[PATCH v2] drm/ast: Fix ast_dp connection status

[Jocelyn Falempe]

ast_dp_is_connected() used to also check for link training success
to report the DP connector as connected. Without this check, the
physical_status is always connected. So if no monitor is present, it
will fail to read the EDID and set the default resolution to 640x480
instead of 1024x768.

Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
Fixes: 2281475168d2 ("drm/ast: astdp: Perform link training during atomic_enable")
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Dave Airlie <airlied at redhat.com>
Cc: dri-devel at lists.freedesktop.org
Cc: <stable at vger.kernel.org> # v6.12+
---
 drivers/gpu/drm/ast/ast_dp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
index 0e282b7b167c..30aad5c0112a 100644
--- a/drivers/gpu/drm/ast/ast_dp.c
+++ b/drivers/gpu/drm/ast/ast_dp.c
@@ -17,6 +17,12 @@ static bool ast_astdp_is_connected(struct ast_device *ast)
 {
 	if (!ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xDF, AST_IO_VGACRDF_HPD))
 		return false;
+	/*
+	 * HPD might be set even if no monitor is connected, so also check that
+	 * the link training was successful.
+	 */
+	if (!ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xDC, AST_IO_VGACRDC_LINK_SUCCESS))
+		return false;
 	return true;
 }
 

base-commit: 798047e63ac970f105c49c22e6d44df901c486b2
-- 
2.47.1