linux-kernel - [PATCH v1] drm/ast: Fixed the casting issue reported by sparse

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Date:   Thu, 23 Jun 2022 16:31:16 +0800
From:   KuoHsiang Chou <kuohsiang_chou@...eedtech.com>
To:     <tzimmermann@...e.de>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>
CC:     <airlied@...hat.com>, <airlied@...ux.ie>, <daniel@...ll.ch>,
        <kuohsiang_chou@...eedtech.com>, <hungju_huang@...eedtech.com>,
        <luke_chen@...eedtech.com>, kernel test robot <lkp@...el.com>
Subject: [PATCH v1] drm/ast: Fixed the casting issue reported by sparse

V1:
1.Fixed sparse:cast truncates bits form constant value ()cast
  truncates bits from constant value (ffffffffffffff00 becomes 0)

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: KuoHsiang Chou <kuohsiang_chou@...eedtech.com>
---
 drivers/gpu/drm/ast/ast_dp.c  | 8 ++++----
 drivers/gpu/drm/ast/ast_drv.h | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
index f573d5824..2c71b8eef 100644
--- a/drivers/gpu/drm/ast/ast_dp.c
+++ b/drivers/gpu/drm/ast/ast_dp.c
@@ -34,7 +34,7 @@ int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata)
 		 * CRE4[7:0]: Read-Pointer for EDID (Unit: 4bytes); valid range: 0~64
 		 */
 		ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE4,
-					(u8) ~ASTDP_EDID_READ_POINTER_MASK, (u8) i);
+					ASTDP_AND_CLEAR_MASK, (u8) i);
 		j = 0;

 		/*
@@ -274,8 +274,8 @@ void ast_dp_set_mode(struct drm_crtc *crtc, struct ast_vbios_mode_info *vbios_mo
 	 * CRE1[7:0]: MISC1 (default: 0x00)
 	 * CRE2[7:0]: video format index (0x00 ~ 0x20 or 0x40 ~ 0x50)
 	 */
-	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE0, (u8) ~ASTDP_CLEAR_MASK,
+	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE0, ASTDP_AND_CLEAR_MASK,
 				ASTDP_MISC0_24bpp);
-	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE1, (u8) ~ASTDP_CLEAR_MASK, ASTDP_MISC1);
-	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE2, (u8) ~ASTDP_CLEAR_MASK, ModeIdx);
+	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE1, ASTDP_AND_CLEAR_MASK, ASTDP_MISC1);
+	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE2, ASTDP_AND_CLEAR_MASK, ModeIdx);
 }
diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
index a34db4380..2e44b971c 100644
--- a/drivers/gpu/drm/ast/ast_drv.h
+++ b/drivers/gpu/drm/ast/ast_drv.h
@@ -433,7 +433,7 @@ int ast_mode_config_init(struct ast_private *ast);
  */
 #define ASTDP_MISC0_24bpp			BIT(5)
 #define ASTDP_MISC1				0
-#define ASTDP_CLEAR_MASK			GENMASK(7, 0)
+#define ASTDP_AND_CLEAR_MASK		0x00

 /*
  * ASTDP resoultion table:

base-commit: ab3bfa333f25d26bb8bf414419f9a2e6a46a141f
--
2.27.0