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. > > 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? Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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