[U-Boot] Cannot boot mx6qsabred with 2019.07-rc2

[Fabio Estevam]

Hi Peng,

On Thu, May 16, 2019 at 11:29 PM Peng Fan <peng.fan at nxp.com> wrote:

> You could enable DEBUG in SPL, and disable SPL_SDP because of size will exceeds.
> Then see what happends.
> I have no idea, then. My board is REV C4, chip 1.5

My mx6qsabresd is revC2, with a i.MX6Q rev 1.2 populated.

After further investigation we can confirm that the problem is caused
by SPL size being greater than the 68kB limit (4KB header + 64KB max
size)as explained in include/configs/imx6_spl.h:

---------------
#ifndef __IMX6_SPL_CONFIG_H
#define __IMX6_SPL_CONFIG_H

#ifdef CONFIG_SPL
/*
 * see Figure 8-3 in IMX6DQ/IMX6SDL Reference manuals:
 *  - IMX6SDL OCRAM (IRAM) is from 0x00907000 to 0x0091FFFF
 *  - IMX6DQ has 2x IRAM of IMX6SDL but we intend to support IMX6SDL as well
 *  - BOOT ROM stack is at 0x0091FFB8
 *  - if icache/dcache is enabled (eFuse/strapping controlled) then the
 *    IMX BOOT ROM will setup MMU table at 0x00918000, therefore we need to
 *    fit between 0x00907000 and 0x00918000.
 *  - Additionally the BOOT ROM loads what they consider the firmware image
 *    which consists of a 4K header in front of us that contains the IVT, DCD
 *    and some padding thus 'our' max size is really 0x00908000 - 0x00918000
 *    or 64KB
 */
#define CONFIG_SPL_MAX_SIZE             0x10000
#define CONFIG_SPL_STACK                0x0091FFB8
/*
 * Pad SPL to 68KB (4KB header + 64KB max size). This allows to write the
 * SPL/U-Boot combination generated with u-boot-with-spl.imx directly to a
 * boot media (given that boot media specific offset is configured properly).
 */
#define CONFIG_SPL_PAD_TO               0x11000
---------------

Here are the tests I ran:

Test 1: Original U-Boot 2019.07-rc2
-----------------------------------------------

SPL: 76800 (75 kB)
Result: does not boot

Test 2: Removing extra dtbs
-------------------------------------

--- a/configs/mx6sabresd_defconfig
+++ b/configs/mx6sabresd_defconfig
@@ -59,10 +59,10 @@ CONFIG_EFI_PARTITION=y
 CONFIG_OF_CONTROL=y
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="imx6q-sabresd"
-CONFIG_OF_LIST="imx6q-sabresd imx6qp-sabresd imx6dl-sabresd"
+CONFIG_OF_LIST="imx6q-sabresd"
 CONFIG_MULTI_DTB_FIT=y
 CONFIG_SPL_MULTI_DTB_FIT=y
-CONFIG_SPL_OF_LIST="imx6dl-sabresd imx6q-sabresd imx6qp-sabresd"
+CONFIG_SPL_OF_LIST="imx6q-sabresd"
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_SPL_DM=y

SPL:68608 (67 kB)
Result: boots correctly

Test 3: Removing SPL_DM
------------------------------------

--- a/configs/mx6sabresd_defconfig
+++ b/configs/mx6sabresd_defconfig
@@ -65,7 +65,6 @@ CONFIG_SPL_MULTI_DTB_FIT=y
 CONFIG_SPL_OF_LIST="imx6dl-sabresd imx6q-sabresd imx6qp-sabresd"
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
-CONFIG_SPL_DM=y
 CONFIG_USB_FUNCTION_FASTBOOT=y
 CONFIG_FASTBOOT_BUF_ADDR=0x12000000
 CONFIG_FASTBOOT_BUF_SIZE=0x10000000

SPL: 68608 (67 kB)
Result: boots correctly

I will send a v2 removing CONFIG_SPL_DM.

Also, the SPL size check should be really done after the multi fit
image is concatenated so that we can have a chance to detect such size
overflow in build time.

Thanks