Commit 1b617bc9 authored by Pierre Asselin's avatar Pierre Asselin Committed by Thomas Zimmermann
Browse files

firmware/sysfb: Fix VESA format selection 



Some legacy BIOSes report no reserved bits in their 32-bit rgb mode,
breaking the calculation of bits_per_pixel in  commit f35cd3fa
("firmware/sysfb: Fix EFI/VESA format selection").  However they report
lfb_depth correctly for those modes.  Keep the computation but
set bits_per_pixel to lfb_depth if the latter is larger.

v2 fixes the warnings from a max3() macro with arguments of different
types;  split the bits_per_pixel assignment to avoid uglyfing the code
with too many typecasts.

v3 fixes space and formatting blips pointed out by Javier, and change
the bit_per_pixel assignment back to a single statement using two casts.

v4 go back to v2 and use max_t()

Signed-off-by: default avatarPierre Asselin <pa@panix.com>
Fixes: f35cd3fa ("firmware/sysfb: Fix EFI/VESA format selection")
Link: https://lore.kernel.org/r/4Psm6B6Lqkz1QXM@panix3.panix.com
Link: https://lore.kernel.org/r/20230412150225.3757223-1-javierm@redhat.com


Tested-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230419044834.10816-1-pa@panix.com
parent c8687694

drivers/firmware/sysfb_simplefb.c

+3 −1
Original line number Diff line number Diff line
@@ -51,7 +51,8 @@ __init bool sysfb_parse_mode(const struct screen_info *si, 
	 *

	 * 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,

	 * 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.

	 */
@@ -60,6 +61,7 @@ __init bool sysfb_parse_mode(const struct screen_info *si, 
					  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;

	}