On Mon, 19 Dec 2022, "Murthy, Arun R" <arun.r.murthy@xxxxxxxxx> wrote: > Any comments? >From #intel-gfx: <vsyrjala> bashing the hw for 500 usec seems a bit harsh Which is true. The default for intel_de_wait_for_register() is 2 us. Should probably stick to that. BR, Jani. > > Thanks and Regards, > Arun R Murthy > -------------------- > >> -----Original Message----- >> From: Murthy, Arun R <arun.r.murthy@xxxxxxxxx> >> Sent: Thursday, December 15, 2022 4:44 PM >> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; ville.syrjala@xxxxxxxxxxxxxxx; Nikula, Jani >> <jani.nikula@xxxxxxxxx>; Deak, Imre <imre.deak@xxxxxxxxx> >> Cc: Murthy, Arun R <arun.r.murthy@xxxxxxxxx> >> Subject: [PATCHv6] drm/i915/dp: change aux_ctl reg read to polling read >> >> The busy timeout logic checks for the AUX BUSY, then waits for the timeout >> period and then after timeout reads the register for BUSY or Success. >> Instead replace interrupt with polling so as to read the AUX CTL register often >> before the timeout period. Looks like there might be some issue with >> interrupt-on-read. Hence changing the logic to polling read. >> >> v2: replace interrupt with polling read >> v3: use usleep_rang instead of msleep, updated commit msg >> v4: use intel_wait_for_regiter internal function >> v5: use __intel_de_wait_for_register with 500us slow and 10ms fast timeout >> v6: check return value of __intel_de_wait_for_register >> >> Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx> >> --- >> drivers/gpu/drm/i915/display/intel_dp_aux.c | 14 +++++--------- >> 1 file changed, 5 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c >> b/drivers/gpu/drm/i915/display/intel_dp_aux.c >> index 91c93c93e5fc..973dadecf712 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c >> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c >> @@ -41,20 +41,16 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp) >> i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp); >> const unsigned int timeout_ms = 10; >> u32 status; >> - bool done; >> - >> -#define C (((status = intel_de_read_notrace(i915, ch_ctl)) & >> DP_AUX_CH_CTL_SEND_BUSY) == 0) >> - done = wait_event_timeout(i915->display.gmbus.wait_queue, C, >> - msecs_to_jiffies_timeout(timeout_ms)); >> + int ret; >> >> - /* just trace the final value */ >> - trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true); >> + ret = __intel_de_wait_for_register(i915, ch_ctl, >> + DP_AUX_CH_CTL_SEND_BUSY, 0, >> + 500, timeout_ms, &status); >> >> - if (!done) >> + if (ret == -ETIMEDOUT) >> drm_err(&i915->drm, >> "%s: did not complete or timeout within %ums >> (status 0x%08x)\n", >> intel_dp->aux.name, timeout_ms, status); -#undef C >> >> return status; >> } >> -- >> 2.25.1 > -- Jani Nikula, Intel Open Source Graphics Center
