Re: [PATCH 5/5] drm/i915/bxt: add DDI port HW readout support

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jun 18, 2015 at 05:25:57PM +0300, Imre Deak wrote:
> Add support for reading out the HW state for DDI ports. Since the actual
> programming is very similar to the CHV/VLV DPIO PLL programming we can
> reuse much of the logic from there.
> 
> This fixes the state checker failures I saw on my BXT with HDMI output.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h  | 15 +++++++++------
>  drivers/gpu/drm/i915/intel_ddi.c | 22 ++++++++++++++++++++--
>  2 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index bba0691..fcf6ad5 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1169,10 +1169,12 @@ enum skl_disp_power_wells {
>  #define _PORT_PLL_EBB_0_A		0x162034
>  #define _PORT_PLL_EBB_0_B		0x6C034
>  #define _PORT_PLL_EBB_0_C		0x6C340
> -#define   PORT_PLL_P1_MASK		(0x07 << 13)
> -#define   PORT_PLL_P1(x)		((x)  << 13)
> -#define   PORT_PLL_P2_MASK		(0x1f << 8)
> -#define   PORT_PLL_P2(x)		((x)  << 8)
> +#define   PORT_PLL_P1_SHIFT		13
> +#define   PORT_PLL_P1_MASK		(0x07 << PORT_PLL_P1_SHIFT)
> +#define   PORT_PLL_P1(x)		((x)  << PORT_PLL_P1_SHIFT)
> +#define   PORT_PLL_P2_SHIFT		8
> +#define   PORT_PLL_P2_MASK		(0x1f << PORT_PLL_P2_SHIFT)
> +#define   PORT_PLL_P2(x)		((x)  << PORT_PLL_P2_SHIFT)
>  #define BXT_PORT_PLL_EBB_0(port)	_PORT3(port, _PORT_PLL_EBB_0_A, \
>  						_PORT_PLL_EBB_0_B,	\
>  						_PORT_PLL_EBB_0_C)
> @@ -1192,8 +1194,9 @@ enum skl_disp_power_wells {
>  /* PORT_PLL_0_A */
>  #define   PORT_PLL_M2_MASK		0xFF
>  /* PORT_PLL_1_A */
> -#define   PORT_PLL_N_MASK		(0x0F << 8)
> -#define   PORT_PLL_N(x)			((x) << 8)
> +#define   PORT_PLL_N_SHIFT		8
> +#define   PORT_PLL_N_MASK		(0x0F << PORT_PLL_N_SHIFT)
> +#define   PORT_PLL_N(x)			((x) << PORT_PLL_N_SHIFT)
>  /* PORT_PLL_2_A */
>  #define   PORT_PLL_M2_FRAC_MASK		0x3FFFFF
>  /* PORT_PLL_3_A */
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index ca970ba..6859068 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -971,8 +971,26 @@ static void hsw_ddi_clock_get(struct intel_encoder *encoder,
>  static int bxt_calc_pll_link(struct drm_i915_private *dev_priv,
>  				enum intel_dpll_id dpll)
>  {
> -	/* FIXME formula not available in bspec */
> -	return 0;
> +	struct intel_shared_dpll *pll;
> +	struct intel_dpll_hw_state *state;
> +	intel_clock_t clock;
> +
> +	/* For DDI ports we always use a shared PLL. */
> +	if (WARN_ON(dpll == DPLL_ID_PRIVATE))
> +		return 0;
> +
> +	pll = &dev_priv->shared_dplls[dpll];
> +	state = &pll->config.hw_state;
> +
> +	clock.m1 = 2;

For chv I opted to read out the m1 divider from PLL_DW1 too even though
2 is the only supported value. Doing so might catch some cases where the
register gets misprogrammed.

But that's a minor issue, so even without this is
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +	clock.m2 = (state->pll0 & PORT_PLL_M2_MASK) << 22;
> +	if (state->pll3 & PORT_PLL_M2_FRAC_ENABLE)
> +		clock.m2 |= state->pll2 & PORT_PLL_M2_FRAC_MASK;

I just realized we're missing the fracnen check from chv_crtc_clock_get().
Care to send a patch to add the check there as well?

> +	clock.n = (state->pll1 & PORT_PLL_N_MASK) >> PORT_PLL_N_SHIFT;
> +	clock.p1 = (state->ebb0 & PORT_PLL_P1_MASK) >> PORT_PLL_P1_SHIFT;
> +	clock.p2 = (state->ebb0 & PORT_PLL_P2_MASK) >> PORT_PLL_P2_SHIFT;
> +
> +	return vlv_calc_port_clock(100000, &clock);
>  }
>  
>  static void bxt_ddi_clock_get(struct intel_encoder *encoder,
> -- 
> 2.1.4
> 
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-- 
Ville Syrjälä
Intel OTC
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