Re: [Intel-gfx] [PATCH] drm/i915/uc: Extra info notice about FW version mis-match vs overrides

[John Harrison <John.C.Harrison@Intel.com>]

On 11/21/2019 02:43, Michal Wajdeczko wrote:
> On Thu, 21 Nov 2019 01:27:23 +0100, <John.C.Harrison@intel.com> wrote:
>
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> If a FW override is present then a version mis-match is actually
>> ignored. The warning message was still being printed, though. Which
>
> It wasn't a "warning", just "notice"
>
>> could confuse people by implying that the load had failed due to the
>> mis-match when actually something else had failed.
>
> The mis-match still might be a reason why something else failed.
> If there is possible confusing, it's likely due to lack of or incomplete
> message from this other failure point. So we should make sure that all
> failure points correctly indicate the failure reason to avoid confusing.
> Do you recall what this other confusing failure was?

Sorry, bad commit message comment. The point was that you could 
successfully load the GuC FW but then something entirely unrelated fails 
(with or without appropriate error message). However, the first apparent 
failure in dmesg is the GuC version mis-match. Therefore a user (or even 
developer) might assume that all subsequent issues are caused by the FW 
mismatch causing the GuC to not load at all and hence not investigate 
any later messages until this first one is fixed/understood.

So the point is just to avoid people wasting time investigating 
something that is not actually an error.


>
>>
>> This patch adds an extra message to say that the mis-match is being
>> ignored if an override is present.
>>
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>  drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c 
>> b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
>> index 66a30ab7044a..c1ae807b07ae 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
>> @@ -361,6 +361,9 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw, 
>> struct drm_i915_private *i915)
>>              err = -ENOEXEC;
>>              goto fail;
>>          }
>> +
>> +        dev_notice(dev, "%s firmware %s: Firmware override so 
>> ignoring version mis-match\n",
>> +               intel_uc_fw_type_repr(uc_fw->type), uc_fw->path);
>
> If you still want to include clear statement about mis-match being 
> ignored,
> then maybe instead of adding new message it could be combined with old 
> one:
>
Or maybe just move the mis-match notice into the 'goto fail' section and 
not print anything at all in the case of an override. On the grounds 
that if someone is specifying an override then it is almost certainly 
because the default version is not what they want. So yes, it obviously 
is going to be mis-match.


> if (uc_fw->major_ver_found != uc_fw->major_ver_wanted ||
>             uc_fw->minor_ver_found < uc_fw->minor_ver_wanted) {
> -               dev_notice(dev, "%s firmware %s: unexpected version: 
> %u.%u != %u.%u\n",
> +               dev_notice(dev, "%s firmware %s: %s: %u.%u != %u.%u\n",
>                            intel_uc_fw_type_repr(uc_fw->type), 
> uc_fw->path,
> +                          intel_uc_fw_is_overridden(uc_fw) ?
> +                          "ignoring unexpected version" : "wrong 
> version",
>                            uc_fw->major_ver_found, 
> uc_fw->minor_ver_found,
>                            uc_fw->major_ver_wanted, 
> uc_fw->minor_ver_wanted);
>                 if (!intel_uc_fw_is_overridden(uc_fw)) {
>
> Michal

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