[Intel-gfx] [PATCH 4/4] drm/i915: Software workaround for getting the HW status of DSI Port C on BYT

[Jani Nikula]

On Tue, 09 Dec 2014, Gaurav K Singh <gaurav.k.singh at intel.com> wrote:
> Due to hardware limitations on BYT, MIPI Port C DPI Enable bit
> does not get set. To check whether DSI Port C was enabled in BIOS,
> check the Pipe B enable bit for DSI Port C. In hardware, DSI Port C
> is linked with Pipe B.
>
> v2: Addressed review comments of Jani, Nikula
>     - Used platform checks for this software workaround for BYT
>
> Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>

I'll take your word for the hardware limitation itself, otherwise

Reviewed-by: Jani Nikula <jani.nikula at intel.com>


> ---
>  drivers/gpu/drm/i915/intel_dsi.c |   22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 215d004..42b6d6f 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -398,8 +398,10 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
>  				   enum pipe *pipe)
>  {
>  	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
> +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	struct drm_device *dev = encoder->base.dev;
>  	enum intel_display_power_domain power_domain;
> -	u32 port_ctl, func;
> +	u32 dpi_enabled, func;
>  	enum port port;
>  
>  	DRM_DEBUG_KMS("\n");
> @@ -409,13 +411,23 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
>  		return false;
>  
>  	/* XXX: this only works for one DSI output */
> -	for_each_dsi_port(port, (1 << PORT_A) | (1 << PORT_C)) {
> -		port_ctl = I915_READ(MIPI_PORT_CTRL(port));
> +	for_each_dsi_port(port, intel_dsi->ports) {
>  		func = I915_READ(MIPI_DSI_FUNC_PRG(port));
> +		dpi_enabled = I915_READ(MIPI_PORT_CTRL(port)) &
> +							DPI_ENABLE;
> +
> +		/* Due to some hardware limitations on BYT, MIPI Port C DPI
> +		 * Enable bit does not get set. To check whether DSI Port C
> +		 * was enabled in BIOS, check the Pipe B enable bit
> +		 */
> +		if (IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev) &&
> +		    (port == PORT_C))
> +			dpi_enabled = I915_READ(PIPECONF(PIPE_B)) &
> +							PIPECONF_ENABLE;
>  
> -		if ((port_ctl & DPI_ENABLE) || (func & CMD_MODE_DATA_WIDTH_MASK)) {
> +		if (dpi_enabled || (func & CMD_MODE_DATA_WIDTH_MASK)) {
>  			if (I915_READ(MIPI_DEVICE_READY(port)) & DEVICE_READY) {
> -				*pipe = port == PORT_A ? PIPE_A : PIPE_C;
> +				*pipe = port == PORT_A ? PIPE_A : PIPE_B;
>  				return true;
>  			}
>  		}
> -- 
> 1.7.9.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center