Re: [PATCH 2/8] drm/i915/de: Pimp the intel_de_{read, write}_fw() docs

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 13 Nov 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Include a bit more guidance on when to use or not use
> intel_de_{read,write}_fw(), and what the extra caveats
> are.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_de.h | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_de.h b/drivers/gpu/drm/i915/display/intel_de.h
> index a6dcb91b36f2..2c469a2d6a20 100644
> --- a/drivers/gpu/drm/i915/display/intel_de.h
> +++ b/drivers/gpu/drm/i915/display/intel_de.h
> @@ -87,12 +87,19 @@ int intel_de_wait_for_clear_ms(struct intel_display *display, intel_reg_t reg,
>  			       u32 mask, unsigned int timeout_ms);
>  
>  /*
> - * Unlocked mmio-accessors, think carefully before using these.
> + * Unlocked mmio-accessors, think carefully before using these. Generally only
> + * highly performance sensitive code should use these (eg. vblank evade critical
> + * section, or interrupt handlers).
>   *
>   * Certain architectures will die if the same cacheline is concurrently accessed
> - * by different clients (e.g. on Ivybridge). Access to registers should
> - * therefore generally be serialised, by either the dev_priv->uncore.lock or
> + * by different clients (e.g. on Ivybridge/Haswell). Access to registers should
> + * therefore generally be serialised, by either the display->mmio.lock or
>   * a more localised lock guarding all access to that bank of registers.
> + *
> + * DMC wakelock will not be taken by these. It must be done manually,
> + * if needed.

Is there anything we could mention here about what "if needed" really
means?

Regardless,

Reviewed-by: Jani Nikula <jani.nikula@intel.com>


> + *
> + * These will also skip the mmio_debug unclaimed register detection.
>   */
>  u32 intel_de_read_fw(struct intel_display *display, intel_reg_t reg);
>  void intel_de_write_fw(struct intel_display *display, intel_reg_t reg, u32 val);

-- 
Jani Nikula, Intel