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

Imre Deak
2015-06-22T14:22:35Z

On ma, 2015-06-22 at 16:44 +0300, Ville Syrjälä wrote:
> 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.

I haven't found the BXT counterpart for this at least when looking
through BSpec. PORT_PLL_1[2:0] is "i_fbpredivratio" and it reads 0 for
me.

> 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?

Ok.

> > + clock.n = (state->pll1 & PORT_PLL_N_MASK) >> PORT_PLL_N_SHIFT;

Btw, now that I looked through BSpec and the code again, this looks like
also be tied to 1, so we'd need to check for this in
bxt_ddi_pll_select(). chv_find_best_dpll() does the right thing already.

> > + 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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