raspi/linux
1
0
Fork 1
mirror of https://github.com/raspberrypi/linux.git synced 2025-12-06 10:00:17 +00:00
Code Issues Projects Releases Wiki Activity

drm/ast: Clear preserved bits from register output value

Browse Source 
commit a9fb41b5de upstream.

Preserve the I/O register bits in __ast_write8_i_masked() as specified
by preserve_mask. Accidentally OR-ing the output value into these will
overwrite the register's previous settings.

Fixes display output on the AST2300, where the screen can go blank at
boot. The driver's original commit 312fec1405 ("drm: Initial KMS
driver for AST (ASpeed Technologies) 2000 series (v2)") already added
the broken code. Commit 6f719373b9 ("drm/ast: Blank with VGACR17 sync
enable, always clear VGACRB6 sync off") triggered the bug.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reported-by: Peter Schneider <pschneider1968@googlemail.com>
Closes: https://lore.kernel.org/dri-devel/a40caf8e-58ad-4f9c-af7f-54f6f69c29bb@googlemail.com/
Tested-by: Peter Schneider <pschneider1968@googlemail.com>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Fixes: 6f719373b9 ("drm/ast: Blank with VGACR17 sync enable, always clear VGACRB6 sync off")
Fixes: 312fec1405 ("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Nick Bowler <nbowler@draconx.ca>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v3.5+
Link: https://patch.msgid.link/20251024073626.129032-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Zimmermann
2025-10-24 09:35:53 +02:00
committed by Greg Kroah-Hartman
parent 0142fe8959
commit aeb1cf1e8d
1 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/gpu/drm/ast/ast_drv.h
View File

@@ -286,13 +286,13 @@ static inline void __ast_write8_i(void __iomem *addr, u32 reg, u8 index, u8 val)
__ast_write8(addr, reg + 1, val);
}
static inline void __ast_write8_i_masked(void __iomem *addr, u32 reg, u8 index, u8 read_mask,
static inline void __ast_write8_i_masked(void __iomem *addr, u32 reg, u8 index, u8 preserve_mask,
u8 val)
{
u8 tmp = __ast_read8_i_masked(addr, reg, index, read_mask);
u8 tmp = __ast_read8_i_masked(addr, reg, index, preserve_mask);
tmp |= val;
__ast_write8_i(addr, reg, index, tmp);
val &= ~preserve_mask;
__ast_write8_i(addr, reg, index, tmp | val);
}
static inline u32 ast_read32(struct ast_device *ast, u32 reg)