Kernel , Amir Dawd Seid , Johan Adolfsson , Daniel Larsson Persson Subject: Re: [RFC] What to base new driver for Raystar RDX0063 display panel using Sitronix ST75156 chip on? Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ijoNkkVX71GLNuQ2" Content-Disposition: inline In-Reply-To: --ijoNkkVX71GLNuQ2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Lars, On Wed, Nov 12, 2025 at 03:08:08PM +0000, Lars Rask wrote: > Hi, > I'm trying to create a driver for a small lcd display called Raystar RDX0= 063 that is using the > Sitronix ST75156 chip. The display is used in SPI 4 wire mode similar to = many other tiny MIPI > DBI displays, but the register set and framebuffer format is not MIPI DBI= compliant, since each > byte sent is actually 1 column of 8 rows. >=20 > The datasheets for the Raystar RDX0063 display and the Sitronix ST75156 c= hip are unfortunately > not publicly available, but you can find the datasheet for Sitronix ST756= 7 (which is similar to=20 > ST75156) here: https://www.topwaydisplay.com/sites/default/files/2020-05/= ST7567.pdf Support for ST7567 is mainlined (st7571 driver), and once this [1] series is applied, it should also support the SPI interface. Hard to tell without seeing the datasheet for ST75156, but if it's similar to ST7567, you might be able to just add an entry in the st7571 driver for it. >=20 > The main difference seems to be that ST75156 supports a higher resolution= than ST7567, > as can be seen here:=20 > https://www.sitronix.com.tw/en/products/industrial-display-driver-ic/mono= -stn-lcd-driver-ic This is how st7567 is defined: const struct st7571_panel_data st7567_config =3D { .init =3D st7567_lcd_init, .parse_dt =3D st7567_parse_dt, .constraints =3D { .min_nlines =3D 1, .max_nlines =3D 64, .min_ncols =3D 128, .max_ncols =3D 128, .support_grayscale =3D false, }, }; I think a similar structure for ST75156 with is enough. >=20 > As a first attempt to create the driver, the panel-mipi-dbi driver was ex= tended with "tweaks" > to support non MIPI DBI panels. This seems to work. However, after some d= iscussion with the > maintainer that is no longer active (https://github.com/notro/panel-mipi-= dbi/discussions/14) > the conclusion was that these "tweaks" were not upstreamable, and that I = need to create a new > driver specifically for the Raystar RDX0063 display panel using the Sitro= nix st75156 chip > instead. >=20 > In order to make my driver upstreamable, which driver should I be "inspir= ed" by (i.e copy and modify) > and base my work on? The drivers in drivers/gpu/drm/sitronix/ and drivers= /gpu/drm/tiny/ usually uses > struct mipi_dbi_dev and mipi_db_command() helpers, but drivers/gpu/drm/pa= nel/panel-sitronix-st7789v.c > does not. >=20 > Should I create my new driver as /gpu/drm/sitronix/st75156.c and use mipi= _dbi helpers where applicable? > If it is preferable to avoid using the mipi dbi helpers, is there another= set of helper functions that > I should use instead? >=20 > Best regards > /Lars Rask [1] https://lists.freedesktop.org/archives/dri-devel/2025-October/532431.ht= ml Best regards, Marcus Folkesson --ijoNkkVX71GLNuQ2 Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEBVGi6LZstU1kwSxliIBOb1ldUjIFAmkUqj4ACgkQiIBOb1ld UjIwBRAAyVBRr+dj9P84ET1/ILprKUFBu+JfI+tKodLXmLdii2HbxF0cmHeA1RAt RRZKnPiJ57IWFI7dolRE4shsRvW026F9aRRIcKRP+cB+p+szTZryhbm6Hc61Uj1J nPYsAOSh6ynFsAFGJypFd1irqhTMIfhTrACZ7DXrd8jwKHJR1diyv4LT7QdLm0R5 Hx73yvI5x19IkEEoIc+TR1BqSVSxgo860YdClgfsWubLLRV9GBV+FKz6BCD4fwXk mxgUtwcAh0iwKz7GVNs8wFiHVbYsaLtwmFElVlfKAhpN2O3mI3ubrwR14yUw9gGk 7BbCQKoOh/cFBhE+5e19BBuXILZ9nJm4q/YqZgC3l8YeC2j0pwJprCV6PvhtHJly D6pjfcnyMnNXu3oZEolxNOcRwwc/XQp0ANDPQ2+G4dTwslKrpxN7n857/anRMKg1 GdsHaTnMzwVARh2rBDfPbaPHYrY4a/GwHIBPYnVldehAVkIclcS/XCD824lAhhh/ rx2Sxsv+zYN3qgZ1/ztZagkyyGe2jUECiEWdrxzptUeviPOtG5FNPaOTSFi0xpZS MJVFSD80ZCkUyT9vDgvp4ovxwmd8yKFTuyiow5RDzY2jqivNajHlKfmcJt6GPHQh Hgs2L5Pi+pj4fWuNk/4EMPFiRcUhVjH9aEH0ML7ZeRFTw6FtTyQ= =ZOZV -----END PGP SIGNATURE----- --ijoNkkVX71GLNuQ2--