Re: [PATCH v6 3/4] drm/i915/psr: Make PSR registers relative to transcoders

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 19 Jun 2019, José Roberto de Souza <jose.souza@intel.com> wrote:
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 4fc8dc083766..31fb4de5081c 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4225,10 +4225,18 @@ enum {
>  #define PIPESRC(trans)		_MMIO_TRANS2(trans, _PIPEASRC)
>  #define PIPE_MULT(trans)	_MMIO_TRANS2(trans, _PIPE_MULT_A)
>  
> -/* HSW+ eDP PSR registers */
> -#define HSW_EDP_PSR_BASE	0x64800
> -#define BDW_EDP_PSR_BASE	0x6f800
> -#define EDP_PSR_CTL				_MMIO(dev_priv->psr_mmio_base + 0)
> +/*
> + * HSW+ eDP PSR registers
> + *
> + * HSW PSR registers are relative to DDIA(_DDI_BUF_CTL_A + 0x800) with just one
> + * instance of it
> + */
> +#define _HSW_EDP_PSR_BASE			0x64800
> +#define _SRD_CTL_A				0x60800
> +#define _SRD_CTL_EDP				0x6f800
> +#define _HSW_PSR_ADJ(reg)			((reg) - _SRD_CTL_A + _HSW_EDP_PSR_BASE)
> +#define _PSR_ADJ(tran, reg)			(IS_HASWELL(dev_priv) ? _HSW_PSR_ADJ(reg) : _TRANS2(tran, reg))
> +#define EDP_PSR_CTL(tran)			_MMIO(_PSR_ADJ(tran, _SRD_CTL_A))

There are currently three instances of platform/gen checks in
i915_reg.h. They are the exception, and they're in individual macros
that aren't even register offset definitions let alone helpers that get
proliferated to several other macros.

This change here is quite a big precedent in that regard, and not to be
done lightly. Usually the case is others will follow suit, so this is
not just about this one instance. It's about deciding whether this is
the direction we want to take. How far are we prepared to go and how do
we stop there?

There's really no way to set the psr->transcoder such on HSW that it
would work with MMIO_TRANS2()?

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center
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