linux-kernel - [PATCH 4.4 26/36] drm/ast: Fix test for VGA enabled

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Message-Id: <20170313083354.095600188@linuxfoundation.org>
Date:   Mon, 13 Mar 2017 16:39:26 +0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "Y.C. Chen" <yc_chen@...eedtech.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Joel Stanley <joel@....id.au>, Dave Airlie <airlied@...hat.com>
Subject: [PATCH 4.4 26/36] drm/ast: Fix test for VGA enabled

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Y.C. Chen <yc_chen@...eedtech.com>

commit 905f21a49d388de3e99438235f3301cabf0c0ef4 upstream.

The test to see if VGA was already enabled is doing an unnecessary
second test from a register that may or may not have been initialized
to a valid value. Remove it.

Signed-off-by: Y.C. Chen <yc_chen@...eedtech.com>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Acked-by: Joel Stanley <joel@....id.au>
Tested-by: Y.C. Chen <yc_chen@...eedtech.com>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/ast/ast_post.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/drivers/gpu/drm/ast/ast_post.c
+++ b/drivers/gpu/drm/ast/ast_post.c
@@ -58,13 +58,9 @@ bool ast_is_vga_enabled(struct drm_devic
 		/* TODO 1180 */
 	} else {
 		ch = ast_io_read8(ast, AST_IO_VGA_ENABLE_PORT);
-		if (ch) {
-			ast_open_key(ast);
-			ch = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb6, 0xff);
-			return ch & 0x04;
-		}
+		return !!(ch & 0x01);
 	}
-	return 0;
+	return false;
 }

 static const u8 extreginfo[] = { 0x0f, 0x04, 0x1c, 0xff };