Commit 1ce4c3ae authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

firmware: sysfb: Move bpp-depth calculation into screen_info helper 



Move the calculation of the bits per pixels for screen_info into a
helper function. This will make it available to other callers besides
the firmware code.

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250401094056.32904-14-tzimmermann@suse.de
parent e7f435b3

drivers/firmware/sysfb_simplefb.c

+1 −30
Original line number Diff line number Diff line
@@ -35,36 +35,7 @@ __init bool sysfb_parse_mode(const struct screen_info *si, 
	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 from the color bits, reserved bits and

	 * reported lfb_depth, whichever is highest.  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);

		bits_per_pixel = max_t(u32, bits_per_pixel, si->lfb_depth);

	} else {

		bits_per_pixel = si->lfb_depth;

	}

	bits_per_pixel = __screen_info_lfb_bits_per_pixel(si);



	for (i = 0; i < ARRAY_SIZE(formats); ++i) {

		const struct simplefb_format *f = &formats[i];

drivers/video/screen_info_generic.c

+36 −0
Original line number Diff line number Diff line
@@ -144,3 +144,39 @@ ssize_t screen_info_resources(const struct screen_info *si, struct resource *r, 
	return pos - r;

}

EXPORT_SYMBOL(screen_info_resources);



/*

 * 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 is not easily possible to fix this in struct screen_info,

 * as this could break UAPI. The best solution is to compute

 * bits_per_pixel from the color bits, reserved bits and

 * reported lfb_depth, whichever is highest.

 */



u32 __screen_info_lfb_bits_per_pixel(const struct screen_info *si)

{

	u32 bits_per_pixel = si->lfb_depth;



	if (bits_per_pixel > 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);

		bits_per_pixel = max_t(u32, bits_per_pixel, si->lfb_depth);

	}



	return bits_per_pixel;

}

EXPORT_SYMBOL(__screen_info_lfb_bits_per_pixel);

include/linux/screen_info.h

+2 −0
Original line number Diff line number Diff line
@@ -128,6 +128,8 @@ static inline unsigned int screen_info_video_type(const struct screen_info *si) 


ssize_t screen_info_resources(const struct screen_info *si, struct resource *r, size_t num);



u32 __screen_info_lfb_bits_per_pixel(const struct screen_info *si);



#if defined(CONFIG_PCI)

void screen_info_apply_fixups(void);

struct pci_dev *screen_info_pci_dev(const struct screen_info *si);