[U-Boot] [PATCH] imx: Introduce CONFIG_SPL_FORCE_MMC_BOOT to force MMC boot on falcon mode

Lukasz Majewski
2019-09-03T21:43:57Z

This change tries to fix the following problem:

- The board boots (to be more precise - ROM loads SPL) from a slow SPI-NOR
memory.
As a result the spl_boot_device() will return SPI-NOR as a boot device
(which is correct).

- The problem is that in 'falcon boot' the eMMC is used as a boot medium to
load kernel from its partition.
Calling spl_boot_device() will break things as it returns SPI-NOR device.

To fix this issue the new CONFIG_SPL_FORCE_MMC_BOOT Kconfig flag is
introduced to handle this special use case. By default it is not defined,
so there is no change in the legacy code flow.

Signed-off-by: Lukasz Majewski <lukma@denx.de>

---

This patch is a follow up of previous discussion/fix:
https://patchwork.ozlabs.org/patch/796237/

Travis-CI:
https://travis-ci.org/lmajewski/u-boot-dfu/builds/580272414
---
arch/arm/mach-imx/spl.c | 11 +++++++++++
common/spl/Kconfig | 7 +++++++
2 files changed, 18 insertions(+)

diff --git a/arch/arm/mach-imx/spl.c b/arch/arm/mach-imx/spl.c
index 1f230aca3397..daa3d8f7ed94 100644
--- a/arch/arm/mach-imx/spl.c
+++ b/arch/arm/mach-imx/spl.c
@@ -178,7 +178,18 @@ int g_dnl_bind_fixup(struct usb_device_descriptor *dev, const char *name)
/* called from spl_mmc to see type of boot mode for storage (RAW or FAT) */
u32 spl_boot_mode(const u32 boot_device)
{
+/*
+ * When CONFIG_SPL_FORCE_MMC_BOOT is defined the 'boot_device' is used
+ * unconditionally to decide about device to use for booting.
+ * This is crucial for falcon boot mode, when board boots up (i.e. ROM
+ * loads SPL) from slow SPI-NOR memory and afterwards the SPL's 'falcon' boot
+ * mode is used to load Linux OS from eMMC partition.
+ */
+#ifdef CONFIG_SPL_FORCE_MMC_BOOT
+ switch (boot_device) {
+#else
switch (spl_boot_device()) {
+#endif
/* for MMC return either RAW or FAT mode */
case BOOT_DEVICE_MMC1:
case BOOT_DEVICE_MMC2:
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index f467eca2be72..3460beb62d59 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -607,6 +607,13 @@ config SPL_MMC_SUPPORT
this option to build the drivers in drivers/mmc as part of an SPL
build.

+config SPL_FORCE_MMC_BOOT
+ bool "Force SPL's falcon boot from MMC"
+ depends on SPL_MMC_SUPPORT
+ default n
+ help
+ Force SPL's falcon boot to use MMC device for Linux kernel booting.
+
config SPL_MMC_TINY
bool "Tiny MMC framework in SPL"
depends on SPL_MMC_SUPPORT
--
2.11.0