Re: [PATCH 10/14] drm/i915: Add MIPI_IO WA

[Imre Deak <imre.deak@intel.com>]

On pe, 2017-01-13 at 09:55 +0200, Jani Nikula wrote:
> On Thu, 12 Jan 2017, Mika Kahola <mika.kahola@intel.com> wrote:
> > This is definitely needed to pass igt test on bxt
> > 
> > 'gem_exec_suspend --run-subtest basic-S3'
> > 
> > Tested-by: Mika Kahola <mika.kahola@intel.com>
> > 
> > On Mon, 2017-01-09 at 14:46 +0530, Vidya Srinivas wrote:
> > > From: Uma Shankar <uma.shankar@intel.com>
> > > 
> > > Enable MIPI IO WA for BXT DSI as per bspec.
> > > 
> > > Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_reg.h  | 3 +++
> > >  drivers/gpu/drm/i915/intel_dsi.c | 9 +++++++++
> > >  2 files changed, 12 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > > b/drivers/gpu/drm/i915/i915_reg.h
> > > index 71b978a..b9d7e98 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -8301,6 +8301,9 @@ enum {
> > >  #define _BXT_MIPIC_PORT_CTRL				0x6B8C0
> > >  #define BXT_MIPI_PORT_CTRL(tc)	_MMIO_MIPI(tc,
> > > _BXT_MIPIA_PORT_CTRL, _BXT_MIPIC_PORT_CTRL)
> > >  
> > > +#define BXT_P_CR_GT_DISP_PWRON_0_2_0_GTTMMADR		_MMIO(0
> > > x138090)
> 
> Observe that this register is already defined as BXT_P_CR_GT_DISP_PWRON,
> and already used in intel_dpio_phy.c. It seems to me changing the bits
> in this register should be hooked at the dpio level.
> 
> Imre?

At least the RMW access for this register would need locking against a
concurrent access via the DDI encoder enable/disable code?

We should also make sure the IO is turned off during booting/resuming
if DSI won't be used (and so the DSI disable hook won't be called), see
the BSpec "Broxton Sequences to Initialize Display". We could do this
by enabling/disabling the IO via the power well code which would solve
the locking issue too. This would mean using POWER_DOMAIN_PORT_DSI, or
adding a new power domain if diverging from the BSpec sequence is a
problem (would be worth checking with HW people, since AFAICS we've
been doing this so far).

Btw, what about the 0x160020, 0x160054 regs? According to BSpec we need
to program these too in the same sequence.

--Imre

> > > +#define  MIPIO_RST_CTRL					(1 <<
> > > 2)
> > > +
> > >  #define  DPI_ENABLE					(1 << 31)
> > > /* A + C */
> > >  #define  MIPIA_MIPI4DPHY_DELAY_COUNT_SHIFT		27
> > >  #define  MIPIA_MIPI4DPHY_DELAY_COUNT_MASK		(0xf << 27)
> > > diff --git a/drivers/gpu/drm/i915/intel_dsi.c
> > > b/drivers/gpu/drm/i915/intel_dsi.c
> > > index a4bda92..9252490 100644
> > > --- a/drivers/gpu/drm/i915/intel_dsi.c
> > > +++ b/drivers/gpu/drm/i915/intel_dsi.c
> > > @@ -366,6 +366,11 @@ static void bxt_dsi_device_ready(struct
> > > intel_encoder *encoder)
> > >  
> > >  	DRM_DEBUG_KMS("\n");
> > >  
> > > +	/* Add MIPI IO reset programming for modeset */
> > > +	val = I915_READ(BXT_P_CR_GT_DISP_PWRON_0_2_0_GTTMMADR);
> > > +	I915_WRITE(BXT_P_CR_GT_DISP_PWRON_0_2_0_GTTMMADR,
> > > +					val | MIPIO_RST_CTRL);
> > > +
> > Should we move this WA to intel_dsi_pre_enable() as the counterpart of
> > this WA is defined intel_dsi_post_disable()?
> 
> As I said, this should probably be managed in intel_dpio_phy.c.
> 
> And if not, this is BXT specific, and this hunk runs it on everything
> else too.
> 
> BR,
> Jani.
> 
> 
> > 
> > >  	/* Enable MIPI PHY transparent latch */
> > >  	for_each_dsi_port(port, intel_dsi->ports) {
> > >  		val = I915_READ(BXT_MIPI_PORT_CTRL(port));
> > > @@ -757,6 +762,10 @@ static void intel_dsi_post_disable(struct
> > > intel_encoder *encoder,
> > >  	drm_panel_power_off(intel_dsi->panel);
> > >  	msleep(intel_dsi->panel_off_delay);
> > >  
> > > +	val = I915_READ(BXT_P_CR_GT_DISP_PWRON_0_2_0_GTTMMADR);
> > > +	I915_WRITE(BXT_P_CR_GT_DISP_PWRON_0_2_0_GTTMMADR,
> > > +					val & ~MIPIO_RST_CTRL);
> > > +
> > >  	intel_disable_dsi_pll(encoder);
> > >  
> > >  	/* Panel Disable over CRC PMIC */
> 
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