linux-kernel - Re: [linux-sunxi] Re: [PATCH v3 3/5] drm: panel: Add Xingbangda XBD599 panel (ST7703 controller)

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Message-ID: <20200617020049.iz6vujrs25kuipl6@core.my.home>
Date:   Wed, 17 Jun 2020 04:00:49 +0200
From:   Ondřej Jirman <megous@...ous.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-sunxi <linux-sunxi@...glegroups.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, Icenowy Zheng <icenowy@...c.io>,
        "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Samuel Holland <samuel@...lland.org>,
        Martijn Braam <martijn@...xit.nl>, Luca Weiss <luca@...tu.xyz>,
        Bhushan Shah <bshah@....org>
Subject: Re: [linux-sunxi] Re: [PATCH v3 3/5] drm: panel: Add Xingbangda
 XBD599 panel (ST7703 controller)

Hello Linus,

On Tue, May 26, 2020 at 01:32:25PM +0200, Linus Walleij wrote:
> Hi Ondrej,
> 

[...]

> > +       dsi_dcs_write_seq(dsi, ST7703_CMD_SETGIP1,
> > +                         0x82, 0x10, 0x06, 0x05, 0xA2, 0x0A, 0xA5, 0x12,
> > +                         0x31, 0x23, 0x37, 0x83, 0x04, 0xBC, 0x27, 0x38,
> > +                         0x0C, 0x00, 0x03, 0x00, 0x00, 0x00, 0x0C, 0x00,
> > +                         0x03, 0x00, 0x00, 0x00, 0x75, 0x75, 0x31, 0x88,
> > +                         0x88, 0x88, 0x88, 0x88, 0x88, 0x13, 0x88, 0x64,
> > +                         0x64, 0x20, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88,
> > +                         0x02, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> > +                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
> > +       dsi_dcs_write_seq(dsi, ST7703_CMD_SETGIP2,
> > +                         0x02, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> > +                         0x00, 0x00, 0x00, 0x00, 0x02, 0x46, 0x02, 0x88,
> > +                         0x88, 0x88, 0x88, 0x88, 0x88, 0x64, 0x88, 0x13,
> > +                         0x57, 0x13, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88,
> > +                         0x75, 0x88, 0x23, 0x14, 0x00, 0x00, 0x02, 0x00,
> > +                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> > +                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x0A,
> > +                         0xA5, 0x00, 0x00, 0x00, 0x00);
> > +       dsi_dcs_write_seq(dsi, ST7703_CMD_SETGAMMA,
> > +                         0x00, 0x09, 0x0D, 0x23, 0x27, 0x3C, 0x41, 0x35,
> > +                         0x07, 0x0D, 0x0E, 0x12, 0x13, 0x10, 0x12, 0x12,
> > +                         0x18, 0x00, 0x09, 0x0D, 0x23, 0x27, 0x3C, 0x41,
> > +                         0x35, 0x07, 0x0D, 0x0E, 0x12, 0x13, 0x10, 0x12,
> > +                         0x12, 0x18);
> > +       msleep(20);
> 
> This stuff is really hard or impossible to understand without the
> datasheet.
> 
> In my previous review I wrote:
> 
> It appears that the Himax HX8363 is using the same display controller
> if you look at the datasheet:
> http://www.datasheet-pdf.com/PDF/HX8369-A-Datasheet-Himax-729024
> There you find an explanation to some of the commands.

It is st7703, and we have a fairly complete datasheet available
publicly. I posted links in the cover letter.

> That means, try to get rid of as much of the magic bytes as you can
> and use proper #defines. I know it takes some work but the result
> is so much more useful and readable.

I've added some descriptions from the datasheet as comments next
to the values in v4.

Thank you and regards,
	o.

> Further I wrote:
> 
> You should definately insert code to read the MTP bytes:
> 0xDA manufacturer
> 0xDB driver version
> 0xDC LCD module/driver
> And print these, se e.g. my newly added NT35510 driver or
> the Sony ACX424AKP driver.
> 
> So please do that.
> 
> Yours,
> Linus Walleij
> 
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