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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Thu, 14 May 2020 16:07:57 +0200
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Subject: Re: [PATCH v3 5/5] drm/panel: Add ilitek ili9341 driver
To:     dillon min <dillon.minfei@gmail.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre TORGUE <alexandre.torgue@st.com>,
        "thierry.reding@gmail.com" <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
        linux-clk <linux-clk@vger.kernel.org>
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On Thu, May 14, 2020 at 12:22 PM dillon min <dillon.minfei@gmail.com> wrote:

> > > +       /* Gamma */
> > > +       mipi_dbi_command(dbi, ILI9341_3GAMMA_EN, 0x00);
> > > +       mipi_dbi_command(dbi, MIPI_DCS_SET_GAMMA_CURVE, 0x01);
> > > +       mipi_dbi_command(dbi, ILI9341_PGAMMA,
> > > +                        0x0f, 0x31, 0x2b, 0x0c, 0x0e, 0x08, 0x4e, 0xf1,
> > > +                        0x37, 0x07, 0x10, 0x03, 0x0e, 0x09, 0x00);
> > > +       mipi_dbi_command(dbi, ILI9341_NGAMMA,
> > > +                        0x00, 0x0e, 0x14, 0x03, 0x11, 0x07, 0x31, 0xc1,
> > > +                        0x48, 0x08, 0x0f, 0x0c, 0x31, 0x36, 0x0f);
> >
> > It seems to be copies of the stuff above, but why is there a different
> > gamma if you use DBI?

> for dbi interface, currently i just copy the code from tiny/ili9341.c.
> as so many boards use this driver now, like raspberry pi, etc
> i'm afraid it's will not work after modification. so, just leave the
> original code there.

OK if you move it to ili9341_config it will be clear which panels
need this gamma and which panels need another gamma.

I think there should be one ili9341_config for the new st,*
variant and one for the old DBI variant.

> anther question:
> is there any panel driver have dbi & dpi or dpi & dsi supported? which
> i mean support
> two different panel interface in one driver.
> thanks

Usually you split the driver in three files becuase a driver can
only list one initcall, and also it makes it modularized.

There is nothing in-tree but look at my branch here:
https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-nomadik.git/log/?h=ux500-skomer-v5.7-rc1

You see how I split up the s6e63m0 driver in one SPI part
and one DSI part:
https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-nomadik.git/commit/?h=ux500-skomer-v5.7-rc1&id=6c0e1fb5df5fa8fa857dee65f6c0f54d06d158a7
https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-nomadik.git/commit/?h=ux500-skomer-v5.7-rc1&id=cfbf562cc709b53b62f5fbc7fedf176ffa17b088

The overall idea should work the same with DBI.

Yours,
Linus Walleij

Yours,
Linus Walleij