Re: [PATCH 5/6] drm/i915/display: add "is" member to struct intel_display

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Jun 18, 2024 at 05:22:55PM +0300, Jani Nikula wrote:
> Facilitate using display->is.HASWELL etc. for identifying platforms and
> subplatforms. Merge platform and subplatform members together.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  .../gpu/drm/i915/display/intel_display_core.h |  3 +++
>  .../drm/i915/display/intel_display_device.c   | 19 +++++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
> index 7715fc329057..35bea92893af 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> @@ -286,6 +286,9 @@ struct intel_display {
>  	/* drm device backpointer */
>  	struct drm_device *drm;
>  
> +	/* Platform identification */
> +	struct intel_display_is is;
> +
>  	/* Display functions */
>  	struct {
>  		/* Top level crtc-ish functions */
> diff --git a/drivers/gpu/drm/i915/display/intel_display_device.c b/drivers/gpu/drm/i915/display/intel_display_device.c
> index 0c275d85bd30..954caea38005 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_device.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_device.c
> @@ -1269,8 +1269,25 @@ find_subplatform_desc(struct pci_dev *pdev, const struct platform_desc *desc)
>  	return NULL;
>  }
>  
> +static void mem_or(void *_dst, const void *_src, size_t size)
> +{
> +	const u8 *src = _src;
> +	u8 *dst = _dst;
> +	size_t i;
> +
> +	for (i = 0; i < size; i++)
> +		dst[i] |= src[i];

I confess that here I got a bit lost. But I believe it is just a matter of
adding a few comments in the code or perhaps adjusting function names...

If my coffee is working well still, what we are doing here is ensuring that:

is.HASWELL returns true regardless the subplatform this is coming from...
like is.HASWELL_ULT or is.HASWELL_ULX.

But since you are only doing dst |= src and not doing src |= dst and also
not calling this function for different subplatforms, then individually
is.HASWELL_ULT is false for ULX platform and vice-versa.

Perhaps the name 'merge' is not a good one?

> +}
> +
> +static void merge_display_is(struct intel_display_is *dst,
> +			     const struct intel_display_is *src)
> +{
> +	mem_or(dst, src, sizeof(*dst));

and/or perhaps we don't need this extra indirection here?

> +}
> +
>  void intel_display_device_probe(struct drm_i915_private *i915)
>  {
> +	struct intel_display *display = &i915->display;
>  	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
>  	const struct intel_display_device_info *info;
>  	struct intel_display_ip_ver ip_ver = {};
> @@ -1308,11 +1325,13 @@ void intel_display_device_probe(struct drm_i915_private *i915)
>  
>  	drm_WARN_ON(&i915->drm, !desc->platform || !desc->name);
>  	DISPLAY_RUNTIME_INFO(i915)->platform = desc->platform;
> +	display->is = desc->is;
>  
>  	subdesc = find_subplatform_desc(pdev, desc);
>  	if (subdesc) {
>  		drm_WARN_ON(&i915->drm, !subdesc->subplatform || !subdesc->name);
>  		DISPLAY_RUNTIME_INFO(i915)->subplatform = subdesc->subplatform;
> +		merge_display_is(&display->is, &subdesc->is);
>  	}
>  
>  	if (ip_ver.ver || ip_ver.rel || ip_ver.step)
> -- 
> 2.39.2
>