On Tue, 2017-08-08 at 08:51 -0700, Jim Bride wrote:
> Bit 29 of SRD_CTL needs to have its value preserved,
probably good to kind of quote spec somehow:
"This field is used for hardware communication. Software must not
change this field."
> so right before we
> write out the register we go ahead and read the register and preserve
> the value of that bit before we write out the configured register value.
>
> Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nik...@intel.com>
> Signed-off-by: Jim Bride <jim.br...@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_psr.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index b2546ad..ea8e421 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3872,6 +3872,7 @@ enum {
> #define EDP_PSR_CTL _MMIO(dev_priv->psr_mmio_base +
> 0)
> #define EDP_PSR_ENABLE (1<<31)
> #define BDW_PSR_SINGLE_FRAME (1<<30)
> +#define EDP_PSR_RESTORE_PSR_ACTIVE_CTX (1<<29) /* SW can't modify */
- please use real tabs instead of spaces.
- a MASK on the name is better since we are not using this define to set
the bit, but to mask instead.
> #define EDP_PSR_LINK_STANDBY (1<<27)
> #define EDP_PSR_MIN_LINK_ENTRY_TIME_MASK (3<<25)
> #define EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES (0<<25)
> diff --git a/drivers/gpu/drm/i915/intel_psr.c
> b/drivers/gpu/drm/i915/intel_psr.c
> index 559f1ab..0d08efa 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -315,6 +315,7 @@ static void intel_enable_source_psr1(struct intel_dp
> *intel_dp)
> else
> val |= EDP_PSR_TP1_TP2_SEL;
>
I wondered if we should add an extra comment here, but I believe it is
not necessary if we have the "_MASK" on the bit name.
> + val |= I915_READ(EDP_PSR_CTL) & EDP_PSR_RESTORE_PSR_ACTIVE_CTX;
> I915_WRITE(EDP_PSR_CTL, val);
> }
>
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