Re: [PATCH v3 1/4] drm/i915: Always do WOPCM partitioning based on real firmware sizes

[Yaodong Li <yaodong.li@intel.com>]

On 04/13/2018 07:15 PM, Michal Wajdeczko wrote:
> On Tue, 10 Apr 2018 02:42:17 +0200, Jackie Li <yaodong.li@intel.com> 
> wrote:
>
>> After enabled the WOPCM write-once registers locking status checking,
>> reloading of the i915 module will fail with modparam enable_guc set to 3
>> (enable GuC and HuC firmware loading) if the module was originally 
>> loaded
>> with enable_guc set to 1 (only enable GuC firmware loading).
>
> Is this frequent and required scenario ? or just for debug/development ?
>
My understanding is this should be a nice to have feature and mainly for 
debugging.
>> This is
>> because WOPCM registers were updated and locked without considering 
>> the HuC
>> FW size. Since we need both GuC and HuC FW sizes to determine the final
>> layout of WOPCM, we should always calculate the WOPCM layout based on 
>> the
>> actual sizes of the GuC and HuC firmware available for a specific 
>> platform
>> if we need continue to support enable/disable HuC FW loading dynamically
>> with enable_guc modparam.
>>
>> This patch splits uC firmware fetching into two stages. First stage 
>> is to
>> fetch the firmware image and verify the firmware header. uC firmware 
>> will
>> be marked as verified and this will make FW info available for following
>> WOPCM layout calculation. The second stage is to create a GEM object and
>> copy the FW data into the created GEM object which will only be 
>> available
>> when GuC/HuC loading is enabled by enable_guc modparam. This will 
>> guarantee
>> that the WOPCM layout will be always be calculated correctly without 
>> making
>> any assumptions to the GuC and HuC firmware sizes.
>
> You are also assuming that on reload exactly the same GuC/HuC firmwares
> will bee used as in initial run. This will make this useless for debug/
> development scenarios, where custom fw are likely to be specified.
>
This patch is mainly for providing a real fix to support 
enable_guc=1->3->1 use case.
It based on the fact that it is inevitable that sometimes we need to 
reboot the system
if the status of the fw was changed on the file system.
I am not sure how often we switch between different HuC FW with 
different sizes?
> If we want to support enable_guc=1->3->1 scenarios for debug/dev then
> maybe more flexible will be other approach that makes allocations from
> the other end as proposed in [1]
>
> [1] https://patchwork.freedesktop.org/patch/212471/
Actually, I do think this might be one of the options, and I've also put 
some comments on this
series. The main concern I have is it still make assumption on the GuC 
FW size and may
run into the same issue if the GuC FW failed to meet the requirement.
and for debugging purpose it would have the same possible for different 
GuC FW debugging.
>
>>
>> v3:
>>  - Rebase
>>
>> Signed-off-by: Jackie Li <yaodong.li@intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
>> Cc: Michal Winiarski <michal.winiarski@intel.com>
>> Cc: John Spotswood <john.a.spotswood@intel.com>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_uc.c    | 14 ++++----------
>>  drivers/gpu/drm/i915/intel_uc_fw.c | 31 ++++++++++++++++++++-----------
>>  drivers/gpu/drm/i915/intel_uc_fw.h |  7 +++++--
>>  3 files changed, 29 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_uc.c 
>> b/drivers/gpu/drm/i915/intel_uc.c
>> index 1cffaf7..73b8f6c 100644
>> --- a/drivers/gpu/drm/i915/intel_uc.c
>> +++ b/drivers/gpu/drm/i915/intel_uc.c
>> @@ -172,11 +172,8 @@ void intel_uc_init_early(struct drm_i915_private 
>> *i915)
>>     sanitize_options_early(i915);
>> -    if (USES_GUC(i915))
>> -        intel_uc_fw_fetch(i915, &guc->fw);
>> -
>> -    if (USES_HUC(i915))
>> -        intel_uc_fw_fetch(i915, &huc->fw);
>> +    intel_uc_fw_fetch(i915, &guc->fw, USES_GUC(i915));
>> +    intel_uc_fw_fetch(i915, &huc->fw, USES_HUC(i915));
>
> Hmm, side effect of those unconditional fetches might be unwanted 
> warnings
> about missing firmwares (on configs with disabled guc) as well as 
> extended
> driver load time.
Hmm, if HAS_GUC is false then fw path would be NULL. The fetch will 
return directly.
>
> Do we really need to support this corner case enable_guc=1->3 at all 
> costs?
I think this is the real solution for this issue (with no assumption). 
