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stmmac: cleanup documenation, make it match reality

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Fix english in documentation, make documentation match reality, remove
options that were removed from code.

Signed-off-by: Pavel Machek <pavel@denx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Machek 2016-12-01 11:32:18 +01:00 committed by David S. Miller
parent 2745529ac7
commit c6c60dae81
1 changed files with 23 additions and 24 deletions
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47
Documentation/networking/stmmac.txt
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@ -28,8 +28,6 @@ CONFIG_STMMAC_PCI: is to enable the pci driver.
2) Driver parameters list: 2) Driver parameters list:
debug: message level (0: no output, 16: all); debug: message level (0: no output, 16: all);
phyaddr: to manually provide the physical address to the PHY device; phyaddr: to manually provide the physical address to the PHY device;
dma_rxsize: DMA rx ring size;
dma_txsize: DMA tx ring size;
buf_sz: DMA buffer size; buf_sz: DMA buffer size;
tc: control the HW FIFO threshold; tc: control the HW FIFO threshold;
watchdog: transmit timeout (in milliseconds); watchdog: transmit timeout (in milliseconds);
@ -40,31 +38,31 @@ CONFIG_STMMAC_PCI: is to enable the pci driver.
3) Command line options 3) Command line options
Driver parameters can be also passed in command line by using: Driver parameters can be also passed in command line by using:
stmmaceth=dma_rxsize:128,dma_txsize:512 stmmaceth=watchdog:100,chain_mode=1
4) Driver information and notes 4) Driver information and notes
4.1) Transmit process 4.1) Transmit process
The xmit method is invoked when the kernel needs to transmit a packet; it sets The xmit method is invoked when the kernel needs to transmit a packet; it sets
the descriptors in the ring and informs the DMA engine that there is a packet the descriptors in the ring and informs the DMA engine, that there is a packet
ready to be transmitted. ready to be transmitted.
By default, the driver sets the NETIF_F_SG bit in the features field of the By default, the driver sets the NETIF_F_SG bit in the features field of the
net_device structure enabling the scatter-gather feature. This is true on net_device structure, enabling the scatter-gather feature. This is true on
chips and configurations where the checksum can be done in hardware. chips and configurations where the checksum can be done in hardware.
Once the controller has finished transmitting the packet, napi will be Once the controller has finished transmitting the packet, timer will be
scheduled to release the transmit resources. scheduled to release the transmit resources.
4.2) Receive process 4.2) Receive process
When one or more packets are received, an interrupt happens. The interrupts When one or more packets are received, an interrupt happens. The interrupts
are not queued so the driver has to scan all the descriptors in the ring during are not queued, so the driver has to scan all the descriptors in the ring during
the receive process. the receive process.
This is based on NAPI so the interrupt handler signals only if there is work This is based on NAPI, so the interrupt handler signals only if there is work
to be done, and it exits. to be done, and it exits.
Then the poll method will be scheduled at some future point. Then the poll method will be scheduled at some future point.
The incoming packets are stored, by the DMA, in a list of pre-allocated socket The incoming packets are stored, by the DMA, in a list of pre-allocated socket
buffers in order to avoid the memcpy (zero-copy). buffers in order to avoid the memcpy (zero-copy).
4.3) Interrupt Mitigation 4.3) Interrupt mitigation
The driver is able to mitigate the number of its DMA interrupts The driver is able to mitigate the number of its DMA interrupts
using NAPI for the reception on chips older than the 3.50. using NAPI for the reception on chips older than the 3.50.
New chips have an HW RX-Watchdog used for this mitigation. New chips have an HW RX-Watchdog used for this mitigation.
@ -88,19 +86,20 @@ the list, hence creating the explicit chaining in the descriptor itself,
whereas such explicit chaining is not possible in RING mode. whereas such explicit chaining is not possible in RING mode.
4.5.1) Extended descriptors 4.5.1) Extended descriptors
The extended descriptors give us information about the Ethernet payload The extended descriptors give us information about the Ethernet payload
when it is carrying PTP packets or TCP/UDP/ICMP over IP. when it is carrying PTP packets or TCP/UDP/ICMP over IP.
These are not available on GMAC Synopsys chips older than the 3.50. These are not available on GMAC Synopsys chips older than the 3.50.
At probe time the driver will decide if these can be actually used. At probe time the driver will decide if these can be actually used.
This support also is mandatory for PTPv2 because the extra descriptors This support also is mandatory for PTPv2 because the extra descriptors
are used for saving the hardware timestamps and Extended Status. are used for saving the hardware timestamps and Extended Status.
4.6) Ethtool support 4.6) Ethtool support
Ethtool is supported. Ethtool is supported.
For example, driver statistics (including RMON), internal errors can be taken For example, driver statistics (including RMON), internal errors can be taken
using: using:
# ethtool -S ethX command # ethtool -S ethX
command
4.7) Jumbo and Segmentation Offloading 4.7) Jumbo and Segmentation Offloading
Jumbo frames are supported and tested for the GMAC. Jumbo frames are supported and tested for the GMAC.
@ -275,11 +274,11 @@ Please see the following document:
Documentation/devicetree/bindings/net/stmmac.txt Documentation/devicetree/bindings/net/stmmac.txt
4.11) This is a summary of the content of some relevant files: 4.11) This is a summary of the content of some relevant files:
o stmmac_main.c: to implement the main network device driver; o stmmac_main.c: implements the main network device driver;
o stmmac_mdio.c: to provide mdio functions; o stmmac_mdio.c: provides MDIO functions;
o stmmac_pci: this the PCI driver; o stmmac_pci: this is the PCI driver;
o stmmac_platform.c: this the platform driver (OF supported) o stmmac_platform.c: this the platform driver (OF supported);
o stmmac_ethtool.c: to implement the ethtool support; o stmmac_ethtool.c: implements the ethtool support;
o stmmac.h: private driver structure; o stmmac.h: private driver structure;
o common.h: common definitions and VFTs; o common.h: common definitions and VFTs;
o mmc_core.c/mmc.h: Management MAC Counters; o mmc_core.c/mmc.h: Management MAC Counters;
@ -381,12 +380,12 @@ In addition to the basic timestamp features mentioned in IEEE 1588-2002
Timestamps, new GMAC cores support the advanced timestamp features. Timestamps, new GMAC cores support the advanced timestamp features.
IEEE 1588-2008 that can be enabled when configure the Kernel. IEEE 1588-2008 that can be enabled when configure the Kernel.
8) SGMII/RGMII supports 8) SGMII/RGMII support
New GMAC devices provide own way to manage RGMII/SGMII. New GMAC devices provide own way to manage RGMII/SGMII.
This information is available at run-time by looking at the This information is available at run-time by looking at the
HW capability register. This means that the stmmac can manage HW capability register. This means that the stmmac can manage
auto-negotiation and link status w/o using the PHYLIB stuff auto-negotiation and link status w/o using the PHYLIB stuff.
In fact, the HW provides a subset of extended registers to In fact, the HW provides a subset of extended registers to
restart the ANE, verify Full/Half duplex mode and Speed. restart the ANE, verify Full/Half duplex mode and Speed.
Also thanks to these registers it is possible to look at the Thanks to these registers, it is possible to look at the
Auto-negotiated Link Parter Ability. Auto-negotiated Link Parter Ability.