[Intel-gfx] [PATCH v5 05/11] drm/i915/dsb: Check DSB engine status.

[Sharma, Shashank]

> -----Original Message-----
> From: Manna, Animesh
> Sent: Monday, September 9, 2019 10:27 PM
> To: Sharma, Shashank <shashank.sharma at intel.com>; intel-
> gfx at lists.freedesktop.org
> Cc: Thierry, Michel <michel.thierry at intel.com>; Nikula, Jani <jani.nikula at intel.com>;
> Vivi, Rodrigo <rodrigo.vivi at intel.com>
> Subject: Re: [PATCH v5 05/11] drm/i915/dsb: Check DSB engine status.
> 
> 
> 
> On 9/9/2019 6:43 PM, Sharma, Shashank wrote:
> >
> > On 9/7/2019 4:37 PM, Animesh Manna wrote:
> >> As per bspec check for DSB status before programming any of its
> >> register. Inline function added to check the dsb status.
> >>
> >> Cc: Michel Thierry <michel.thierry at intel.com>
> >> Cc: Jani Nikula <jani.nikula at intel.com>
> >> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> >> Cc: Shashank Sharma <shashank.sharma at intel.com>
> >> Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> >> ---
> >>   drivers/gpu/drm/i915/display/intel_dsb.c | 9 +++++++++
> >>   drivers/gpu/drm/i915/i915_reg.h          | 7 +++++++
> >>   2 files changed, 16 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
> >> b/drivers/gpu/drm/i915/display/intel_dsb.c
> >> index 0f55ed683d41..2c8415518c65 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> >> @@ -17,6 +17,15 @@
> >>   #define DSB_BYTE_EN_SHIFT        20
> >>   #define DSB_REG_VALUE_MASK        0xfffff
> >>   +static inline bool is_dsb_busy(struct intel_dsb *dsb)
> >> +{
> >> +    struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
> >> +    struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> >> +    enum pipe pipe = crtc->pipe;
> >> +
> >> +    return DSB_STATUS & I915_READ(DSB_CTRL(pipe, dsb->id)); }
> >> +
> >>   struct intel_dsb *
> >>   intel_dsb_get(struct intel_crtc *crtc)
> >>   {
> >> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> >> b/drivers/gpu/drm/i915/i915_reg.h index 006cffd56be2..a3099f712ae6
> >> 100644
> >> --- a/drivers/gpu/drm/i915/i915_reg.h
> >> +++ b/drivers/gpu/drm/i915/i915_reg.h
> >> @@ -11676,4 +11676,11 @@ enum skl_power_gate {
> >>   #define PORT_TX_DFLEXDPCSSS(fia)        _MMIO_FIA((fia), 0x00894)
> >>   #define   DP_PHY_MODE_STATUS_NOT_SAFE(tc_port)        (1 << (tc_port))
> >>   +/* This register controls the Display State Buffer (DSB) engines.
> >> */
> >> +#define _DSBSL_INSTANCE_BASE        0x70B00
> >> +#define DSBSL_INSTANCE(pipe, id)    (_DSBSL_INSTANCE_BASE + \
> >> +                     (pipe) * 0x1000 + (id) * 100)
> >
> > Why is pipe in () ?
> 
> mmio offset per DSB depend on pipe and dsb-id (3 DSB per pipe.) offset of PIPE_A
> DSB1-> 70B00 offset of PIPE_B DSB1-> 71B00 and so on...
> 
The question here is why is the 'pipe' in braces ? why is it '(pipe)', instead of 'pipe'. I don’t see a reason. 
- Shashank
> Regards,
> Animesh