[Intel-gfx] [PATCH] drm/i915: Rate limit 'Fault errors' message

[Stefan Fritsch]

I think we should do both. Any log message that can be triggered 50 
times per second in practice should be rate limited. Also, the rate 
limiting is probably a candidate for backporting to stable kernels while 
the real fix may be not.

PS: See also my other mail about "drm/i915: Detecting Vt-d when running 
as guest os"

On 19.10.20 08:43, Joonas Lahtinen wrote:
> + Zhenyu & Zhi,
> 
> Should not we instead fix the reason why the errors happen instead of
> rate-limiting them?
> 
> Regards, Joonas
> 
> Quoting Stefan Fritsch (2020-10-16 18:23:40)
>> If linux is running as a guest and the host is doing igd pass-through
>> with VT-d enabled, this message is logged dozens of times per second.
>>
>> Cc: stable at vger.kernel.org
>> Signed-off-by: Stefan Fritsch <sf at sfritsch.de>
>> ---
>>
>> The i915 driver should also detect VT-d in this case, but that is a
>> different issue.  I have sent a separate mail with subject 'Detecting
>> Vt-d when running as guest os'.
>>
>>
>>   drivers/gpu/drm/i915/i915_irq.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>> index 759f523c6a6b..29096634e697 100644
>> --- a/drivers/gpu/drm/i915/i915_irq.c
>> +++ b/drivers/gpu/drm/i915/i915_irq.c
>> @@ -2337,7 +2337,7 @@ gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
>>   
>>                  fault_errors = iir & gen8_de_pipe_fault_mask(dev_priv);
>>                  if (fault_errors)
>> -                       drm_err(&dev_priv->drm,
>> +                       drm_err_ratelimited(&dev_priv->drm,
>>                                  "Fault errors on pipe %c: 0x%08x\n",
>>                                  pipe_name(pipe),
>>                                  fault_errors);
>> -- 
>> 2.28.0
>>