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Commit 0b7a43d3 authored by Alexandre TORGUE's avatar Alexandre TORGUE Committed by David S. Miller
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Documentation: networking: update stmmac 



Update stmmac driver documentation according to new GMAC 4.x family.

Signed-off-by: default avatarAlexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f748be53

Documentation/networking/stmmac.txt

+38 −6
Original line number Diff line number Diff line 
       STMicroelectronics 10/100/1000 Synopsys Ethernet driver



Copyright (C) 2007-2014  STMicroelectronics Ltd

Copyright (C) 2007-2015  STMicroelectronics Ltd

Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>



This is the driver for the MAC 10/100/1000 on-chip Ethernet controllers
@@ -138,6 +138,8 @@ struct plat_stmmacenet_data { 
	int (*init)(struct platform_device *pdev, void *priv);

	void (*exit)(struct platform_device *pdev, void *priv);

	void *bsp_priv;

	int has_gmac4;

	bool tso_en;

};



Where:
@@ -181,6 +183,8 @@ Where: 
	     registers.  init/exit callbacks should not use or modify

	     platform data.

 o bsp_priv: another private pointer.

 o has_gmac4: uses GMAC4 core.

 o tso_en: Enables TSO (TCP Segmentation Offload) feature.



For MDIO bus The we have:
@@ -278,6 +282,13 @@ Please see the following document: 
 o stmmac_ethtool.c: to implement the ethtool support;

 o stmmac.h: private driver structure;

 o common.h: common definitions and VFTs;

 o mmc_core.c/mmc.h: Management MAC Counters;

 o stmmac_hwtstamp.c: HW timestamp support for PTP;

 o stmmac_ptp.c: PTP 1588 clock;

 o dwmac-<XXX>.c: these are for the platform glue-logic file; e.g. dwmac-sti.c

   for STMicroelectronics SoCs.



- GMAC 3.x

 o descs.h: descriptor structure definitions;

 o dwmac1000_core.c: dwmac GiGa core functions;

 o dwmac1000_dma.c: dma functions for the GMAC chip;
@@ -289,11 +300,32 @@ Please see the following document: 
 o enh_desc.c: functions for handling enhanced descriptors;

 o norm_desc.c: functions for handling normal descriptors;

 o chain_mode.c/ring_mode.c:: functions to manage RING/CHAINED modes;

 o mmc_core.c/mmc.h: Management MAC Counters;

 o stmmac_hwtstamp.c: HW timestamp support for PTP;

 o stmmac_ptp.c: PTP 1588 clock;

 o dwmac-<XXX>.c: these are for the platform glue-logic file; e.g. dwmac-sti.c

   for STMicroelectronics SoCs.



- GMAC4.x generation

 o dwmac4_core.c: dwmac GMAC4.x core functions;

 o dwmac4_desc.c: functions for handling GMAC4.x descriptors;

 o dwmac4_descs.h: descriptor definitions;

 o dwmac4_dma.c: dma functions for the GMAC4.x chip;

 o dwmac4_dma.h: dma definitions for the GMAC4.x chip;

 o dwmac4.h: core definitions for the GMAC4.x chip;

 o dwmac4_lib.c: generic GMAC4.x functions;



4.12) TSO support (GMAC4.x)



TSO (Tcp Segmentation Offload) feature is supported by GMAC 4.x chip family.

When a packet is sent through TCP protocol, the TCP stack ensures that

the SKB provided to the low level driver (stmmac in our case) matches with

the maximum frame len (IP header + TCP header + payload <= 1500 bytes (for

MTU set to 1500)). It means that if an application using TCP want to send a

packet which will have a length (after adding headers) > 1514 the packet

will be split in several TCP packets: The data payload is split and headers

(TCP/IP ..) are added. It is done by software.



When TSO is enabled, the TCP stack doesn't care about the maximum frame

length and provide SKB packet to stmmac as it is. The GMAC IP will have to

perform the segmentation by it self to match with maximum frame length.



This feature can be enabled in device tree through "snps,tso" entry.



5) Debug Information