On bochs DRM driver, the execution of "setterm --blank force" results
in a frozen screen instead of a blank screen. It's due to the lack of
the screen blanking support in its code.
Actually, the QEMU bochs vga side can switch to the blanking mode when
the bit 0x20 is cleared on VGA_ATT_IW register (0x3c0), which updates
ar_index in QEMU side. So, essentially, we'd just need to clear the
bit at pipe disable callback; that's what this patch does essentially.
However, a tricky part is that the access via VGA_ATT_IW is done in
"flip-flop"; the first write is for index and the second write is for
the data like palette. Meanwhile, in the current bochs DRM driver,
the flip-flop wasn't considered, and it calls only the register update
once with the value 0x20.
The spec and the actual VGA implementation in QEMU suggests that the
flip flop flag is discarded by reading the CRTC index register
(VGA_IS1_RC, 0x3da). So, in this patch, we add the helper to read a
byte and the call to clear the flip flop flag before changing the
blank / unblank setup via VGA_ATT_IW register.
v1->v2:
* discard ar_flip_flop by reading 0x3da, add bochs_vga_readb()
* include video/vga.h for VGA register definitions
* move the blank/unblank code to bochs_hw_blank()
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210421080859.14869-1-tiwai@suse.de
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Recently (qemu 2.2+) the qemu stdvga got a register to switch the vga
framebuffer endianness. This patch adds code to explicitly set the
endianness of the framebuffer. In most cases this has no effect as
the default is guest architecture endianness. It is needed though in
case a architecture supports both big and little endian, i.e. for
ppc64le.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
DRM driver for (virtual) vga cards using the bochs dispi
interface, such as the qemu standard vga (qemu -vga std).
Don't bother supporting anything but 32bpp for now, even
though the virtual hardware is able to do that.
Known issue: mmap(/dev/fb0) doesn't work.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
