From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31CEF4086A; Tue, 11 Nov 2025 00:55:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762822539; cv=none; b=F96YbrYtLoLDxblmra2Pjqg5X1ghxMd1AYSyjOHqgyksO+f8HxEyh/bxxmMPVza7BTuevQImy23o+ltIznK/V4/LFA0bTxvYD1nvxwcAH+NLuwkM4FVJOfS5y2H+s98syu4fgE8v6i0A2zU3mgklMw31UYXBSvqsD2l9IVbpefA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762822539; c=relaxed/simple; bh=mLAbZWt94PTOtXEifTefyp2iBHzy6ZaQlw4nH2UfIu0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dheFPslYUw0uXfh4pkwbd52xXlApv/A31oQ8OsegsGtQocNjtEEjzHPJcs/EqjhoeWs9vGC1isymik6fFq0vjlPgpI55/GDC74yrZU7j9h1hBI6h3YSfXjQwPbhy2gVQ5hjCXPlNtVDZM8Sw7O8bqcQEt7tIlfPpmkGtjBcr8cA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fq4rwBXX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fq4rwBXX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA258C16AAE; Tue, 11 Nov 2025 00:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762822539; bh=mLAbZWt94PTOtXEifTefyp2iBHzy6ZaQlw4nH2UfIu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fq4rwBXXOzy5dYN6xbkRAHehiILWv6pjO9aFk8u5tl1OXU/Br84rj4/kOzoIBJJGV WMkj2gni2Rbl7p6Rcmw1DLiAbcKhUcKBaVS5nXW4NrKZ8m8rw67VTIK+GX2zCFe7bL QXnzvbkdzjhBtzI31gXGFXC9B/n5Y+qdnZjGmjhg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Thomas Zimmermann , Peter Schneider , Jocelyn Falempe , Nick Bowler , Douglas Anderson , Dave Airlie , dri-devel@lists.freedesktop.org Subject: [PATCH 6.12 070/565] drm/ast: Clear preserved bits from register output value Date: Tue, 11 Nov 2025 09:38:46 +0900 Message-ID: <20251111004528.526435608@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004526.816196597@linuxfoundation.org> References: <20251111004526.816196597@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Zimmermann commit a9fb41b5def8e1e0103d5fd1453787993587281e 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 312fec1405dd ("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)") already added the broken code. Commit 6f719373b943 ("drm/ast: Blank with VGACR17 sync enable, always clear VGACRB6 sync off") triggered the bug. Signed-off-by: Thomas Zimmermann Reported-by: Peter Schneider Closes: https://lore.kernel.org/dri-devel/a40caf8e-58ad-4f9c-af7f-54f6f69c29bb@googlemail.com/ Tested-by: Peter Schneider Reviewed-by: Jocelyn Falempe Fixes: 6f719373b943 ("drm/ast: Blank with VGACR17 sync enable, always clear VGACRB6 sync off") Fixes: 312fec1405dd ("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)") Cc: Thomas Zimmermann Cc: Nick Bowler Cc: Douglas Anderson Cc: Dave Airlie Cc: Jocelyn Falempe Cc: dri-devel@lists.freedesktop.org Cc: # v3.5+ Link: https://patch.msgid.link/20251024073626.129032-1-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/ast/ast_drv.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/ast/ast_drv.h +++ b/drivers/gpu/drm/ast/ast_drv.h @@ -286,13 +286,13 @@ static inline void __ast_write8_i(void _ __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)