"Pandiyan, Dhinakaran" <dhinakaran.pandiyan@xxxxxxxxx> writes:
> On Tue, 2018-02-13 at 15:26 -0800, Rodrigo Vivi wrote:
>> From: Andy Lutomirski <luto@xxxxxxxxxx>
>>
>> The current PSR code has a two call sites that each schedule delayed
>> work to activate PSR. As far as I can tell, each call site intends
>> to keep PSR inactive for the given amount of time and then allow it
>> to be activated.
>>
>> The call sites are:
>>
>> - intel_psr_enable(), which explicitly states in a comment that
>> it's trying to keep PSR off a short time after the dispay is
>> initialized as a workaround.
>>
>> - intel_psr_flush(). There isn't an explcit explanation, but the
>> intent is presumably to keep PSR off until the display has been
>> idle for 100ms.
>>
>> The current code doesn't actually accomplish either of these goals.
>> Rather than keeping PSR inactive for the given amount of time, it
>> will schedule PSR for activation after the given time, with the
>> earliest target time in such a request winning.
>>
>> In other words, if intel_psr_enable() is immediately followed by
>> intel_psr_flush(), then PSR will be activated after 100ms even if
>> intel_psr_enable() wanted a longer delay. And, if the screen is
>> being constantly updated so that intel_psr_flush() is called once
>> per frame at 60Hz, PSR will still be activated once every 100ms.
>>
>> Rewrite the code so that it does what was intended. This adds
>> a new function intel_psr_schedule(), which will enable PSR after
>> the requested time but no sooner.
>>
>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
>> Tested-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>> Acked-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>>
>> ---
>> drivers/gpu/drm/i915/i915_debugfs.c | 8 +++--
>> drivers/gpu/drm/i915/i915_drv.h | 3 +-
>> drivers/gpu/drm/i915/intel_psr.c | 66 ++++++++++++++++++++++++++++++++-----
>> 3 files changed, 66 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
>> index 960302668649..da80ee16a3cf 100644
>> --- a/drivers/gpu/drm/i915/i915_debugfs.c
>> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
>> @@ -2521,8 +2521,12 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
>> seq_printf(m, "Active: %s\n", yesno(dev_priv->psr.active));
>> seq_printf(m, "Busy frontbuffer bits: 0x%03x\n",
>> dev_priv->psr.busy_frontbuffer_bits);
>> - seq_printf(m, "Re-enable work scheduled: %s\n",
>> - yesno(work_busy(&dev_priv->psr.work.work)));
>> +
>> + if (timer_pending(&dev_priv->psr.activate_timer))
>> + seq_printf(m, "Activate scheduled: yes, in %dms\n",
>> + jiffies_to_msecs(dev_priv->psr.activate_timer.expires - jiffies));
>> + else
>> + seq_printf(m, "Activate scheduled: no\n");
>>
>> if (HAS_DDI(dev_priv)) {
>> if (dev_priv->psr.psr2_support)
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index c06d4126c447..2afa5c05a79b 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -762,7 +762,8 @@ struct i915_psr {
>> bool sink_support;
>> struct intel_dp *enabled;
>> bool active;
>> - struct delayed_work work;
>> + struct timer_list activate_timer;
>> + struct work_struct activate_work;
>> unsigned busy_frontbuffer_bits;
>> bool psr2_support;
>> bool aux_frame_sync;
>> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
>> index 2ef374f936b9..826b480841ac 100644
>> --- a/drivers/gpu/drm/i915/intel_psr.c
>> +++ b/drivers/gpu/drm/i915/intel_psr.c
>> @@ -450,6 +450,28 @@ static void intel_psr_activate(struct intel_dp *intel_dp)
>> dev_priv->psr.active = true;
>> }
>>
>> +static void intel_psr_schedule(struct drm_i915_private *i915,
>> + unsigned long min_wait_ms)
>> +{
>> + unsigned long next;
>> +
>> + lockdep_assert_held(&i915->psr.lock);
>> +
>> + /*
>> + * We update next enable and call mod_timer() because it's
>> + * possible that intel_psr_wrk() has already been called and is
>> + * waiting for psr.lock. If that's the case, we don't want it
>> + * to immediately enable PSR.
>> + *
>> + * We also need to make sure that PSR is never activated earlier
>> + * than requested to avoid breaking intel_psr_enable()'s workaround
>> + * for pre-gen9 hardware.
>> + */
>> + next = jiffies + msecs_to_jiffies(min_wait_ms);
>> + if (time_after(next, i915->psr.activate_timer.expires))
>
> .expires is an internal member, does not seem like a good idea to read
> it outside of the exported interfaces.
Chris I believe this question is for you.
I just ignored for a while because I thought it was for Andy,
but now I saw that you modified the original patch on exactly this point.
Btw I believe this is a modification that should had been clear
highlighted when you sent and with your Signed-off-by.
So, could you please explain and give the sign-off here?
Or should we rebase original Andy's version without this change?
Thanks,
Rodrigo.
>
>
> -DK
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