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() > 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.
