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SubjectRe: [PATCH 4/6] ARM: dts: sun8i: a83t: Add device node for CSI (Camera Sensor Interface)
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Hi,

Le mercredi 10 avril 2019 à 00:00 +0200, Ondřej Jirman a écrit :
> On Tue, Apr 09, 2019 at 10:28:18AM +0200, Maxime Ripard wrote:
> > On Tue, Apr 09, 2019 at 04:07:34PM +0800, Chen-Yu Tsai wrote:
> > > On Tue, Apr 9, 2019 at 3:58 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > > > On Tue, Apr 09, 2019 at 12:57:42AM +0800, Chen-Yu Tsai wrote:
> > > > > From: Chen-Yu Tsai <wens@csie.org>
> > > > >
> > > > > The A83T SoC has a camera sensor interface (known as CSI in Allwinner
> > > > > lingo), which is similar to the one found on the A64 and H3. The only
> > > > > difference seems to be that support of MIPI CSI through a connected
> > > > > MIPI CSI-2 bridge.
> > > > >
> > > > > Add a device node for it, and pinctrl nodes for the commonly used MCLK
> > > > > and 8-bit parallel interface. The property /omit-if-no-ref/ is added to
> > > > > the pinctrl nodes to keep the device tree blob size down if they are
> > > > > unused.
> > > > >
> > > > > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> > > > > ---
> > > > > arch/arm/boot/dts/sun8i-a83t.dtsi | 31 +++++++++++++++++++++++++++++++
> > > > > 1 file changed, 31 insertions(+)
> > > > >
> > > > > diff --git a/arch/arm/boot/dts/sun8i-a83t.dtsi b/arch/arm/boot/dts/sun8i-a83t.dtsi
> > > > > index f739b88efb53..0c52f945fd5f 100644
> > > > > --- a/arch/arm/boot/dts/sun8i-a83t.dtsi
> > > > > +++ b/arch/arm/boot/dts/sun8i-a83t.dtsi
> > > > > @@ -682,6 +682,20 @@
> > > > > #interrupt-cells = <3>;
> > > > > #gpio-cells = <3>;
> > > > >
> > > > > + /omit-if-no-ref/
> > > > > + csi_8bit_parallel_pins: csi-8bit-parallel-pins {
> > > > > + pins = "PE0", "PE2", "PE3", "PE6", "PE7",
> > > > > + "PE8", "PE9", "PE10", "PE11",
> > > > > + "PE12", "PE13";
> > > > > + function = "csi";
> > > > > + };
> > > > > +
> > > > > + /omit-if-no-ref/
> > > > > + csi_mclk_pin: csi-mclk-pin {
> > > > > + pins = "PE1";
> > > > > + function = "csi";
> > > > > + };
> > > > > +
> > > > > emac_rgmii_pins: emac-rgmii-pins {
> > > > > pins = "PD2", "PD3", "PD4", "PD5", "PD6", "PD7",
> > > > > "PD11", "PD12", "PD13", "PD14", "PD18",
> > > > > @@ -994,6 +1008,23 @@
> > > > > interrupts = <GIC_PPI 9 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_HIGH)>;
> > > > > };
> > > > >
> > > > > + csi: camera@1cb0000 {
> > > > > + compatible = "allwinner,sun8i-a83t-csi";
> > > > > + reg = <0x01cb0000 0x1000>;
> > > > > + interrupts = <GIC_SPI 84 IRQ_TYPE_LEVEL_HIGH>;
> > > > > + clocks = <&ccu CLK_BUS_CSI>,
> > > > > + <&ccu CLK_CSI_SCLK>,
> > > > > + <&ccu CLK_DRAM_CSI>;
> > > > > + clock-names = "bus", "mod", "ram";
> > > > > + resets = <&ccu RST_BUS_CSI>;
> > > > > + status = "disabled";
> > > > > +
> > > > > + csi_in: port {
> > > > > + #address-cells = <1>;
> > > > > + #size-cells = <0>;
> > > >
> > > > If we expect a single enpoint, then we don't need the address-cells
> > > > and size-cells properties.
> > >
> > > I wouldn't bet on anything. The way the Q8 tablets did front/back cameras
> > > is kind of genius if not very hacky. They have two "identical" sensors
> > > on the same I2C bus and CSI bus, with shared reset line but separate
> > > shutdown lines. Since they are identical, they also have the same I2C
> > > address. I haven't figured out how to model this in the device tree.
> > >
> > > The point is, it's perfectly possible to have two or more sensors use
> > > the same controller, provided only one be active at a time.
> >
> > Right, but I guess the common case would be to have a single sensor,
> > where that wouldn't be needed.
> >
> > In odd cases, we can always specify it in the DTS, and if it becomes
> > common enough, we can move it to the DTSI.
>
> I'm planning on having two sensors there, in a less arcane setup,
> though - no shared resets, and different I2C addresses.
>
> Anyway, I can confirm that CSI driver works fine on A83T with just
> a DTSI patch, even without the clock patch in this series. I've been
> running it for quite a while that way without any issues (different
> camera chip than the ones being used by wens).

That's quite nice to hear! I would be interested in getting some
insight on which sensors are known to work and which are broken or have
limitations.

Would you happen to have a list of the sensors that you tested and
whether you encountered such issues with them?

Cheers,

Paul

--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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