On Wed, Apr 12, 2023 at 11:55:34AM +0300, Tomi Valkeinen wrote:
> On 12/04/2023 11:50, Laurent Pinchart wrote:
> > Hi Tony,
> >
> > Thank you for the patch.
> >
> > On Wed, Apr 12, 2023 at 10:39:53AM +0300, Tony Lindgren wrote:
> >> We may not have dsi->dsidev initialized during probe, and that can
> >> lead into various dsi related warnings as omap_dsi_host_detach() gets
> >> called with dsi->dsidev set to NULL.
> >>
> >> The warnings can be "Fixed dependency cycle(s)" followed by a
> >> WARNING: CPU: 0 PID: 787 at drivers/gpu/drm/omapdrm/dss/dsi.c:4414.
> >
> > How can this happen ? I assume .detach() can't be called without a
> > priori successful call to .attach(), that that sets dsi->dsidev.
>
> I had a quick look, and the driver calls mipi_dsi_host_register() in
> probe, and mipi_dsi_host_unregister() in remove.
>
> mipi_dsi_host_unregister() always calls mipi_dsi_detach(), but I don't
> think mipi_dsi_host_register() always calls attach, which happens later
> when the peripheral probes.
Is this something that should be addressed in the DRM MIPI DSI helpers,
to only detach after an attach ?
> >> Let's fix the warnings by checking for a valid dsi->dsidev.
> >>
> >> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> >> ---
> >> drivers/gpu/drm/omapdrm/dss/dsi.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> >> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> >> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> >> @@ -4411,7 +4411,7 @@ static int omap_dsi_host_detach(struct mipi_dsi_host *host,
> >> {
> >> struct dsi_data *dsi = host_to_omap(host);
> >>
> >> - if (WARN_ON(dsi->dsidev != client))
> >> + if (dsi->dsidev && WARN_ON(dsi->dsidev != client))
> >> return -EINVAL;
> >>
> >> cancel_delayed_work_sync(&dsi->dsi_disable_work);
--
Regards,
Laurent Pinchart
