> -----Original Message----- > From: Nikula, Jani <jani.nikula@xxxxxxxxx> > Sent: Thursday, December 15, 2022 4:00 PM > To: Murthy, Arun R <arun.r.murthy@xxxxxxxxx>; intel- > gfx@xxxxxxxxxxxxxxxxxxxxx; ville.syrjala@xxxxxxxxxxxxxxx; Deak, Imre > <imre.deak@xxxxxxxxx> > Cc: Murthy, Arun R <arun.r.murthy@xxxxxxxxx> > Subject: Re: [PATCHv6] drm/i915/dp: change aux_ctl reg read to polling read > > On Thu, 15 Dec 2022, Arun R Murthy <arun.r.murthy@xxxxxxxxx> wrote: > > 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 | 15 +++++---------- > > 1 file changed, 5 insertions(+), 10 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..dec88f41380e 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > > @@ -40,21 +40,16 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp) > > struct drm_i915_private *i915 = dp_to_i915(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)); > > + u32 status, 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) > > What's wrong with this comparison? Although it probably does work by > coincidence. > If (ret) dev_err(); Will also work, but for code readability using -ETIMEDOUT(sorry missed the declaration int ret;) Thanks and Regards, Arun R Murthy -------------------- > BR, > Jani. > > > > 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; > > } > > -- > Jani Nikula, Intel Open Source Graphics Center
