Re: [PATCH v2 2/2] ARM: dts: stm32: Enable MIPI DSI display support.

[Adrian Pop <pop.adrian61@xxxxxxxxx>]

Hello Hua,

Thank you for your review,

On Tue, Jul 14, 2020 at 6:37 AM Hua Dillon <dillonhua@xxxxxxxxx> wrote:
>
> Hi, Adrian,
>
> Just one suggestion for you.
>
> Adrian Pop <pop.adrian61@xxxxxxxxx> 于2020年7月3日周五 上午1:30写道：
> >
> > STM32f769-disco features a 4" MIPI DSI display: add support for it.
> > On Cortex-M7 DMA can't use cached memory. For this reason I use a dedicated
> > memory pool for DMA with no-cache attribute which is located at the end of
> >  RAM.
> >
> > Signed-off-by: Adrian Pop <pop.adrian61@xxxxxxxxx>
> > ---
> >  arch/arm/boot/dts/stm32f746.dtsi      | 34 +++++++++++++++++++
> >  arch/arm/boot/dts/stm32f769-disco.dts | 49 +++++++++++++++++++++++++++
> >  2 files changed, 83 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/stm32f746.dtsi b/arch/arm/boot/dts/stm32f746.dtsi
> > index 93c063796780..577a812ca01c 100644
> > --- a/arch/arm/boot/dts/stm32f746.dtsi
> > +++ b/arch/arm/boot/dts/stm32f746.dtsi
> > @@ -48,6 +48,19 @@ / {
> >         #address-cells = <1>;
> >         #size-cells = <1>;
> >
> > +       reserved-memory {
> > +               #address-cells = <1>;
> > +               #size-cells = <1>;
> > +               ranges;
> > +
> > +               linux,dma {
> > +                       compatible = "shared-dma-pool";
> > +                       linux,dma-default;
> > +                       no-map;
> > +                       reg = <0xc0f00000 0x100000>;
> > +               };
> > +       };
> > +
> Christoph Hellwig was submit a patch for !CONFIG_MMU platforms to support mmap.
> the patch is : 1fbf57d05302 dma-direct: re-enable mmap for !CONFIG_MMU
> i thought there is no need to create a reserved-memory for it.

Just tried with his patch, if I don't have the reserved-memory, I get:

[drm] Initialized stm 1.0.0 20170330 for 40016800.display-controller on minor 0
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5 at arch/arm/mm/dma-mapping-nommu.c:50 0xc000b8e9
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.8.0-rc1-next-20200616 #4
Hardware name: STM32 (Device Tree Support)
Workqueue: events 0xc0150fc1

This is the reason I added the reserved memory in the first place.

>
> >         clocks {
> >                 clk_hse: clk-hse {
> >                         #clock-cells = <0>;
> > @@ -75,6 +88,27 @@ clk_i2s_ckin: clk-i2s-ckin {
> >         };
> >
> >         soc {
> > +               ltdc: display-controller@40016800 {
> > +                       compatible = "st,stm32-ltdc";
> > +                       reg = <0x40016800 0x200>;
> > +                       interrupts = <88>, <89>;
> > +                       resets = <&rcc STM32F7_APB2_RESET(LTDC)>;
> > +                       clocks = <&rcc 1 CLK_LCD>;
> > +                       clock-names = "lcd";
> > +                       status = "disabled";
> > +               };
> > +
> > +               dsi: dsi@40016c00 {
> > +                       compatible = "st,stm32-dsi";
> > +                       reg = <0x40016c00 0x800>;
> > +                       interrupts = <98>;
> > +                       clocks = <&rcc 1 CLK_F769_DSI>, <&clk_hse>;
> > +                       clock-names = "pclk", "ref";
> > +                       resets = <&rcc STM32F7_APB2_RESET(DSI)>;
> > +                       reset-names = "apb";
> > +                       status = "disabled";
> > +               };
> > +
> >                 timer2: timer@40000000 {
> >                         compatible = "st,stm32-timer";
> >                         reg = <0x40000000 0x400>;
> > diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
> > index 1626e00bb2cb..a9e81b49809c 100644
> > --- a/arch/arm/boot/dts/stm32f769-disco.dts
> > +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> > @@ -153,3 +153,52 @@ &usbotg_hs {
> >         pinctrl-names = "default";
> >         status = "okay";
> >  };
> > +
> > +&dsi {
> > +       #address-cells = <1>;
> > +       #size-cells = <0>;
> > +       status = "okay";
> > +
> > +       ports {
> > +               #address-cells = <1>;
> > +               #size-cells = <0>;
> > +
> > +               port@0 {
> > +                       reg = <0>;
> > +                       dsi_in: endpoint {
> > +                               remote-endpoint = <&ltdc_out_dsi>;
> > +                       };
> > +               };
> > +
> > +               port@1 {
> > +                       reg = <1>;
> > +                       dsi_out: endpoint {
> > +                               remote-endpoint = <&dsi_in_panel>;
> > +                       };
> > +               };
> > +
> > +       };
> > +
> > +       panel: panel {
> > +               compatible = "orisetech,otm8009a";
> > +               reg = <0>;
> > +               reset-gpios = <&gpioj 15 GPIO_ACTIVE_LOW>;
> > +               status = "okay";
> > +
> > +               port {
> > +                       dsi_in_panel: endpoint {
> > +                               remote-endpoint = <&dsi_out>;
> > +                       };
> > +               };
> > +       };
> > +};
> > +
> > +&ltdc {
> > +       status = "okay";
> > +
> > +       port {
> > +               ltdc_out_dsi: endpoint {
> > +                       remote-endpoint = <&dsi_in>;
> > +               };
> > +       };
> > +};
> > --
> > 2.27.0
> >
> >
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> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Regards,
Adrian