12.07.2019 11:10, Maxime Ripard пишет: > On Thu, Jul 11, 2019 at 06:55:03PM +0300, Dmitry Osipenko wrote: >> 11.07.2019 12:03, Maxime Ripard пишет: >>> On Wed, Jul 10, 2019 at 06:05:18PM +0300, Dmitry Osipenko wrote: >>>> 10.07.2019 17:05, Maxime Ripard пишет: >>>>> On Wed, Jul 10, 2019 at 04:29:19PM +0300, Dmitry Osipenko wrote: >>>>>> This works: >>>>>> >>>>>> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c >>>>>> index 56d36779d213..e5a2f9c8f404 100644 >>>>>> --- a/drivers/gpu/drm/drm_client_modeset.c >>>>>> +++ b/drivers/gpu/drm/drm_client_modeset.c >>>>>> @@ -182,6 +182,8 @@ drm_connector_pick_cmdline_mode(struct drm_connector *connector) >>>>>> mode = drm_mode_create_from_cmdline_mode(connector->dev, cmdline_mode); >>>>>> if (mode) >>>>>> list_add(&mode->head, &connector->modes); >>>>>> + else >>>>>> + cmdline_mode->specified = false; >>>>> >>>>> Hmmm, it's not clear to me why that wouldn't be the case. >>>>> >>>>> If we come back to the beginning of that function, we retrieve the >>>>> cmdline_mode buffer from the connector pointer, that will probably >>>>> have been parsed a first time using drm_mode_create_from_cmdline_mode >>>>> in drm_helper_probe_add_cmdline_mode. >>>>> >>>>> Now, I'm guessing that the issue is that in >>>>> drm_mode_parse_command_line_for_connector, if we have a named mode, we >>>>> just copy the mode over and set mode->specified. >>>>> >>>>> And we then move over to do other checks, and that's probably what >>>>> fails and returns, but our drm_cmdline_mode will have been modified. >>>>> >>>>> I'm not entirely sure how to deal with that though. >>>>> >>>>> I guess we could allocate a drm_cmdline_mode structure on the stack, >>>>> fill that, and if successful copy over its content to the one in >>>>> drm_connector. That would allow us to only change the content on >>>>> success, which is what I would expect from such a function? >>>>> >>>>> How does that sound? >>>> >>>> I now see that there is DRM_MODE_TYPE_USERDEF flag that is assigned only >>>> for the "cmdline" mode and drm_client_rotation() is the only place in >>>> DRM code that cares about whether mode is from cmdline, hence looks like >>>> it will be more correct to do the following: >>> >>> I'm still under the impression that we're dealing with workarounds of >>> a more central issue, which is that we shouldn't return a partially >>> modified drm_cmdline_mode. >>> >>> You said it yourself, the breakage is in the commit changing the >>> command line parsing logic, while you're fixing here some code that >>> was introduced later on. >> >> The problem stems from assumption that *any* named mode is valid. It >> looks to me that the ultimate solution would be to move the mode's name >> comparison into the [1], if that's possible. >> >> [1] drm_mode_parse_command_line_for_connector() > > Well, one could argue that video=tegrafb is invalid and should be > rejected as well, but we haven't cleared that up. The video=tegrafb is invalid mode, there is nothing to argue here. And the problem is that invalid modes and not rejected for the very beginning. >>> Can you try the followintg patch? >>> http://code.bulix.org/8cwk4c-794565?raw >> >> This doesn't help because the problem with the rotation_reflection is >> that it's 0 if "rotation" not present in the cmdline and then ilog2(0) >> returns -1. So the patch "drm/modes: Don't apply cmdline's rotation if >> it wasn't specified" should be correct in any case. > > So we would have the same issue with rotate=0 then? No, we won't. Rotation mode is parsed into the DRM_MODE bitmask and rotate=0 corresponds to DRM_MODE_ROTATE_0, which is BIT(0) as you may notice. Hence rotation_reflection=0 is always an invalid value, meaning that "rotate" option does not present in the cmdline. Please consult the code, in particular see drm_mode_parse_cmdline_options() which was written by yourself ;)
