On Wed, 20 Jul 2022 09:01:01 -0600 Simon Glass <s...@chromium.org> wrote:
> Hi Hugo, > > On Wed, 20 Jul 2022 at 04:54, Hugo Villeneuve <h...@hugovil.com> wrote: > > > > Hi, > > in board_early_init_f(), i call a custom function get_som_revision() to > > read some GPIOs that are used to determine the SOM revision. This function > > basically sets the iomux, and then uses > > gpio_request/gpio_direction_input/gpio_get_value functions to read the > > GPIOs. Then, this SOM revision information is used in > > board_fit_config_name_match() to decide which device tree to load. > > > > This works perfectly fine without CONFIG_DM_GPIO. However, if I enable > > CONFIG_DM_GPIO, it doesn't work anymore. There is an error when calling > > gpio_request(). > > > > What is the correct way to read GPIOs BEFORE any device tree is loaded? > > > > My board uses an MX6Q SOM. > > > > Here is part of the code I am using: > > > > ======================================== > > static iomux_v3_cfg_t const boardcfg_pads[] = { > > MX6_PAD_DISP0_DAT15__GPIO5_IO09 | MUX_PAD_CTRL(NO_PAD_CTRL), > > MX6_PAD_DISP0_DAT8__GPIO4_IO29 | MUX_PAD_CTRL(NO_PAD_CTRL), > > MX6_PAD_DISP0_DAT0__GPIO4_IO21 | MUX_PAD_CTRL(NO_PAD_CTRL), > > MX6_PAD_ENET_RXD0__GPIO1_IO27 | MUX_PAD_CTRL(NO_PAD_CTRL), > > MX6_PAD_ENET_RXD1__GPIO1_IO26 | MUX_PAD_CTRL(NO_PAD_CTRL), > > }; > > > > static int som_revision = -1; > > > > static const int boardcfg_gpio[] = { > > IMX_GPIO_NR(5, 9), > > IMX_GPIO_NR(4, 29), > > IMX_GPIO_NR(4, 21), > > IMX_GPIO_NR(1, 27), > > IMX_GPIO_NR(1, 26), > > }; > > > > static void get_som_revision(void) > > { > > int i; > > int rc; > > > > som_revision = 0; > > > > SETUP_IOMUX_PADS(boardcfg_pads); > > > > for (i = 0; i < ARRAY_SIZE(boardcfg_gpio); ++i) { > > int v; > > > > rc = gpio_request(boardcfg_gpio[i], "som-revision-gpio"); > > if (rc) { > > printf("%s(): gpio request %d failed\n", __func__, > > i); > > som_revision = -1; > > return; > > } > > > > gpio_direction_input(boardcfg_gpio[i]); > > v = gpio_get_value(boardcfg_gpio[i]); > > > > if ((v == 0) || (v == 1)) > > som_revision |= v << i; > > else { > > som_revision = -1; > > return; > > } > > } > > } > > > > int board_early_init_f(void) > > { > > setup_iomux_uart(); > > get_som_revision(); > > > > return 0; > > } > > > > ======================================== > > Well driver model needs the device tree to init, for example DM_GPIO > cannot operate without one unless you are hacking around with > platdata, which is a bit of a pain. > > One option you might have is to use a general DT before relocation, > then figure out which one you really want to use and select that for > post relocation. That works better with driver model. > > Regards, > Simon Hi Simon, I finally fixed the problem by hacking the mxc_gpio driver and simply enabling the DM_FLAG_PRE_RELOC flag with this simple patch: diff --git a/drivers/gpio/mxc_gpio.c b/drivers/gpio/mxc_gpio.c index 3cc0e7f353..be2bc6d655 100644 --- a/drivers/gpio/mxc_gpio.c +++ b/drivers/gpio/mxc_gpio.c @@ -396,6 +396,7 @@ U_BOOT_DRIVER(gpio_mxc) = { .priv_auto = sizeof(struct mxc_bank_info), .of_match = mxc_gpio_ids, .bind = mxc_gpio_bind, + .flags = DM_FLAG_PRE_RELOC, }; DM_DRIVER_ALIAS(gpio_mxc, fsl_imx6q_gpio) No other changes were required. However, this is probably not a solution that would get accepted into mainline U-Boot, or not? -- Hugo Villeneuve <h...@hugovil.com>