Re: [Intel-gfx] [v4 3/7] drm/i915/dsi: wait for header and payload credit available

["Kulkarni, Vandita" <vandita.kulkarni@intel.com>]

> -----Original Message-----
> From: Lee, Shawn C <shawn.c.lee@intel.com>
> Sent: Thursday, August 12, 2021 9:13 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Nikula, Jani <jani.nikula@intel.com>; ville.syrjala@linux.intel.com;
> Kulkarni, Vandita <vandita.kulkarni@intel.com>; Chiou, Cooper
> <cooper.chiou@intel.com>; Tseng, William <william.tseng@intel.com>; Lee,
> Shawn C <shawn.c.lee@intel.com>; Jani Nikula <jani.nikula@linux.intel.com>
> Subject: [v4 3/7] drm/i915/dsi: wait for header and payload credit available
> 
> Driver should wait for free header or payload buffer in FIFO.
> It would be good to wait a while for HW to release credit before give it up to
> write to HW. Without sending initailize command sets completely. It would
> caused MIPI display can't light up properly.
> 
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
> Cc: Cooper Chiou <cooper.chiou@intel.com>
> Cc: William Tseng <william.tseng@intel.com>
> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>

Looks good to me.
Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>

> ---
>  drivers/gpu/drm/i915/display/icl_dsi.c | 40 ++++++++++++--------------
>  1 file changed, 19 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c
> b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 43ec7fcd3f5d..1780830d9909 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -54,20 +54,28 @@ static int payload_credits_available(struct
> drm_i915_private *dev_priv,
>  		>> FREE_PLOAD_CREDIT_SHIFT;
>  }
> 
> -static void wait_for_header_credits(struct drm_i915_private *dev_priv,
> -				    enum transcoder dsi_trans)
> +static bool wait_for_header_credits(struct drm_i915_private *dev_priv,
> +				    enum transcoder dsi_trans, int hdr_credit)
>  {
>  	if (wait_for_us(header_credits_available(dev_priv, dsi_trans) >=
> -			MAX_HEADER_CREDIT, 100))
> +			hdr_credit, 100)) {
>  		drm_err(&dev_priv->drm, "DSI header credits not
> released\n");
> +		return false;
> +	}
> +
> +	return true;
>  }
> 
> -static void wait_for_payload_credits(struct drm_i915_private *dev_priv,
> -				     enum transcoder dsi_trans)
> +static bool wait_for_payload_credits(struct drm_i915_private *dev_priv,
> +				     enum transcoder dsi_trans, int
> payld_credit)
>  {
>  	if (wait_for_us(payload_credits_available(dev_priv, dsi_trans) >=
> -			MAX_PLOAD_CREDIT, 100))
> +			payld_credit, 100)) {
>  		drm_err(&dev_priv->drm, "DSI payload credits not
> released\n");
> +		return false;
> +	}
> +
> +	return true;
>  }
> 
>  static enum transcoder dsi_port_to_transcoder(enum port port) @@ -90,8
> +98,8 @@ static void wait_for_cmds_dispatched_to_panel(struct
> intel_encoder *encoder)
>  	/* wait for header/payload credits to be released */
>  	for_each_dsi_port(port, intel_dsi->ports) {
>  		dsi_trans = dsi_port_to_transcoder(port);
> -		wait_for_header_credits(dev_priv, dsi_trans);
> -		wait_for_payload_credits(dev_priv, dsi_trans);
> +		wait_for_header_credits(dev_priv, dsi_trans,
> MAX_HEADER_CREDIT);
> +		wait_for_payload_credits(dev_priv, dsi_trans,
> MAX_PLOAD_CREDIT);
>  	}
> 
>  	/* send nop DCS command */
> @@ -108,7 +116,7 @@ static void
> wait_for_cmds_dispatched_to_panel(struct intel_encoder *encoder)
>  	/* wait for header credits to be released */
>  	for_each_dsi_port(port, intel_dsi->ports) {
>  		dsi_trans = dsi_port_to_transcoder(port);
> -		wait_for_header_credits(dev_priv, dsi_trans);
> +		wait_for_header_credits(dev_priv, dsi_trans,
> MAX_HEADER_CREDIT);
>  	}
> 
>  	/* wait for LP TX in progress bit to be cleared */ @@ -126,18 +134,13
> @@ static bool add_payld_to_queue(struct intel_dsi_host *host, const u8
> *data,
>  	struct intel_dsi *intel_dsi = host->intel_dsi;
>  	struct drm_i915_private *dev_priv = to_i915(intel_dsi-
> >base.base.dev);
>  	enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
> -	int free_credits;
>  	int i, j;
> 
>  	for (i = 0; i < len; i += 4) {
>  		u32 tmp = 0;
> 
> -		free_credits = payload_credits_available(dev_priv,
> dsi_trans);
> -		if (free_credits < 1) {
> -			drm_err(&dev_priv->drm,
> -				"Payload credit not available\n");
> +		if (!wait_for_payload_credits(dev_priv, dsi_trans, 1))
>  			return false;
> -		}
> 
>  		for (j = 0; j < min_t(u32, len - i, 4); j++)
>  			tmp |= *data++ << 8 * j;
> @@ -155,15 +158,10 @@ static int dsi_send_pkt_hdr(struct intel_dsi_host
> *host,
>  	struct drm_i915_private *dev_priv = to_i915(intel_dsi-
> >base.base.dev);
>  	enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
>  	u32 tmp;
> -	int free_credits;
> 
>  	/* check if header credit available */
> -	free_credits = header_credits_available(dev_priv, dsi_trans);
> -	if (free_credits < 1) {
> -		drm_err(&dev_priv->drm,
> -			"send pkt header failed, not enough hdr credits\n");
> +	if (!wait_for_header_credits(dev_priv, dsi_trans, 1))
>  		return -1;
> -	}
> 
>  	tmp = intel_de_read(dev_priv, DSI_CMD_TXHDR(dsi_trans));
> 
> --
> 2.17.1