Hi @tenk.wang@jasonl@goenjoy ,
after checking documentation of the VIM3[1] i concluded that JTAG is on the microsd pins.
i flashed my android image and tried to attach my olimex jtag adapter via an selfmade adapter
the pinout i tried is (sdcard from top to bottom 1 -8)
3 → TMS
5-> CLK
6->GND
7->TDO
8->TDI
I don’t have much experience with JTAG do i miss something here? openocd tries autoprobing so i don’t know if my conclusion is right. Has anybody more information?
Hi @jasonl thanks for coming back to me.
So i checked the arch64/boot/dts folder and noticed that for the amlogic tree there is no specified jtag
i greped for jtag and found an example from rockchip which exposes jtag over the sdcard.
So i guess the reason i don’t get any jtag is not because of my pinout, it’s because it’s not “active” or configured as jtag.
could i use something like that i got from the rk3399-gru.dtsi with adapted parameters?
513 &sdmmc {
514 status = "okay";
515
516 /*
517 * Note: configure "sdmmc_cd" as card detect even though it's actually
518 * hooked to ground. Because we specified "cd-gpios" below dw_mmc
519 * should be ignoring card detect anyway. Specifying the pin as
520 * sdmmc_cd means that even if you've got GRF_SOC_CON7[12] (force_jtag)
521 * turned on that the system will still make sure the port is
522 * configured as SDMMC and not JTAG.
523 */
524 pinctrl-names = "default";
525 pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_cd &sdmmc_cd_gpio
526 &sdmmc_bus4>;
527
528 bus-width = <4>;
529 cap-mmc-highspeed;
530 cap-sd-highspeed;
531 cd-gpios = <&gpio4 24 GPIO_ACTIVE_LOW>;
532 disable-wp;
533 sd-uhs-sdr12;
534 sd-uhs-sdr25;
535 sd-uhs-sdr50;
536 sd-uhs-sdr104;
537 vmmc-supply = <&pp3000_sd_slot>;
538 vqmmc-supply = <&ppvar_sd_card_io>;
539 };
or is it not possible? i made kgdb working but it would be better to have jtag debug capabilities.
Thank’s for your help!
EDIT: so in the meson-khadas-vim3.dtsi i found the &sd_emmc_b section where GPIOC_6 is pulled low
judging from the documentation “GPIOC_6 should not pulled low if GPIOC is not work as SDCARD”
i added this section to the khadas vim3*-*.dts files
102 &sd_emmc_b {
103 status = "okay";
104 pinctrl-0 = <&sdcard_c_pins>;
105 pinctrl-1 = <&sdcard_clk_gate_c_pins>;
106 pinctrl-names = "default", "clk-gate";
107
108 bus-width = <4>;
109 cap-sd-highspeed;
110 max-frequency = <50000000>;
111 disable-wp;
112
113 /*cd-gpios = <&gpio GPIOC_6 GPIO_ACTIVE_LOW>; */
114 vmmc-supply = <&vsys_3v3>;
115 vqmmc-supply = <&vsys_3v3>;
116 };
but it did not make any difference at all