Re: [PATCH 2/5] drm/i915/snps_phy: Use HDMI PLL algorithm for DG2

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

On Wed, 26 Jun 2024, Ankit Nautiyal <ankit.k.nautiyal@intel.com> wrote:
> Try SNPS_PHY HDMI tables computed using the algorithm, before using
> consolidated tables.
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_snps_phy.c | 20 ++++++++-----------
>  1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_snps_phy.c b/drivers/gpu/drm/i915/display/intel_snps_phy.c
> index e6df1f92def5..10fe28af0d11 100644
> --- a/drivers/gpu/drm/i915/display/intel_snps_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_snps_phy.c
> @@ -12,6 +12,7 @@
>  #include "intel_display_types.h"
>  #include "intel_snps_phy.h"
>  #include "intel_snps_phy_regs.h"
> +#include "intel_pll_algorithm.h"

Keep includes sorted.

>  
>  /**
>   * DOC: Synopsis PHY support
> @@ -1787,22 +1788,14 @@ intel_mpllb_tables_get(struct intel_crtc_state *crtc_state,
>  int intel_mpllb_calc_state(struct intel_crtc_state *crtc_state,
>  			   struct intel_encoder *encoder)
>  {
> -	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
>  	const struct intel_mpllb_state * const *tables;
>  	int i;
>  
>  	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
> -		if (intel_snps_phy_check_hdmi_link_rate(crtc_state->port_clock)
> -		    != MODE_OK) {
> -			/*
> -			 * FIXME: Can only support fixed HDMI frequencies
> -			 * until we have a proper algorithm under a valid
> -			 * license.
> -			 */
> -			drm_dbg_kms(&i915->drm, "Can't support HDMI link rate %d\n",
> -				    crtc_state->port_clock);
> -			return -EINVAL;
> -		}
> +		/* try computed SNPS_PHY HDMI tables before using consolidated tables */

Computed tables vs. consolidated tables? Huh?

Anyway, I think we have two choices here:

- Always use computed values.

- Prefer fixed tables, fall back to computed values.

But we definitely should not try to compute first and fall back to fixed
tables.

> +		if (intel_snps_phy_compute_hdmi_tmds_pll(crtc_state->port_clock,
> +							 &crtc_state->dpll_hw_state.mpllb) == 0)
> +			return 0;
>  	}
>  
>  	tables = intel_mpllb_tables_get(crtc_state, encoder);
> @@ -1991,6 +1984,9 @@ int intel_snps_phy_check_hdmi_link_rate(int clock)
>  			return MODE_OK;
>  	}
>  
> +	if (clock >= 25175 && clock <= 594000)
> +		return MODE_OK;
> +

How's this related to the patch at hand?

>  	return MODE_CLOCK_RANGE;
>  }

-- 
Jani Nikula, Intel