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What is the use case of "decoder_boot" and "encoder_boot" ?

Question asked by Raana on Aug 22, 2019
Latest reply on Aug 22, 2019 by igorpadykov

Dear Team,

 

I'm using 1GB DDR3 on our iMx8DX6 based custom board. Kernel version is, L4.14.62.

During analysis of current DDR/memory usage, we observed that Memtotal available is around 700 MB.

There the static allocation like shown in below line in dtsi file

               decoder_boot: decoder_boot@0x84000000 {

                        no-map;

                        reg = <0 0x84000000 0 0x2000000>;

                };

                encoder_boot: encoder_boot@0x86000000 {

                        no-map;

                        reg = <0 0x86000000 0 0x2000000>;

                };

etc...

 

mentioned in the structure of "reserved-memory" in "arch/arm64/boot/dts/freescale/fsl-imx8dx.dtsi" file.

 

We are not using Graphics & Framebuffer and still ~300MB is getting consumed by Kernel and with reserved/other components (i.e Memtotal is around 700MB – Checked using meminfo and free command).

We have modified the reserved size allocated for decoder_boot and encoder_boot and tested with this modified device tree file (dtb).

We could observe the increase in value of "MemTotal" (Memtotal confirmed using meminfo and free command).

 

Our observation is above fields are not affecting the board normal functionality.

Whether this "decoder_boot","encoder_boot","decoder_rpc","encoder_rpc" and "decoder_str" is really need to be reserved as we do not need to configure Graphics & Framebuffer ?

 

Please anybody can provide the exact use case of this field.

 

Best Regards,

J.P.Raja

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