Re: [Intel-gfx] [v4 4/7] drm/i915/dsi: refine send MIPI DCS command sequence

["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 4/7] drm/i915/dsi: refine send MIPI DCS command sequence
> 
> According to chapter "Sending Commands to the Panel" in bspec #29738 and
> #49188. If driver try to send DCS long pakcet, we have to program TX payload
> register at first. And configure TX header HW register later.
> DSC long packet would not be sent properly if we don't follow this sequence.
> 
> 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 | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c
> b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 1780830d9909..60413bbf565f 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -1807,11 +1807,6 @@ static ssize_t gen11_dsi_host_transfer(struct
> mipi_dsi_host *host,
>  	if (msg->flags & MIPI_DSI_MSG_USE_LPM)
>  		enable_lpdt = true;
> 
> -	/* send packet header */
> -	ret  = dsi_send_pkt_hdr(intel_dsi_host, dsi_pkt, enable_lpdt);
> -	if (ret < 0)
> -		return ret;
> -
>  	/* only long packet contains payload */
>  	if (mipi_dsi_packet_format_is_long(msg->type)) {
>  		ret = dsi_send_pkt_payld(intel_dsi_host, dsi_pkt); @@ -
> 1819,6 +1814,11 @@ static ssize_t gen11_dsi_host_transfer(struct
> mipi_dsi_host *host,
>  			return ret;
>  	}
> 
> +	/* send packet header */
> +	ret  = dsi_send_pkt_hdr(intel_dsi_host, dsi_pkt, enable_lpdt);
> +	if (ret < 0)
> +		return ret;
> +
>  	//TODO: add payload receive code if needed
> 
>  	ret = sizeof(dsi_pkt.header) + dsi_pkt.payload_length;
> --
> 2.17.1