Re: [PATCH 4/4] drm/i915: Get HW state changes required for DSI port C

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sun, 07 Dec 2014, Gaurav K Singh <gaurav.k.singh@intel.com> wrote:
> Due to some hardware limitations, 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.

"due to some hardware limitations" is awfully vague. The same code will
be used on many platforms; I doubt this applies to all of them. Is there
a workaround name for this?

BR,
Jani.

>
> Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dsi.c |   21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 215d004..0334c4d 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -398,8 +398,9 @@ 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);
>  	enum intel_display_power_domain power_domain;
> -	u32 port_ctl, func;
> +	u32 dsi_status, func;
>  	enum port port;
>  
>  	DRM_DEBUG_KMS("\n");
> @@ -409,13 +410,23 @@ 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));
>  
> -		if ((port_ctl & DPI_ENABLE) || (func & CMD_MODE_DATA_WIDTH_MASK)) {
> +		/* Due to some hardware limitations, 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 (port == PORT_C)
> +			dsi_status = I915_READ(PIPECONF(PIPE_B)) &
> +							PIPECONF_ENABLE;
> +		else
> +			dsi_status = I915_READ(MIPI_PORT_CTRL(port)) &
> +							DPI_ENABLE;
> +
> +		if (dsi_status || (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
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