Commit c0880485 authored by Nikita Kiryanov's avatar Nikita Kiryanov Committed by Tom Rini

lcd: implement a callback for splashimage

On some architectures certain values of splashimage will lead to
a data abort exception.

Document the problem, and implement a callback for splashimage to
reject such values.

Cc: Anatolij Gustschin <agust@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Signed-off-by: 's avatarNikita Kiryanov <nikita@compulab.co.il>
Acked-by: 's avatarIgor Grinberg <grinberg@compulab.co.il>
parent 48ec5291
......@@ -1530,6 +1530,17 @@ CBFS (Coreboot Filesystem) support
allows for a "silent" boot where a splash screen is
loaded very quickly after power-on.
CONFIG_SPLASHIMAGE_GUARD
If this option is set, then U-Boot will prevent the environment
variable "splashimage" from being set to a problematic address
(see README.displaying-bmps and README.arm-unaligned-accesses).
This option is useful for targets where, due to alignment
restrictions, an improperly aligned BMP image will cause a data
abort. If you think you will not have problems with unaligned
accesses (for example because your toolchain prevents them)
there is no need to set this option.
CONFIG_SPLASH_SCREEN_ALIGN
If this option is set the splash image can be freely positioned
......
......@@ -33,6 +33,8 @@
#include <common.h>
#include <command.h>
#include <stdarg.h>
#include <search.h>
#include <env_callback.h>
#include <linux/types.h>
#include <stdio_dev.h>
#if defined(CONFIG_POST)
......@@ -1099,6 +1101,30 @@ static void *lcd_logo(void)
#endif /* CONFIG_LCD_LOGO && !CONFIG_LCD_INFO_BELOW_LOGO */
}
#ifdef CONFIG_SPLASHIMAGE_GUARD
static int on_splashimage(const char *name, const char *value, enum env_op op,
int flags)
{
ulong addr;
int aligned;
if (op == env_op_delete)
return 0;
addr = simple_strtoul(value, NULL, 16);
/* See README.displaying-bmps */
aligned = (addr % 4 == 2);
if (!aligned) {
printf("Invalid splashimage value. Value must be 16 bit aligned, but not 32 bit aligned\n");
return -1;
}
return 0;
}
U_BOOT_ENV_CALLBACK(splashimage, on_splashimage);
#endif
void lcd_position_cursor(unsigned col, unsigned row)
{
console_col = min(col, CONSOLE_COLS - 1);
......
If you are experiencing hangups/data-aborts when trying to display a BMP image,
the following might be relevant to your situation...
Some architectures cannot handle unaligned memory accesses, and an attempt to
perform one will lead to a data abort. On such architectures it is necessary to
make sure all data is properly aligned, and in many situations simply choosing
a 32 bit aligned address is enough to ensure proper alignment. This is not
always the case when dealing with data that has an internal layout such as a
BMP image:
BMP images have a header that starts with 2 byte-size fields followed by mostly
32 bit fields. The packed struct that represents this header can be seen below:
typedef struct bmp_header {
/* Header */
char signature[2];
__u32 file_size;
__u32 reserved;
__u32 data_offset;
... etc
} __attribute__ ((packed)) bmp_header_t;
When placed in an aligned address such as 0x80a00000, char signature offsets
the __u32 fields into unaligned addresses (in our example 0x80a00002,
0x80a00006, and so on...). When these fields are accessed by U-Boot, a 32 bit
access is generated at a non-32-bit-aligned address, causing a data abort.
The proper alignment for BMP images is therefore: 32-bit-aligned-address + 2.
......@@ -41,6 +41,12 @@
#define SILENT_CALLBACK
#endif
#ifdef CONFIG_SPLASHIMAGE_GUARD
#define SPLASHIMAGE_CALLBACK "splashimage:splashimage,"
#else
#define SPLASHIMAGE_CALLBACK
#endif
/*
* This list of callback bindings is static, but may be overridden by defining
* a new association in the ".callbacks" environment variable.
......@@ -51,6 +57,7 @@
"bootfile:bootfile," \
"loadaddr:loadaddr," \
SILENT_CALLBACK \
SPLASHIMAGE_CALLBACK \
"stdin:console,stdout:console,stderr:console," \
CONFIG_ENV_CALLBACK_LIST_STATIC
......
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