Re: [PATCH v3 08/13] drm/bridge: analogix-anx78xx: Avoid drm_dp_link helpers

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Oct 21, 2019 at 04:34:32PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> During the discussion of patches that enhance the drm_dp_link helpers it
> was concluded that these helpers aren't very useful to begin with. Start
> pushing the equivalent code into individual drivers to ultimately remove
> them.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/gpu/drm/bridge/analogix-anx78xx.c | 57 +++++++++++++++++------
>  1 file changed, 42 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix-anx78xx.c
> index 9ddc1f3cf841..8bb4793f382b 100644
> --- a/drivers/gpu/drm/bridge/analogix-anx78xx.c
> +++ b/drivers/gpu/drm/bridge/analogix-anx78xx.c
> @@ -71,7 +71,6 @@ struct anx78xx {
>  	struct i2c_client *client;
>  	struct edid *edid;
>  	struct drm_connector connector;
> -	struct drm_dp_link link;
>  	struct anx78xx_platform_data pdata;
>  	struct mutex lock;
>  
> @@ -801,18 +800,34 @@ static int anx78xx_dp_link_training(struct anx78xx *anx78xx)
>  	if (err)
>  		return err;
>  
> -	/* Check link capabilities */
> -	err = drm_dp_link_probe(&anx78xx->aux, &anx78xx->link);
> -	if (err < 0) {
> -		DRM_ERROR("Failed to probe link capabilities: %d\n", err);
> -		return err;
> -	}
> +	/*
> +	 * Power up the sink (DP_SET_POWER register is only available on DPCD
> +	 * v1.1 and later).
> +	 */
> +	if (anx78xx->dpcd[DP_DPCD_REV] >= 0x11) {
> +		err = drm_dp_dpcd_readb(&anx78xx->aux, DP_SET_POWER, &value);
> +		if (err < 0) {
> +			DRM_ERROR("Failed to read DP_SET_POWER register: %d\n",
> +				  err);
> +			return err;
> +		}
>  
> -	/* Power up the sink */
> -	err = drm_dp_link_power_up(&anx78xx->aux, &anx78xx->link);
> -	if (err < 0) {
> -		DRM_ERROR("Failed to power up DisplayPort link: %d\n", err);
> -		return err;
> +		value &= ~DP_SET_POWER_MASK;
> +		value |= DP_SET_POWER_D0;
> +
> +		err = drm_dp_dpcd_writeb(&anx78xx->aux, DP_SET_POWER, value);
> +		if (err < 0) {
> +			DRM_ERROR("Failed to power up DisplayPort link: %d\n",
> +				  err);
> +			return err;
> +		}
> +
> +		/*
> +		 * According to the DP 1.1 specification, a "Sink Device must
> +		 * exit the power saving state within 1 ms" (Section 2.5.3.1,
> +		 * Table 5-52, "Sink Control Field" (register 0x600).
> +		 */
> +		usleep_range(1000, 2000);
>  	}
>  
>  	/* Possibly enable downspread on the sink */
> @@ -851,15 +866,27 @@ static int anx78xx_dp_link_training(struct anx78xx *anx78xx)
>  	if (err)
>  		return err;
>  
> -	value = drm_dp_link_rate_to_bw_code(anx78xx->link.rate);
> +	value = drm_dp_max_link_rate(anx78xx->dpcd);
> +	value = drm_dp_link_rate_to_bw_code(value);
>  	err = regmap_write(anx78xx->map[I2C_IDX_TX_P0],
>  			   SP_DP_MAIN_LINK_BW_SET_REG, value);
>  	if (err)
>  		return err;
>  
> -	err = drm_dp_link_configure(&anx78xx->aux, &anx78xx->link);
> +	err = drm_dp_dpcd_writeb(&anx78xx->aux, DP_LINK_BW_SET, value);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to set link bandwidth: %d\n", err);
> +		return err;
> +	}
> +
> +	value = drm_dp_max_lane_count(anx78xx->dpcd);
> +
> +	if (drm_dp_enhanced_frame_cap(anx78xx->dpcd))
> +		value |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
> +
> +	err = drm_dp_dpcd_writeb(&anx78xx->aux, DP_LANE_COUNT_SET, value);
>  	if (err < 0) {
> -		DRM_ERROR("Failed to configure DisplayPort link: %d\n", err);
> +		DRM_ERROR("Failed to set link lane count: %d\n", err);
>  		return err;

Splits the last two writes into 2 transactions, otherwise looks
equivalent.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

>  	}
>  
> -- 
> 2.23.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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