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efi/gop: Allow specifying mode by <xres>x<yres>

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Add the ability to choose a video mode using a command-line argument of
the form
	video=efifb:<xres>x<yres>

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200320020028.1936003-13-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Arvind Sankar 2020-03-19 22:00:26 -04:00 committed by Ard Biesheuvel
parent fffb68047e
commit d9ff0323d0
2 changed files with 88 additions and 1 deletions
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5
Documentation/fb/efifb.rst
View File

@ -50,4 +50,9 @@ mode=n
The EFI stub will set the mode of the display to mode number n if
possible.
<xres>x<yres>
The EFI stub will search for a display mode that matches the specified
horizontal and vertical resolution, and set the mode of the display to
it if one is found.
Edgar Hucek <gimli@dark-green.com>

84
drivers/firmware/efi/libstub/gop.c
View File

@ -6,6 +6,7 @@
* ----------------------------------------------------------------------- */
#include <linux/bitops.h>
#include <linux/ctype.h>
#include <linux/efi.h>
#include <linux/screen_info.h>
#include <linux/string.h>
@ -17,11 +18,17 @@
enum efi_cmdline_option {
EFI_CMDLINE_NONE,
EFI_CMDLINE_MODE_NUM,
EFI_CMDLINE_RES
};
static struct {
enum efi_cmdline_option option;
u32 mode;
union {
u32 mode;
struct {
u32 width, height;
} res;
};
} cmdline __efistub_global = { .option = EFI_CMDLINE_NONE };
static bool parse_modenum(char *option, char **next)
@ -41,11 +48,33 @@ static bool parse_modenum(char *option, char **next)
return true;
}
static bool parse_res(char *option, char **next)
{
u32 w, h;
if (!isdigit(*option))
return false;
w = simple_strtoull(option, &option, 10);
if (*option++ != 'x' || !isdigit(*option))
return false;
h = simple_strtoull(option, &option, 10);
if (*option && *option++ != ',')
return false;
cmdline.option = EFI_CMDLINE_RES;
cmdline.res.width = w;
cmdline.res.height = h;
*next = option;
return true;
}
void efi_parse_option_graphics(char *option)
{
while (*option) {
if (parse_modenum(option, &option))
continue;
if (parse_res(option, &option))
continue;
while (*option && *option++ != ',')
;
@ -94,6 +123,56 @@ static u32 choose_mode_modenum(efi_graphics_output_protocol_t *gop)
return cmdline.mode;
}
static u32 choose_mode_res(efi_graphics_output_protocol_t *gop)
{
efi_status_t status;
efi_graphics_output_protocol_mode_t *mode;
efi_graphics_output_mode_info_t *info;
unsigned long info_size;
u32 max_mode, cur_mode;
int pf;
u32 m, w, h;
mode = efi_table_attr(gop, mode);
cur_mode = efi_table_attr(mode, mode);
info = efi_table_attr(mode, info);
w = info->horizontal_resolution;
h = info->vertical_resolution;
if (w == cmdline.res.width && h == cmdline.res.height)
return cur_mode;
max_mode = efi_table_attr(mode, max_mode);
for (m = 0; m < max_mode; m++) {
if (m == cur_mode)
continue;
status = efi_call_proto(gop, query_mode, m,
&info_size, &info);
if (status != EFI_SUCCESS)
continue;
pf = info->pixel_format;
w = info->horizontal_resolution;
h = info->vertical_resolution;
efi_bs_call(free_pool, info);
if (pf == PIXEL_BLT_ONLY || pf >= PIXEL_FORMAT_MAX)
continue;
if (w == cmdline.res.width && h == cmdline.res.height)
return m;
}
efi_printk("Couldn't find requested mode\n");
return cur_mode;
}
static void set_mode(efi_graphics_output_protocol_t *gop)
{
efi_graphics_output_protocol_mode_t *mode;
@ -103,6 +182,9 @@ static void set_mode(efi_graphics_output_protocol_t *gop)
case EFI_CMDLINE_MODE_NUM:
new_mode = choose_mode_modenum(gop);
break;
case EFI_CMDLINE_RES:
new_mode = choose_mode_res(gop);
break;
default:
return;
}