drm/ast: Fix ast_dp connection status

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@redhat.com>
Fixes: 2281475168d2 ("drm/ast: astdp: Perform link training during atomic_enable")
Reported-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Tested-by: Jose Lopez <jose.lopez@hpe.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.12+
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20250124141142.2434138-1-jfalempe@redhat.com

diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
index 0e282b7b167c6b09116e6079d2842f6336213732..30aad5c0112a155576c860fb2a64c2e631420f21 100644 (file)
--- 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;
 }