On 10/21/25 21:50, Greg Kroah-Hartman wrote:
6.17-stable review patch. If anyone has any objections, please let me know.
From: Thomas Zimmermann tzimmermann@suse.de
commit 6f719373b943a955fee6fc2012aed207b65e2854 upstream.
Blank the display by disabling sync pulses with VGACR17<7>. Unblank by reenabling them. This VGA setting should be supported by all Aspeed hardware.
TWIMC, a regression report about 6.18-rc2 that was bisected to this commit just came in:
https://lore.kernel.org/all/a40caf8e-58ad-4f9c-af7f-54f6f69c29bb@googlemail....
To quote:
""" I have encountered a serious (for me) regression with 6.18-rc2 on my 2-socket Ivy Bridge Xeon E5-2697 v2 server. After booting, my console screen goes blank and stays blank. 6.18-rc1 was still fine.
[...]
When I revert this from 6.18-rc2, the issue goes away and my console screen works again. """
Ciao, Thorsten
Ast currently blanks via sync-off bits in VGACRB6. Not all BMCs handle VGACRB6 correctly. After disabling sync during a reboot, some BMCs do not reenable it after the soft reset. The display output remains dark. When the display is off during boot, some BMCs set the sync-off bits in VGACRB6, so the display remains dark. Observed with Blackbird AST2500 BMCs. Clearing the sync-off bits unconditionally fixes these issues.
Also do not modify VGASR1's SD bit for blanking, as it only disables GPU access to video memory.
v2:
- init vgacrb6 correctly (Jocelyn)
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: ce3d99c83495 ("drm: Call drm_atomic_helper_shutdown() at shutdown time for misc drivers") Tested-by: Nick Bowler nbowler@draconx.ca Reported-by: Nick Bowler nbowler@draconx.ca Closes: https://lore.kernel.org/dri-devel/wpwd7rit6t4mnu6kdqbtsnk5bhftgslio6e2jgkz6k... Cc: Douglas Anderson dianders@chromium.org Cc: Dave Airlie airlied@redhat.com Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Jocelyn Falempe jfalempe@redhat.com Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v6.7+ Reviewed-by: Jocelyn Falempe jfalempe@redhat.com Link: https://lore.kernel.org/r/20251014084743.18242-1-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
drivers/gpu/drm/ast/ast_mode.c | 18 ++++++++++-------- drivers/gpu/drm/ast/ast_reg.h | 1 + 2 files changed, 11 insertions(+), 8 deletions(-)
--- a/drivers/gpu/drm/ast/ast_mode.c +++ b/drivers/gpu/drm/ast/ast_mode.c @@ -836,22 +836,24 @@ ast_crtc_helper_atomic_flush(struct drm_ static void ast_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_state *state) { struct ast_device *ast = to_ast_device(crtc->dev);
- u8 vgacr17 = 0x00;
- u8 vgacrb6 = 0xff;
- ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xb6, 0xfc, 0x00);
- ast_set_index_reg_mask(ast, AST_IO_VGASRI, 0x01, 0xdf, 0x00);
- vgacr17 |= AST_IO_VGACR17_SYNC_ENABLE;
- vgacrb6 &= ~(AST_IO_VGACRB6_VSYNC_OFF | AST_IO_VGACRB6_HSYNC_OFF);
- ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0x17, 0x7f, vgacr17);
- ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xb6, 0xfc, vgacrb6);
} static void ast_crtc_helper_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_state *state) { struct drm_crtc_state *old_crtc_state = drm_atomic_get_old_crtc_state(state, crtc); struct ast_device *ast = to_ast_device(crtc->dev);
- u8 vgacrb6;
- u8 vgacr17 = 0xff;
- ast_set_index_reg_mask(ast, AST_IO_VGASRI, 0x01, 0xdf, AST_IO_VGASR1_SD);
- vgacrb6 = AST_IO_VGACRB6_VSYNC_OFF |
AST_IO_VGACRB6_HSYNC_OFF;- ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xb6, 0xfc, vgacrb6);
- vgacr17 &= ~AST_IO_VGACR17_SYNC_ENABLE;
- ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0x17, 0x7f, vgacr17);
/* * HW cursors require the underlying primary plane and CRTC to --- a/drivers/gpu/drm/ast/ast_reg.h +++ b/drivers/gpu/drm/ast/ast_reg.h @@ -29,6 +29,7 @@ #define AST_IO_VGAGRI (0x4E) #define AST_IO_VGACRI (0x54) +#define AST_IO_VGACR17_SYNC_ENABLE BIT(7) /* called "Hardware reset" in docs */ #define AST_IO_VGACR80_PASSWORD (0xa8) #define AST_IO_VGACR99_VGAMEM_RSRV_MASK GENMASK(1, 0) #define AST_IO_VGACRA1_VGAIO_DISABLED BIT(1)