VPU on imx6 solo

[skappen]

The iram size on reserved for vpu on imx6 solo seems to be zero, the vpu node in  device tree file passes zero as iram size where as imx6qd it is 0x2100.

arch/arm/boot/dts/imx6dl.dtsi

vpu@02040000 {

                iramsize = <0>;

                status = "okay";

            };

Our custom video driver uses VPU APIs for h264 encoding and during initialization it gives a warning message as

" VPU iram is less than needed, some parts don't use iram"

The internal ram in imx solo is 128 KB. Why iram memory is not been used for vpu on imx6 solo ?

[Yuri · Accepted solution]

Hello,

  Basically, FSL Linux BSP uses the IRAM. Say for i.MX6Q, where

IRAM size is 256K, up to 132K may be reserved for the VPU.

Since IRAM size of the i.MX6S is not so big, there is no IRAM reservation

for VPU. As for VPU API, please refer to section 3.2.2.33 (iram_t) of

“i.MX_6_VPU_Application_Programming_Interface_Linux_Reference_Manual.pdf”.

Looks like You should not use IRAM with VPU of i.MX6S.

     https://www.freescale.com/webapp/Download?colCode=L3.14.28_1.0.0_iMX6QDLS_BUNDLE&appType=license&loc...

Have a great day,
Yuri

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[charlesung]

Hi Yuri,

If I am using the gstreamer imxvpuenc_h264 plugin, which piece of code I will have to change so I can correct for this problem? I have looked a few places but it is not clear to me where I need to change so the VPU will not use the IRAM.

Thanks,

Charles

[Yuri]

Hello,

  it is enough to  set  iramsize = <0> in the device tree file.

Regards,

Yuri.

[charlesung]

That is what I thought too when I looked at the driver. And I already have that in the dts file.

   vpu@02040000 {
    compatible = "fsl,imx6-vpu";
    reg = <0x2040000 0x3c000>;
    reg-names = "vpu_regs";
    interrupts = <0x0 0x3 0x1 0x0 0xc 0x4>;
    interrupt-names = "vpu_jpu_irq", "vpu_ipi_irq";
    clocks = <0x2 0xa8 0x2 0x8c 0x2 0x8e>;
    clock-names = "vpu_clk", "mmdc_ch0_axi", "ocram";
    iramsize = <0x0>;
    iram = <0xa>;
    resets = <0xb 0x1>;
    power-domains = <0xc 0x1>;
   };

But for some reason, it is still complaining about this when I ran the gstreamer pipeline that involves h264 encoding using the vpu. Can you think anything else that I may be missing?

Thanks,

Charles

[skappen]

Thanks Yuri, this was really helpful.