linux/drivers/firmware/sysfb_simplefb.c
Thomas Zimmermann f35cd3fa77 firmware/sysfb: Fix EFI/VESA format selection
Select color format for EFI/VESA firmware scanout buffer from the
number of bits per pixel and the position of the individual color
components. Fixes the selected format for the buffer in several odd
cases. For example, XRGB1555 has been reported as ARGB1555 because
of the different use of depth and transparency in VESA and Linux.

Bits-per-pixel is always the pixel's raw number of bits; including
alpha and filler bits. It is preferred over color depth, which has a
different meaning among various components and standards.

Also do not compare reserved bits and transparency bits to each other.
These values have different meanings, as reserved bits include filler
bits while transparency does not.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230102112927.26565-2-tzimmermann@suse.de
2023-01-03 14:23:03 +01:00

165 lines
4.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic System Framebuffers
* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
*/
/*
* simple-framebuffer probing
* Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
* If the mode is incompatible, we return "false" and let the caller create
* legacy nodes instead.
*/
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/screen_info.h>
#include <linux/sysfb.h>
static const char simplefb_resname[] = "BOOTFB";
static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
/* try parsing screen_info into a simple-framebuffer mode struct */
__init bool sysfb_parse_mode(const struct screen_info *si,
struct simplefb_platform_data *mode)
{
__u8 type;
u32 bits_per_pixel;
unsigned int i;
type = si->orig_video_isVGA;
if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
return false;
/*
* The meaning of depth and bpp for direct-color formats is
* inconsistent:
*
* - DRM format info specifies depth as the number of color
* bits; including alpha, but not including filler bits.
* - Linux' EFI platform code computes lfb_depth from the
* individual color channels, including the reserved bits.
* - VBE 1.1 defines lfb_depth for XRGB1555 as 16, but later
* versions use 15.
* - On the kernel command line, 'bpp' of 32 is usually
* XRGB8888 including the filler bits, but 15 is XRGB1555
* not including the filler bit.
*
* It's not easily possible to fix this in struct screen_info,
* as this could break UAPI. The best solution is to compute
* bits_per_pixel here and ignore lfb_depth. In the loop below,
* ignore simplefb formats with alpha bits, as EFI and VESA
* don't specify alpha channels.
*/
if (si->lfb_depth > 8) {
bits_per_pixel = max(max3(si->red_size + si->red_pos,
si->green_size + si->green_pos,
si->blue_size + si->blue_pos),
si->rsvd_size + si->rsvd_pos);
} else {
bits_per_pixel = si->lfb_depth;
}
for (i = 0; i < ARRAY_SIZE(formats); ++i) {
const struct simplefb_format *f = &formats[i];
if (f->transp.length)
continue; /* transparent formats are unsupported by VESA/EFI */
if (bits_per_pixel == f->bits_per_pixel &&
si->red_size == f->red.length &&
si->red_pos == f->red.offset &&
si->green_size == f->green.length &&
si->green_pos == f->green.offset &&
si->blue_size == f->blue.length &&
si->blue_pos == f->blue.offset) {
mode->format = f->name;
mode->width = si->lfb_width;
mode->height = si->lfb_height;
mode->stride = si->lfb_linelength;
return true;
}
}
return false;
}
__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
const struct simplefb_platform_data *mode)
{
struct platform_device *pd;
struct resource res;
u64 base, size;
u32 length;
int ret;
/*
* If the 64BIT_BASE capability is set, ext_lfb_base will contain the
* upper half of the base address. Assemble the address, then make sure
* it is valid and we can actually access it.
*/
base = si->lfb_base;
if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
base |= (u64)si->ext_lfb_base << 32;
if (!base || (u64)(resource_size_t)base != base) {
printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
return ERR_PTR(-EINVAL);
}
/*
* Don't use lfb_size as IORESOURCE size, since it may contain the
* entire VMEM, and thus require huge mappings. Use just the part we
* need, that is, the part where the framebuffer is located. But verify
* that it does not exceed the advertised VMEM.
* Note that in case of VBE, the lfb_size is shifted by 16 bits for
* historical reasons.
*/
size = si->lfb_size;
if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
size <<= 16;
length = mode->height * mode->stride;
if (length > size) {
printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
return ERR_PTR(-EINVAL);
}
length = PAGE_ALIGN(length);
/* setup IORESOURCE_MEM as framebuffer memory */
memset(&res, 0, sizeof(res));
res.flags = IORESOURCE_MEM;
res.name = simplefb_resname;
res.start = base;
res.end = res.start + length - 1;
if (res.end <= res.start)
return ERR_PTR(-EINVAL);
pd = platform_device_alloc("simple-framebuffer", 0);
if (!pd)
return ERR_PTR(-ENOMEM);
sysfb_apply_efi_quirks(pd);
ret = platform_device_add_resources(pd, &res, 1);
if (ret)
goto err_put_device;
ret = platform_device_add_data(pd, mode, sizeof(*mode));
if (ret)
goto err_put_device;
ret = platform_device_add(pd);
if (ret)
goto err_put_device;
return pd;
err_put_device:
platform_device_put(pd);
return ERR_PTR(ret);
}