On 25/02/2022 18:05, Michal Wajdeczko wrote:
On 25.02.2022 18:18, Tvrtko Ursulin wrote:
On 25/02/2022 16:46, John Harrison wrote:
driver we don't care that much that we failed to load HWconfig and 'notice' is enough.
but I'm fine with all messages being drm_err (as we will not have to change that once again after HWconfig will be mandatory for the driver as well)
I would be against drm_err.
#define KERN_EMERG KERN_SOH "0" /* system is unusable */ #define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */ #define KERN_CRIT KERN_SOH "2" /* critical conditions */ #define KERN_ERR KERN_SOH "3" /* error conditions */ #define KERN_WARNING KERN_SOH "4" /* warning conditions */ #define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */ #define KERN_INFO KERN_SOH "6" /* informational */ #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
From the point of view of the kernel driver, this is not an error to its operation. It can at most be a warning, but notice is also fine by me. One could argue when reading "normal but significant condition" that it is not normal, when it is in fact unexpected, so if people prefer warning that is also okay by me. I still lean towards notice becuase of the hands-off nature i915 has with the pass-through of this blob.
From the point of view of the KMD, i915 will load and be 'functional' if it can't talk to the hardware at all. The UMDs won't work at all but
Well this reductio ad absurdum fails I think... :)
the driver load will be 'fine'. That's a requirement to be able to get the user to a software fallback desktop in order to work out why the hardware isn't working (e.g. no GuC firmware file). I would view this as similar. The KMD might have loaded but the UMDs are not functional. That is definitely an error condition to me.
... If GuC fails to load there is no command submission and driver will obviously log that with drm_err.
If blob fails to verify it depends on the userspace stack what will happen. As stated before on some platforms, and/or after a certain time, Mesa will not look at the blob at all. So i915 is fine (it is after all just a conduit for opaque data!), system overall is fine, so it definitely isn't a KERN_ERR level event.
>> + ERR_PTR(ret)); >> + >> ret = guc_enable_communication(guc); >> if (ret) >> goto err_log_capture; >> @@ -562,6 +567,8 @@ static void __uc_fini_hw(struct intel_uc *uc) >> if (intel_uc_uses_guc_submission(uc)) >> intel_guc_submission_disable(guc); >> + intel_guc_hwconfig_fini(&guc->hwconfig); >> + >> __uc_sanitize(uc); >> } >> diff --git a/drivers/gpu/drm/i915/i915_pci.c >> b/drivers/gpu/drm/i915/i915_pci.c >> index 76e590fcb903..1d31e35a5154 100644 >> --- a/drivers/gpu/drm/i915/i915_pci.c >> +++ b/drivers/gpu/drm/i915/i915_pci.c >> @@ -990,6 +990,7 @@ static const struct intel_device_info >> adl_p_info = { >> BIT(RCS0) | BIT(BCS0) | BIT(VECS0) | BIT(VCS0) | >> BIT(VCS2), >> .ppgtt_size = 48, >> .dma_mask_size = 39, >> + .has_guc_hwconfig = 1, > Who requested this change? It was previously done this way but the > instruction was that i915_pci.c is for hardware features only but > that > this, as you seem extremely keen about pointing out at every > opportunity, is a software feature.
This was requested by Michal as well. I definitely agree it is a software feature, but I was not aware that "i915_pci.c is for hardware features only".
Michal, do you agree with this and returning to the previous method for enabling the feature?
now I'm little confused as some arch direction was to treat FW as extension of the HW so for me it was natural to have 'has_guc_hwconfig' flag in device_info
if still for some reason it is undesired to mix HW and FW/SW flags inside single group of flags then maybe we should just add separate group of immutable flags where has_guc_hwconfig could be defined.
let our maintainers decide
Bah.. :)
And what was the previous method?
[comes back later]
Okay it was:
+static bool has_table(struct drm_i915_private *i915) +{ + if (IS_ALDERLAKE_P(i915)) + return true;
Which sucks a bit if we want to argue it does not belong in device info.
Why can't we ask the GuC if the blob exists? In fact what would happen if one would call __guc_action_get_hwconfig on any GuC platform?
That was how I originally wrote the code. However, other parties refuse to allow a H2G call to fail. The underlying CTB layers complain loudly on any CTB error. And the GuC architects insist that a call to query the table on an unsupported platform is an error and should return an 'unsupported' error code.
just for the background: IIRC the reason why arch didn't want 'query' mode that wont fail was that HWconfig is not optional on these selected platforms, so driver shall know up-front on which platforms it shall be working (and driver shall even fail if blob is not available)
Oh well, shrug, sounds silly but I will not pretend I am familiar with H2G
In this case has_table does sound better since it indeed isn't a hardware feature. It is a GuC fw thing and if we don't have a way to probe things there at runtime, then at least limit the knowledge to GuC files.
note that arch expectation is that driver itself shall be using this hwconfig (ie. will decode required data). while current approach is that driver acts only as a proxy to UMD, this has to change and refactoring will start (likely) soon. therefore flag has_guc_hwconfig fits better IMHO as this wont be just 'GuC' fw thing.
There we go, Jordan's validation gets a new unexpected use. :D
In this case it should maybe be like:
#define I915_NEEDS_GUC_HWCONFIG(i915) (IS_PLATFORM(xxx) || VER >= nnn)
Since it is still not a hardware feature like other device info flags.
Regards,
Tvrtko