Messages in this thread | | | Date | Thu, 14 Jan 2021 09:13:28 -0800 | From | khsieh@codeauro ... | Subject | Re: [PATCH 1/2] drm/msm/dp: postpone irq_hpd event during connection pending state |
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On 2021-01-13 16:00, Stephen Boyd wrote: > Quoting khsieh@codeaurora.org (2021-01-13 15:44:32) >> On 2021-01-13 12:22, Stephen Boyd wrote: >> > Quoting khsieh@codeaurora.org (2021-01-13 09:44:24) >> >> On 2021-01-11 11:55, Stephen Boyd wrote: >> >> > Quoting Kuogee Hsieh (2021-01-07 12:30:24) >> >> >> irq_hpd event can only be executed at connected state. Therefore >> >> >> irq_hpd event should be postponed if it happened at connection >> >> >> pending state. This patch also make sure both link rate and lane >> >> > >> >> > Why does it happen at connection pending state? >> >> plug in need two state to complete it. >> >> advance to connection pending state once link training completed and >> >> sent uevent notification to frame work. >> >> transition to connected state after frame work provided resolution >> >> timing and start transmit video panel. >> >> Therefore irq_hpd should not be handled if it occurred before >> >> connected >> >> state. >> > >> > Sure that's what's going on in the patch but you didn't answer my >> > question. Why does irq_hpd happen before connected state? >> >> I have no idea why it happen this way. >> during debug >> https://partnerissuetracker.corp.google.com/issues/170598152 >> I saw two different scenario >> 1) irq_hpd followed by unplug with less than 20 ms in between. this >> one >> fixed by this patch set. >> 2) plug followed by irq_hpd around 300ms in between. it does not cause >> problem. but it should be handled in order (after connected state). > > Ok. So nobody understands why the hardware is acting this way and we're > papering over the problem by forcing the HPD state to be what we think > it should be? That's not great.
irq_hpd is issued from dongle. it then go through EC ps8805 driver and reach DP driver finally. Again, to duplicate problem #1 this at my set up, i have to intentionally wiggling type-c connector of dongle. But I can not duplicate problem #2 and only saw it one time from Quantan provide logs.
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