However, we do
need to decide whether we should support such a corner case which is 
mainly for
debugging.
>
> /michal
>
>>  }
>> void intel_uc_cleanup_early(struct drm_i915_private *i915)
>> @@ -184,11 +181,8 @@ void intel_uc_cleanup_early(struct 
>> drm_i915_private *i915)
>>      struct intel_guc *guc = &i915->guc;
>>      struct intel_huc *huc = &i915->huc;
>> -    if (USES_HUC(i915))
>> -        intel_uc_fw_fini(&huc->fw);
>> -
>> -    if (USES_GUC(i915))
>> -        intel_uc_fw_fini(&guc->fw);
>> +    intel_uc_fw_fini(&huc->fw);
>> +    intel_uc_fw_fini(&guc->fw);
>>     guc_free_load_err_log(guc);
>>  }
>> diff --git a/drivers/gpu/drm/i915/intel_uc_fw.c 
>> b/drivers/gpu/drm/i915/intel_uc_fw.c
>> index 6e8e0b5..a9cb900 100644
>> --- a/drivers/gpu/drm/i915/intel_uc_fw.c
>> +++ b/drivers/gpu/drm/i915/intel_uc_fw.c
>> @@ -33,11 +33,13 @@
>>   *
>>   * @dev_priv: device private
>>   * @uc_fw: uC firmware
>> + * @copy_to_obj: whether fetch uC firmware into GEM object or not
>
> s/copy_to_obj/fetch
sure.
>
>>   *
>> - * Fetch uC firmware into GEM obj.
>> + * Fetch and verify uC firmware and copy firmware data into GEM 
>> object if
>> + * @copy_to_obj is true.
>>   */
>>  void intel_uc_fw_fetch(struct drm_i915_private *dev_priv,
>> -               struct intel_uc_fw *uc_fw)
>> +               struct intel_uc_fw *uc_fw, bool copy_to_obj)
>>  {
>>      struct pci_dev *pdev = dev_priv->drm.pdev;
>>      struct drm_i915_gem_object *obj;
>> @@ -154,17 +156,24 @@ void intel_uc_fw_fetch(struct drm_i915_private 
>> *dev_priv,
>>          goto fail;
>>      }
>> -    obj = i915_gem_object_create_from_data(dev_priv, fw->data, 
>> fw->size);
>> -    if (IS_ERR(obj)) {
>> -        err = PTR_ERR(obj);
>> -        DRM_DEBUG_DRIVER("%s fw object_create err=%d\n",
>> -                 intel_uc_fw_type_repr(uc_fw->type), err);
>> -        goto fail;
>> +    uc_fw->size = fw->size;
>> +    uc_fw->fetch_status = INTEL_UC_FIRMWARE_VERIFIED;
>> +
>> +    if (copy_to_obj) {
>> +        obj = i915_gem_object_create_from_data(dev_priv, fw->data,
>> +                               fw->size);
>> +        if (IS_ERR(obj)) {
>> +            err = PTR_ERR(obj);
>> +            DRM_DEBUG_DRIVER("%s fw object_create err=%d\n",
>> +                     intel_uc_fw_type_repr(uc_fw->type),
>> +                     err);
>> +            goto fail;
>> +        }
>> +
>> +        uc_fw->obj = obj;
>> +        uc_fw->fetch_status = INTEL_UC_FIRMWARE_SUCCESS;
>>      }
>> -    uc_fw->obj = obj;
>> -    uc_fw->size = fw->size;
>> -    uc_fw->fetch_status = INTEL_UC_FIRMWARE_SUCCESS;
>>      DRM_DEBUG_DRIVER("%s fw fetch %s\n",
>>               intel_uc_fw_type_repr(uc_fw->type),
>>               intel_uc_fw_status_repr(uc_fw->fetch_status));
>> diff --git a/drivers/gpu/drm/i915/intel_uc_fw.h 
>> b/drivers/gpu/drm/i915/intel_uc_fw.h
>> index dc33b12..4e7ecc8 100644
>> --- a/drivers/gpu/drm/i915/intel_uc_fw.h
>> +++ b/drivers/gpu/drm/i915/intel_uc_fw.h
>> @@ -36,6 +36,7 @@ enum intel_uc_fw_status {
>>      INTEL_UC_FIRMWARE_FAIL = -1,
>>      INTEL_UC_FIRMWARE_NONE = 0,
>>      INTEL_UC_FIRMWARE_PENDING,
>> +    INTEL_UC_FIRMWARE_VERIFIED,
>>      INTEL_UC_FIRMWARE_SUCCESS
>>  };
>> @@ -84,6 +85,8 @@ const char *intel_uc_fw_status_repr(enum 
>> intel_uc_fw_status status)
>>          return "NONE";
>>      case INTEL_UC_FIRMWARE_PENDING:
>>          return "PENDING";
>> +    case INTEL_UC_FIRMWARE_VERIFIED:
>> +        return "VERIFIED";
>>      case INTEL_UC_FIRMWARE_SUCCESS:
>>          return "SUCCESS";
>>      }
>> @@ -131,14 +134,14 @@ static inline void intel_uc_fw_sanitize(struct 
>> intel_uc_fw *uc_fw)
>>   */
>>  static inline u32 intel_uc_fw_get_upload_size(struct intel_uc_fw 
>> *uc_fw)
>>  {
>> -    if (uc_fw->fetch_status != INTEL_UC_FIRMWARE_SUCCESS)
>> +    if (uc_fw->fetch_status < INTEL_UC_FIRMWARE_VERIFIED)
>>          return 0;
>>     return uc_fw->header_size + uc_fw->ucode_size;
>>  }
>> void intel_uc_fw_fetch(struct drm_i915_private *dev_priv,
>> -               struct intel_uc_fw *uc_fw);
>> +               struct intel_uc_fw *uc_fw, bool copy_to_obj);
>>  int intel_uc_fw_upload(struct intel_uc_fw *uc_fw,
>>                 int (*xfer)(struct intel_uc_fw *uc_fw,
>>                     struct i915_vma *vma));

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