Do not set CR1B[6] when programming the pitch. The bit effects VGA text mode and is not interpreted by qemu. [1] It has no affect on the scanline pitch.
The scanline bit that is set into CR1B[6] belongs into CR13[7], which the driver sets up correctly. This bug goes back to the driver's initial commit. Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de> Acked-by: Gerd Hoffmann <kra...@redhat.com> Link: https://gitlab.com/qemu-project/qemu/-/blob/stable-9.2/hw/display/cirrus_vga.c?ref_type=heads#L1112 # 1 Fixes: f9aa76a85248 ("drm/kms: driver for virtual cirrus under qemu") Cc: Adam Jackson <a...@redhat.com> Cc: Dave Airlie <airl...@redhat.com> Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com> Cc: Maxime Ripard <mrip...@kernel.org> Cc: Thomas Zimmermann <tzimmerm...@suse.de> Cc: <sta...@vger.kernel.org> # v3.5+ --- drivers/gpu/drm/tiny/cirrus-qemu.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/gpu/drm/tiny/cirrus-qemu.c b/drivers/gpu/drm/tiny/cirrus-qemu.c index 52ec1e4ea9e51..a00d3b7ded6c5 100644 --- a/drivers/gpu/drm/tiny/cirrus-qemu.c +++ b/drivers/gpu/drm/tiny/cirrus-qemu.c @@ -318,7 +318,6 @@ static void cirrus_pitch_set(struct cirrus_device *cirrus, unsigned int pitch) /* Enable extended blanking and pitch bits, and enable full memory */ cr1b = 0x22; cr1b |= (pitch >> 7) & 0x10; - cr1b |= (pitch >> 6) & 0x40; wreg_crt(cirrus, 0x1b, cr1b); cirrus_set_start_address(cirrus, 0); -- 2.48.1
