On 04/08/2020 15:13, Tomi Valkeinen wrote:
> On 28/07/2020 21:14, Aaro Koskinen wrote:
>> Hi,
>>
>> Looks like N900 display support has broken after v5.6.
>>
>> When using v5.7, or the current mainline (v5.8-rc7), the boot hangs at:
>>
>> [ 6.269500] omapdss_dss 48050000.dss: 48050000.dss supply vdda_video not found, using dummy regulator
>> [ 6.321685] DSS: OMAP DSS rev 2.0
>> [ 6.328002] omapdss_dss 48050000.dss: bound 48050400.dispc (ops dispc_component_ops)
>> [ 6.336364] omapdss_dss 48050000.dss: bound 48050c00.encoder (ops venc_component_ops)
>> [ 6.345153] omapdrm omapdrm.0: DMM not available, disable DMM support
>> [ 6.352447] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>>
>> with a blank display.
>>
>> I tried to bisect this, and the first commit that breaks the display is:
>>
>> 2f004792adadcf017fde50339b432a26039fff0c is the first bad commit
>> commit 2f004792adadcf017fde50339b432a26039fff0c
>> Author: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>> Date: Wed Feb 26 13:24:57 2020 +0200
>>
>> drm/omap: venc: Register a drm_bridge
>>
>> This commit does not yet hang the kernel, but the display is blank and
>> the probe fails:
>>
>> [ 6.290100] omapdss_dss 48050000.dss: 48050000.dss supply vdda_video not foun
>> d, using dummy regulator
>> [ 6.342346] DSS: OMAP DSS rev 2.0
>> [ 6.348663] omapdss_dss 48050000.dss: bound 48050400.dispc (ops dispc_component_ops)
>> [ 6.357025] omapdss_dss 48050000.dss: bound 48050c00.encoder (ops venc_component_ops)
>> [ 6.365814] omapdrm omapdrm.0: DMM not available, disable DMM support
>> [ 6.372863] omapdrm omapdrm.0: omap_modeset_init failed: ret=-22
>> [ 6.414611] omapdrm: probe of omapdrm.0 failed with error -22
>
> Afaics, this is caused by the patch doing
>
> if (!venc->output.next_bridge)
>
> instead of
>
> if (venc->output.next_bridge)
>
> Fixing that removes the error on beagle xm, but for some reason I don't see TV-out as a DRM output
> (but HDMI output works).
>
>> The hang seems to start with this commit:
>>
>> commit 8bef8a6d5da81b909a190822b96805a47348146f (HEAD -> master)
>> Author: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>> Date: Wed Feb 26 13:25:10 2020 +0200
>>
>> drm/omap: sdi: Register a drm_bridge
>>
>> Confusingly, some of the commits between these two commits do provide a
>> working display, e.g. 13d2d52f59c0c79398d9c9e2ea3d661a0e5b6bbc ("drm/omap:
>> sdi: Sort includes alphabetically") works...
>
> The venc issue is fixed in "Switch the HDMI and VENC outputs to drm_bridge", which is a few commits
> after the "venc: Register a drm_bridge".
>
> So I'm guessing SDI works until "sdi: Register a drm_bridge", but as omapdrm doesn't probe, you get
> no displays.
>
> Can you try to pinpoint a bit where the hang happens? Maybe add DRM/omapdrm debug prints, or perhaps
> sysrq works and it shows a lock that's in deadlock.
Also, one data point would be to disable venc, e.g. set venc status to "disabled" in dts.
Tomi
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