Re: [PATCH 08/10] drm/i915: Merge sbi read/write into a single accessor

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

On Fri, Apr 19, 2019 at 06:14:00PM +0100, Chris Wilson wrote:
> Since intel_sideband_read and intel_sideband_write differ by only a
> couple of lines (depending on whether we feed the value in or out),
> merge the two into a single common accessor.
> 
> v2: Restore vlv_flisdsi_read() lost during rebasing.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Looks equivalent

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_sideband.c | 94 +++++++++++----------------
>  1 file changed, 38 insertions(+), 56 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c
> index 5c3ae5185a01..7113fb8850d6 100644
> --- a/drivers/gpu/drm/i915/intel_sideband.c
> +++ b/drivers/gpu/drm/i915/intel_sideband.c
> @@ -273,81 +273,63 @@ void vlv_flisdsi_write(struct drm_i915_private *i915, u32 reg, u32 val)
>  }
>  
>  /* SBI access */
> -u32 intel_sbi_read(struct drm_i915_private *dev_priv, u16 reg,
> -		   enum intel_sbi_destination destination)
> +static int intel_sbi_rw(struct drm_i915_private *i915, u16 reg,
> +			enum intel_sbi_destination destination,
> +			u32 *val, bool is_read)
>  {
> -	u32 value = 0;
> +	struct intel_uncore *uncore = &i915->uncore;
> +	u32 cmd;
>  
> -	lockdep_assert_held(&dev_priv->sb_lock);
> +	lockdep_assert_held(&i915->sb_lock);
>  
> -	if (intel_wait_for_register(&dev_priv->uncore,
> -				    SBI_CTL_STAT, SBI_BUSY, 0,
> -				    100)) {
> +	if (intel_wait_for_register_fw(uncore,
> +				       SBI_CTL_STAT, SBI_BUSY, 0,
> +				       100)) {
>  		DRM_ERROR("timeout waiting for SBI to become ready\n");
> -		return 0;
> +		return -EBUSY;
>  	}
>  
> -	I915_WRITE(SBI_ADDR, (reg << 16));
> -	I915_WRITE(SBI_DATA, 0);
> +	intel_uncore_write_fw(uncore, SBI_ADDR, (u32)reg << 16);
> +	intel_uncore_write_fw(uncore, SBI_DATA, is_read ? 0 : *val);
>  
>  	if (destination == SBI_ICLK)
> -		value = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
> +		cmd = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
>  	else
> -		value = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IORD;
> -	I915_WRITE(SBI_CTL_STAT, value | SBI_BUSY);
> -
> -	if (intel_wait_for_register(&dev_priv->uncore,
> -				    SBI_CTL_STAT,
> -				    SBI_BUSY,
> -				    0,
> -				    100)) {
> +		cmd = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IORD;
> +	if (!is_read)
> +		cmd |= BIT(8);
> +	intel_uncore_write_fw(uncore, SBI_CTL_STAT, cmd | SBI_BUSY);
> +
> +	if (__intel_wait_for_register_fw(uncore,
> +					 SBI_CTL_STAT, SBI_BUSY, 0,
> +					 100, 100, &cmd)) {
>  		DRM_ERROR("timeout waiting for SBI to complete read\n");
> -		return 0;
> +		return -ETIMEDOUT;
>  	}
>  
> -	if (I915_READ(SBI_CTL_STAT) & SBI_RESPONSE_FAIL) {
> +	if (cmd & SBI_RESPONSE_FAIL) {
>  		DRM_ERROR("error during SBI read of reg %x\n", reg);
> -		return 0;
> +		return -ENXIO;
>  	}
>  
> -	return I915_READ(SBI_DATA);
> +	if (is_read)
> +		*val = intel_uncore_read_fw(uncore, SBI_DATA);
> +
> +	return 0;
>  }
>  
> -void intel_sbi_write(struct drm_i915_private *dev_priv, u16 reg, u32 value,
> -		     enum intel_sbi_destination destination)
> +u32 intel_sbi_read(struct drm_i915_private *i915, u16 reg,
> +		   enum intel_sbi_destination destination)
>  {
> -	u32 tmp;
> +	u32 result = 0;
>  
> -	lockdep_assert_held(&dev_priv->sb_lock);
> +	intel_sbi_rw(i915, reg, destination, &result, true);
>  
> -	if (intel_wait_for_register(&dev_priv->uncore,
> -				    SBI_CTL_STAT, SBI_BUSY, 0,
> -				    100)) {
> -		DRM_ERROR("timeout waiting for SBI to become ready\n");
> -		return;
> -	}
> -
> -	I915_WRITE(SBI_ADDR, (reg << 16));
> -	I915_WRITE(SBI_DATA, value);
> -
> -	if (destination == SBI_ICLK)
> -		tmp = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRWR;
> -	else
> -		tmp = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IOWR;
> -	I915_WRITE(SBI_CTL_STAT, SBI_BUSY | tmp);
> -
> -	if (intel_wait_for_register(&dev_priv->uncore,
> -				    SBI_CTL_STAT,
> -				    SBI_BUSY,
> -				    0,
> -				    100)) {
> -		DRM_ERROR("timeout waiting for SBI to complete write\n");
> -		return;
> -	}
> +	return result;
> +}
>  
> -	if (I915_READ(SBI_CTL_STAT) & SBI_RESPONSE_FAIL) {
> -		DRM_ERROR("error during SBI write of %x to reg %x\n",
> -			  value, reg);
> -		return;
> -	}
> +void intel_sbi_write(struct drm_i915_private *i915, u16 reg, u32 value,
> +		     enum intel_sbi_destination destination)
> +{
> +	intel_sbi_rw(i915, reg, destination, &value, false);
>  }
> -- 
> 2.20.1
> 
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-- 
Ville Syrjälä
Intel
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