From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giulio Benetti Date: Fri, 26 Oct 2018 15:40:06 +0200 Subject: [U-Boot] sunxi: add custom board In-Reply-To: <20181026110657.3bgphlnee4zepw7q@flea> References: <9fe3aa22-982b-082c-9de3-db875aa1c048@micronovasrl.com> <20181024175949.a2lrl5uctqt6js62@flea> <20181026110657.3bgphlnee4zepw7q@flea> Message-ID: <2926c1d9-53eb-d120-91ec-a0599a5dbd9b@micronovasrl.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: u-boot@lists.denx.de Il 26/10/2018 13:06, Maxime Ripard ha scritto: > On Thu, Oct 25, 2018 at 12:57:54PM +0200, Giulio Benetti wrote: >> Hello Maxime, >> >> Il 24/10/2018 19:59, Maxime Ripard ha scritto: >>> On Wed, Oct 24, 2018 at 03:59:56PM +0200, Giulio Benetti wrote: >>>> Hello Jagan and Maxime, >>>> >>>> I've looked around a lot, but I can't find a way to use the board/sunx= i: >>>> http://git.denx.de/?p=3Du-boot.git;a=3Dtree;f=3Dboard/sunxi;h=3D304ee6= b4cc8e075759d3bd0beb250b56f6901702;hb=3DHEAD >>>> >>>> to fit what we need. >>>> >>>> We have 5 gpios that control the max current setting on >>>> current-driver for Backlight biasing shunt kathode resistor, and I >>>> don't know where to place the code to set those pins. >>>> >>>> I would like to avoid to create another new board if possible, since >>>> board/sunxi has everything we need to make our board operative. >>>> In general, is there some sort of __weak__ hooks to be used to extend = an >>>> existing board? >>>> Because I understand that probably you wouldn't add this code I'm talk= ing >>>> about inside board/sunxi. >>>> >>>> This request is done with idea to upstream patch for this board. >>>> >>>> Can you help me? >>> >>> If that's backlight related, maybe you can just create a new backlight >>> driver? >> >> If it makes sense for sure we can. >> >> But please can you take a look at the schematics of current-driver with >> mosfets biasing power? >> https://pasteboard.co/HK4ChzF.png >> As you can see we bias BKL_K (Backlight Kathode) to slightly influence t= he >> shunt(R81+R76). >> I don't know how it could be useful for the others. >> >> We use that to handle different displays with the same board(A20 based). >> >> So does it make sense to write a driver? >> And if yes, I would think about adding: >> backlight_current.c under u-boot/drivers/video >> or another option could be to write a driver under: >> u-boot/drivers/power >> >> What do you think? >=20 > Maybe you can just create a regulator driver, with each current step > describing a step, just like gpio-regulator is doing for the voltage. That's a perfect example, thanks for pointing me. I would call it gpio-current-regulator and then I would place multiple=20 "states" instead of the current 2 states of gpio-regulator. Does it sound good? After some work maybe we should submit an RFC, right? Thank you Best regards --=20 Giulio Benetti CTO MICRONOVA SRL Sede: Via A. Niedda 3 - 35010 Vigonza (PD) Tel. 049/8931563 - Fax 049/8931346 Cod.Fiscale - P.IVA 02663420285 Capitale Sociale =E2=82=AC 26.000 i.v. Iscritta al Reg. Imprese di Padova N. 02663420285 Numero R.E.A. 258642