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 <[email protected]>
Fixes: 2281475168d2 ("drm/ast: astdp: Perform link training during 
atomic_enable")
Cc: Thomas Zimmermann <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: [email protected]
Cc: <[email protected]> # 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

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