Hi Am 16.07.21 um 11:55 schrieb [email protected]:
From: "Ainux.Wang" <[email protected]>There is should a status when do not get edid.
Well, not really.So, the problem is that VGA is not hotplug-able. It's supposed to be connected when the computer gets switched on. And there's no interface for sensing the connection state.
But in practice, the cable can be attached/detached at any time. Reading out the EDID is the non-official way for detecting the connection state. You either get EDID data or garbage, where the latter is interpreted as 'disconnected'.
But really old monitors (maybe mid-90s and before) don't provide EDID data. For those, DRM adds standard VGA modes IIRC. And they would likely be detected as 'disconnected'.
I'll merge your original patch '(r <= 0)' and anyone who's stuck with such an old monitor can probably specify a compatible EDID on the kernel command line.
(I'd like to hear other people's opinion about this TBH.) Best regards Thomas
Signed-off-by: Ainux.Wang <[email protected]> --- drivers/gpu/drm/ast/ast_mode.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c index e5996ae03c49..05df48b3d223 100644 --- a/drivers/gpu/drm/ast/ast_mode.c +++ b/drivers/gpu/drm/ast/ast_mode.c @@ -1231,8 +1231,10 @@ static int ast_get_modes(struct drm_connector *connector) ret = drm_add_edid_modes(connector, edid); kfree(edid); return ret; - } else + } else { drm_connector_update_edid_property(&ast_connector->base, NULL); + return -ENXIO; + } return 0; }
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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