Hello, since modifying/setting CONFIG_GMAC_TX_DELAY in u-boot seems to be necessary to get GMAC work reliable on some boards I wonder whether GMAC_RX_DELAY isn't worth a look (with many A20 based boards we've here we experience big differences in TX and RX throughput).
The background is outlined here: http://lists.denx.de/pipermail/u-boot/2014-September/190239.html RX delay seems to be related to bits 5-7 of the GMAC clk register, TX delay is defined in bits 10-12. AFAIK this stuff is still undocumented so I decided to try to brute-force through all possible combinations. I tried to patch both 'board/sunxi/Kconfig' and 'board/sunxi/gmac.c' to be able to define 'CONFIG_GMAC_RX_DELAY' in defconfigs. Then I let a script create 64 different u-boot versions as debian packages to be able to test them automatically. It seems to make a difference. Currently I test an Olimex Lime2 and will provide results later (each test run takes approx. 90 seconds including reboot, 30 seconds iperf test, exchange of u-boot and next automated reboot). Can anyone please tell me whether these 2 u-boot modifications against v2015.04 (http://pastebin.com/adiWjzya) are correct to modify bits 5-7 of GMAC clk register: --- diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig index 2fcab60..4623de6 100644 --- a/board/sunxi/Kconfig +++ b/board/sunxi/Kconfig @@ -451,4 +451,10 @@ config GMAC_TX_DELAY ---help--- Set the GMAC Transmit Clock Delay Chain value. +config GMAC_RX_DELAY + int "GMAC Receive Clock Delay Chain" + default 0 + ---help--- + Set the GMAC Reveice Clock Delay Chain value. + endif diff --git a/board/sunxi/gmac.c b/board/sunxi/gmac.c index 8849132..1bce3ce 100644 --- a/board/sunxi/gmac.c +++ b/board/sunxi/gmac.c @@ -26,6 +26,8 @@ int sunxi_gmac_initialize(bd_t *bis) CCM_GMAC_CTRL_GPIT_RGMII); setbits_le32(&ccm->gmac_clk_cfg, CCM_GMAC_CTRL_TX_CLK_DELAY(CONFIG_GMAC_TX_DELAY)); + setbits_le32(&ccm->gmac_clk_cfg, + CCM_GMAC_CTRL_RX_CLK_DELAY(CONFIG_GMAC_RX_DELAY)); #else setbits_le32(&ccm->gmac_clk_cfg, CCM_GMAC_CTRL_TX_CLK_SRC_MII | CCM_GMAC_CTRL_GPIT_MII); -- Regards, Thomas -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
