| Message ID | 1312233275-10843-1-git-send-email-jbarnes@virtuousgeek.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 1 Aug 2011 14:14:35 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote: > + for (try = 0; try < 3; try++) { > + status = I915_READ(ch_ctl); > + if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0) > + break; > + msleep(1); > + } > + > + if (try == 10) { 10 != 3
On Mon, 01 Aug 2011 14:42:25 -0700 Keith Packard <keithp@keithp.com> wrote: > On Mon, 1 Aug 2011 14:14:35 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote: > > > + for (try = 0; try < 3; try++) { > > + status = I915_READ(ch_ctl); > > + if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0) > > + break; > > + msleep(1); > > + } > > + > > + if (try == 10) { > > 10 != 3 Oh well that will make the backtrace silent, won't it...
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 4493641..de570ce 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -315,9 +315,17 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, else precharge = 5; - if (I915_READ(ch_ctl) & DP_AUX_CH_CTL_SEND_BUSY) { - DRM_ERROR("dp_aux_ch not started status 0x%08x\n", - I915_READ(ch_ctl)); + /* Try to wait for any previous AUX channel activity */ + for (try = 0; try < 3; try++) { + status = I915_READ(ch_ctl); + if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0) + break; + msleep(1); + } + + if (try == 10) { + WARN(1, "dp_aux_ch not started status 0x%08x\n", + I915_READ(ch_ctl)); return -EBUSY; }
Before initiating a new read or write on the DP AUX channel, wait for any outstanding activity to complete. This may happen during normal retry behavior. If the wait fails (i.e. after 1ms the AUX channel is still busy) dump a backtrace to make the caller easier to spot. v2: use msleep instead, and timeout after 3ms (only ever saw 1 retry with msleep in testing) Fixes https://bugs.freedesktop.org/show_bug.cgi?id=38136. Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org> --- drivers/gpu/drm/i915/intel_dp.c | 14 +++++++++++--- 1 files changed, 11 insertions(+), 3 deletions(-)