6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Zimmermann tzimmermann@suse.de
commit 4bfb389a0136a13f0802eeb5e97a0e76d88f77ae upstream.
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 tzimmermann@suse.de Acked-by: Gerd Hoffmann kraxel@redhat.com Link: https://gitlab.com/qemu-project/qemu/-/blob/stable-9.2/hw/display/cirrus_vga... # 1 Fixes: f9aa76a85248 ("drm/kms: driver for virtual cirrus under qemu") Cc: Adam Jackson ajax@redhat.com Cc: Dave Airlie airlied@redhat.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard mripard@kernel.org Cc: Thomas Zimmermann tzimmermann@suse.de Cc: stable@vger.kernel.org # v3.5+ Link: https://lore.kernel.org/r/20250328091821.195061-2-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/tiny/cirrus-qemu.c | 1 - 1 file changed, 1 deletion(-)
--- 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 cirr /* 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);