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

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

On Fri, Jan 13, 2017 at 05:03:33PM +0200, Imre Deak wrote:
> 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?

Full modesets should be serialized by connection_mutex, or perhaps by
some other thing with async modesets. Although I have a feeling that if
we're doing async modeset commits without locks half the driveer is
going to be on fire. Not sure what people are doing/have planned there.

> 
> 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 */
> > 

-- 
Ville Syrjälä
Intel OTC
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