Hi Alex, On 11 August 2016 at 05:38, Alexander Graf <ag...@suse.de> wrote: > On the raspberry pi, you can disable the serial port to gain dynamic frequency > scaling which can get handy at times. > > However, in such a configuration the serial controller gets its rx queue > filled > up with zero bytes which then happily get transmitted on to whoever calls > getc() today. > > This patch adds detection logic for that case by checking whether the RX pin > is > mapped to GPIO15 and disables the mini uart if it is not mapped properly. > > That way we can leave the driver enabled in the tree and can determine during > runtime whether serial is usable or not, having a single binary that allows > for > uart and non-uart operation. > > Signed-off-by: Alexander Graf <ag...@suse.de> > > --- > > v2 -> v3: > > - Disable and detect pinmux in board file > --- > board/raspberrypi/rpi/rpi.c | 29 +++++++++++++++++++++++++++++ > configs/rpi_3_32b_defconfig | 1 + > configs/rpi_3_defconfig | 1 + > include/configs/rpi.h | 1 + > 4 files changed, 32 insertions(+) > > diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c > index 4c8253d..20b0d1b 100644 > --- a/board/raspberrypi/rpi/rpi.c > +++ b/board/raspberrypi/rpi/rpi.c > @@ -453,6 +453,35 @@ int board_init(void) > return power_on_module(BCM2835_MBOX_POWER_DEVID_USB_HCD); > } > > +static bool rpi_is_serial_active(void) > +{ > +#ifndef CONFIG_PL01X_SERIAL > + int serial_gpio = 15; > + struct udevice *dev; > + > + /* > + * The RPi3 disables the mini uart by default. The easiest way to find > + * out whether it is available is to check if the pin is muxed. > + */ > + if (uclass_first_device(UCLASS_GPIO, &dev) || !dev) > + return true; > + > + if (bcm2835_gpio_get_func_id(dev, serial_gpio) != BCM2835_GPIO_ALT5) > + return false;
Do you mean gpio_get_function()? > +#endif > + > + return true; > +} > + > +int board_late_init(void) > +{ > + /* Disable mini-UART I/O if it's not pinmuxed to our pins */ > + if (!rpi_is_serial_active()) > + gd->cur_serial_dev = NULL; > + > + return 0; > +} > + > int board_mmc_init(bd_t *bis) > { > ALLOC_CACHE_ALIGN_BUFFER(struct msg_get_clock_rate, msg_clk, 1); > diff --git a/configs/rpi_3_32b_defconfig b/configs/rpi_3_32b_defconfig > index 922e01b..4c2f106 100644 > --- a/configs/rpi_3_32b_defconfig > +++ b/configs/rpi_3_32b_defconfig > @@ -20,3 +20,4 @@ CONFIG_CMD_FAT=y > CONFIG_CMD_FS_GENERIC=y > CONFIG_PHYS_TO_BUS=y > CONFIG_OF_LIBFDT=y > +# CONFIG_REQUIRE_SERIAL_CONSOLE is not set > diff --git a/configs/rpi_3_defconfig b/configs/rpi_3_defconfig > index bff92df..288214c 100644 > --- a/configs/rpi_3_defconfig > +++ b/configs/rpi_3_defconfig > @@ -19,3 +19,4 @@ CONFIG_CMD_FAT=y > CONFIG_CMD_FS_GENERIC=y > CONFIG_PHYS_TO_BUS=y > CONFIG_OF_LIBFDT=y > +# CONFIG_REQUIRE_SERIAL_CONSOLE is not set > diff --git a/include/configs/rpi.h b/include/configs/rpi.h > index b5543f4..e3b890a 100644 > --- a/include/configs/rpi.h > +++ b/include/configs/rpi.h > @@ -22,6 +22,7 @@ > > /* Architecture, CPU, etc.*/ > #define CONFIG_ARCH_CPU_INIT > +#define CONFIG_BOARD_LATE_INIT > > /* Use SoC timer for AArch32, but architected timer for AArch64 */ > #ifndef CONFIG_ARM64 > -- > 1.8.5.6 > Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot