Why is LS1043 MTU limited to 2K, not 4K?

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Why is LS1043 MTU limited to 2K, not 4K?

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lpm
Contributor I

Hi!

In the fsl_dpa driver, if dpaa_errata_a010022 is true, max_mtu is set to DPA_BP_RAW_SIZE dpaa_errata_a010022 is true.

Errata A-010022 says that buffers can be 4096 bytes if aligned to 4096, so shouldn't it be possible to have MTU > 2K? 

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yipingwang
NXP TechSupport
NXP TechSupport

Hello Lars Petter Mostad,

The MTU currently defaults to a maximum of 1522. If you want a higher MTU, it is necessary to pass fsl_fm_max_frm=N on the kernel bootargs, where "N" is the desired maximum MTU + 22.

Previously Scatter Gather frames and Jumbo frames are not supported on LS1043A due to the FMan A010022 errata.

Jumbo frame support on LS1043 on top of LSDK 1712. Adapt the A010022 errata workaround to accommodate this request.

The attached patch enables Jumbo frames on LS1043A. Need to adapt it to the latest code base for LSDK 18.09.


Have a great day,
TIC

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yipingwang
NXP TechSupport
NXP TechSupport

Hello Lars Petter Mostad,

The MTU currently defaults to a maximum of 1522. If you want a higher MTU, it is necessary to pass fsl_fm_max_frm=N on the kernel bootargs, where "N" is the desired maximum MTU + 22.

Previously Scatter Gather frames and Jumbo frames are not supported on LS1043A due to the FMan A010022 errata.

Jumbo frame support on LS1043 on top of LSDK 1712. Adapt the A010022 errata workaround to accommodate this request.

The attached patch enables Jumbo frames on LS1043A. Need to adapt it to the latest code base for LSDK 18.09.


Have a great day,
TIC

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

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