Quoting Jackie Li (2018-03-14 02:32:53)
> GuC WOPCM registers are write-once registers. Current driver code accesses
> these registers without checking the accessibility to these registers which
> will lead to unpredictable driver behaviors if these registers were touch
> by other components (such as faulty BIOS code).
>
> This patch moves the GuC WOPCM registers updating code into intel_wopcm.c
> and adds check before and after the update to GuC WOPCM registers so that
> we can make sure the driver is in a known state after writing to these
> write-once registers.
>
> v6:
> - Made sure module reloading won't bug the kernel while doing
> locking status checking
>
> v7:
> - Fixed patch format issues
>
> v8:
> - Fixed coding style issue on register lock bit macro definition (Sagar)
>
> v9:
> - Avoided to use redundant !! to cast uint to bool (Chris)
> - Return error code instead of GEM_BUG_ON for locked with invalid register
> values case (Sagar)
> - Updated guc_wopcm_hw_init to use guc_wopcm as first parameter (Michal)
> - Added code to set and validate the HuC_LOADING_AGENT_GUC bit in GuC
> WOPCM offset register based on the presence of HuC firmware (Michal)
> - Use bit fields instead of macros for GuC WOPCM flags (Michal)
>
> v10:
> - Refined variable names, removed redundant comments (Joonas)
> - Introduced lockable_reg to handle the write once register write and
> propagate the write error to caller (Joonas)
> - Used lockable_reg abstraction to avoid locking bit check on generic
> i915_reg_t (Michal)
> - Added log message for error paths (Michal)
> - Removed hw_updated flag and only relies on real hardware status
>
> v11:
> - Replaced lockable_reg with simplified function (Michal)
> - Used new macros for locking bits of WOPCM size/offset registers instead
> of using BIT(0) directly (Michal)
> - use intel_wopcm_init_hw() called from intel_gem_init_hw() to do GuC
> WOPCM register setup instead of calling from intel_uc_init_hw() (Michal)
>
> v12:
> - Updated function kernel-doc to align with code changes (Michal)
> - Updated code to use wopcm pointer directly (Michal)
>
> v13:
> - Updated the ordering of s-o-b/cc/r-b tags (Sagar)
>
> BSpec: 10875, 10833
>
> Signed-off-by: Jackie Li <yaodong.li@xxxxxxxxx>
> Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Reviewed-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx> (v11)
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> (v12)
<SNIP>
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -5147,6 +5147,12 @@ int i915_gem_init_hw(struct drm_i915_private *dev_priv)
> goto out;
> }
>
> + ret = intel_wopcm_init_hw(&dev_priv->wopcm);
> + if (ret) {
> + DRM_ERROR("Enabling WOPCM failed (%d)\n", ret);
This (or the other instance inside) can still be removed, it's a duplicate
message.
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
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