diff options
Diffstat (limited to 'Documentation/networking/stmmac.txt')
| -rw-r--r-- | Documentation/networking/stmmac.txt | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt index ef9ee71..f9fa6db 100644 --- a/Documentation/networking/stmmac.txt +++ b/Documentation/networking/stmmac.txt @@ -29,11 +29,9 @@ The kernel configuration option is STMMAC_ETH: dma_txsize: DMA tx ring size; buf_sz: DMA buffer size; tc: control the HW FIFO threshold; - tx_coe: Enable/Disable Tx Checksum Offload engine; watchdog: transmit timeout (in milliseconds); flow_ctrl: Flow control ability [on/off]; pause: Flow Control Pause Time; - tmrate: timer period (only if timer optimisation is configured). 3) Command line options Driver parameters can be also passed in command line by using: @@ -60,17 +58,19 @@ 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 buffers in order to avoid the memcpy (Zero-copy). -4.3) Timer-Driver Interrupt -Instead of having the device that asynchronously notifies the frame receptions, -the driver configures a timer to generate an interrupt at regular intervals. -Based on the granularity of the timer, the frames that are received by the -device will experience different levels of latency. Some NICs have dedicated -timer device to perform this task. STMMAC can use either the RTC device or the -TMU channel 2 on STLinux platforms. -The timers frequency can be passed to the driver as parameter; when change it, -take care of both hardware capability and network stability/performance impact. -Several performance tests on STM platforms showed this optimisation allows to -spare the CPU while having the maximum throughput. +4.3) Interrupt Mitigation +The driver is able to mitigate the number of its DMA interrupts +using NAPI for the reception on chips older than the 3.50. +New chips have an HW RX-Watchdog used for this mitigation. + +On Tx-side, the mitigation schema is based on a SW timer that calls the +tx function (stmmac_tx) to reclaim the resource after transmitting the +frames. +Also there is another parameter (like a threshold) used to program +the descriptors avoiding to set the interrupt on completion bit in +when the frame is sent (xmit). + +Mitigation parameters can be tuned by ethtool. 4.4) WOL Wake up on Lan feature through Magic and Unicast frames are supported for the @@ -121,6 +121,7 @@ struct plat_stmmacenet_data { int bugged_jumbo; int pmt; int force_sf_dma_mode; + int riwt_off; void (*fix_mac_speed)(void *priv, unsigned int speed); void (*bus_setup)(void __iomem *ioaddr); int (*init)(struct platform_device *pdev); @@ -156,6 +157,7 @@ Where: o pmt: core has the embedded power module (optional). o force_sf_dma_mode: force DMA to use the Store and Forward mode instead of the Threshold. + o riwt_off: force to disable the RX watchdog feature and switch to NAPI mode. o fix_mac_speed: this callback is used for modifying some syscfg registers (on ST SoCs) according to the link speed negotiated by the physical layer . |