Hello Stefano, Lukasz,
Am 05.09.2019 um 10:08 schrieb Stefano Babic:
On 04/09/19 12:35, Lukasz Majewski wrote:
On Wed, 4 Sep 2019 11:54:40 +0200
Lukasz Majewski <lu...@denx.de> wrote:
Hi Stefano, Heiko,
On 04/09/19 10:46, Lukasz Majewski wrote:
Hi Heiko,
Hello Lukasz,
added Stefano to cc as he is the imx custodian.
I've relied on patman ... Thanks for adding Stefano to CC.
Am 03.09.2019 um 23:43 schrieb Lukasz Majewski:
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 <lu...@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(+)
I have just similiar change for an imx6ull based board ...
Also one more of my boards uses this trick (i.MX28 based one).
just antoher usecase: In factory empty board boots into USB SDP
mode, and SPL gets loaded with usb_loader ... SPL detects a sd
card (there is no sd card slot mounted, mmc boot is disabled!
They attach only one for installing software)
So there is no dedicated SD card slot (also the mmc is disabled on
that point).
Instead, in the factory the sd card is attached to pads - just for
this time.
and boots U-Boot and system from sd card.
Than all software gets installed fully automated with the help of
swupdate ...
Ok.
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
Just dummy question .. couldn;t we switch to use always
boot_device?
Stefano has provided some rationale for the need of
spl_boot_device() in the previous version of this fix [1]:
https://patchwork.ozlabs.org/patch/796237/
In my case I had a board specific:
void board_boot_order(u32 *spl_boot_list)
{
spl_boot_list[0] = BOOT_DEVICE_MMC1;
spl_boot_list[1] = BOOT_DEVICE_SPI;
spl_boot_list[2] = BOOT_DEVICE_BOARD;
spl_boot_list[3] = BOOT_DEVICE_NONE;
}
which leads that BOOT_DEVICE_MMC1 is passed to spl_boot_mode()
Is your board normally booting from MMC or SPI-NOR (from where SoC
ROM loads SPL) ?
If MMC1 is not found, it tries to boot U-Boot from SPI, and if
this is empty, as fallback board go into USB SDP mode.
The weak function of board_boot_order is:
__weak void board_boot_order(u32 *spl_boot_list)
{
spl_boot_list[0] = spl_boot_device();
}
which is exactly what we pass to spl_boot_mode() ... so instead
calling spl_boot_device() twice we can use the passed boot_device
... and save the ifdef and new Kconfig option.
But may I oversee something ?
Please read the Stefano's reply from [1] - the spl_boot_device()
has a valid use cases as well.
Nevertheless, why do we need to add a new compiler switch if this
can be check into board code ? You just need that spl_boot_device()
returns the device you want (MMC for falcon boot).
Current status:
git grep -n "spl_boot_mode" | grep weak
common/spl/spl_mmc.c:287:u32 __weak spl_boot_mode(const u32
boot_device)
git grep -n "board_boot_order" | grep weak
common/spl/spl.c:491:__weak void board_boot_order(u32 *spl_boot_list)
The spl_boot_device() is defined in arch/arm/mach-imx/spl.c [*] as a
NON __weak function:
git grep -n "spl_boot_device" | grep weak
Shall I make this function [*] as __weak and provide override for it
in the board file?
The problem is in the call of spl_boot_mode() (which is overridden
already in arch/arm/mach-imx/spl.c) at common/spl/spl_mmc.c
Which then calls spl_boot_device() [**], which may return (correctly)
SPI-NOR for eMMC.
As is now spl_boot_device() is not a __weak function.
Why do you need to
force it in this way ?
The option is to use the proposed patch to make spl_boot_device as a
weak function.
The above text is a bit misleading - better version below.
The solution would be:
1. Use the proposed patch (with Kconfig option)
2. Define spl_boot_device as weak and override it in board file.
However, it is not the preferred solution as spl_boot_device() on my
setup correctly returns SPI-NOR (as SOC ROM loads SPL from SPI-NOR,
not eMMC).
Ok, but is a wek not thought for this purpose ? If it is weak, you can
change it and decide to return the device you want. You could also check
if Falco boot is enabled, at compile time with CONFIG_SPL_OS_BOOT or at
runtime with spl_start_uboot(). Should it not be enough ?
I am fine with a weak function only.
bye,
Heiko
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