[Intel-gfx] [PATCH] drm/i915: Use wait_for_register in lpt_reset_fdi_mphy()

[Chris Wilson]

On Mon, Apr 10, 2017 at 08:53:25AM +0000, Michal Wajdeczko wrote:
> There is no need to use macros as we can use generic function.
> And we can save ~2000 bytes in driver footprint.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index b6b40cd..63f9dae4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7697,22 +7697,30 @@ static void ironlake_init_pch_refclk(struct drm_i915_private *dev_priv)
>  
>  static void lpt_reset_fdi_mphy(struct drm_i915_private *dev_priv)
>  {
> +	int ret;
>  	uint32_t tmp;
>  
>  	tmp = I915_READ(SOUTH_CHICKEN2);
>  	tmp |= FDI_MPHY_IOSFSB_RESET_CTL;
>  	I915_WRITE(SOUTH_CHICKEN2, tmp);
>  
> -	if (wait_for_us(I915_READ(SOUTH_CHICKEN2) &
> -			FDI_MPHY_IOSFSB_RESET_STATUS, 100))
> +	ret = __intel_wait_for_register_fw(dev_priv,
> +					   SOUTH_CHICKEN2,
> +					   FDI_MPHY_IOSFSB_RESET_STATUS,
> +					   FDI_MPHY_IOSFSB_RESET_STATUS,
> +					   100, 0, &tmp);
> +	if (ret)
>  		DRM_ERROR("FDI mPHY reset assert timeout\n");

If we aren't using ret, and if the function remains neatly aligned I
would have just done

	if ( __intel_wait_for_register_fw(dev_priv, ...))
  		DRM_ERROR("FDI mPHY reset assert timeout\n");

I would also let it have a 10ms max timeout - there's no downside. We
didn't before because of the expense of the wait_for() loops, and this
must be a waitable context.

Hmm. We do want __inte_wait_for_register_fw:
	might_sleep_if(fast_timeout_us > 10 || slow_timeout_ms);
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre