[Intel-gfx] [PATCH v8 05/38] drm/i915/icl: Wait for header/payload credits release

[Madhav Chauhan]

On 10/30/2018 5:26 PM, Jani Nikula wrote:
> From: Madhav Chauhan <madhav.chauhan at intel.com>
>
> Driver needs payload/header credits for sending any command
> and data over DSI link. These credits are released once command
> or data sent to link. This patch adds functions to wait for releasing
> of payload and header credits.
>
> As per BSPEC, driver needs to ensure that all of commands/data
> has been dispatched to panel before the transcoder is enabled.
> This patch implement those steps i.e. sending NOP DCS command,
> wait for header/payload credit to be released etc.
>
> v2 by Jani:
>   - squash the credit wait helpers patch with the first user
>   - pass dev_priv to the credit wait helpers
>   - bikeshed credit helper names
>   - wait for *at least* the current maximum number of credits
>   - indentation fix
>   - add helpers for credits available

This is good optimization, thanks. Looks good.

Regards,
Madhav

>
> Signed-off-by: Madhav Chauhan <madhav.chauhan at intel.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>   drivers/gpu/drm/i915/icl_dsi.c | 74 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 74 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/icl_dsi.c b/drivers/gpu/drm/i915/icl_dsi.c
> index d9c91001f107..0f0447b6b1be 100644
> --- a/drivers/gpu/drm/i915/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/icl_dsi.c
> @@ -28,6 +28,36 @@
>   #include <drm/drm_mipi_dsi.h>
>   #include "intel_dsi.h"
>   
> +static inline int header_credits_available(struct drm_i915_private *dev_priv,
> +					   enum transcoder dsi_trans)
> +{
> +	return (I915_READ(DSI_CMD_TXCTL(dsi_trans)) & FREE_HEADER_CREDIT_MASK)
> +		>> FREE_HEADER_CREDIT_SHIFT;
> +}
> +
> +static inline int payload_credits_available(struct drm_i915_private *dev_priv,
> +					    enum transcoder dsi_trans)
> +{
> +	return (I915_READ(DSI_CMD_TXCTL(dsi_trans)) & FREE_PLOAD_CREDIT_MASK)
> +		>> FREE_PLOAD_CREDIT_SHIFT;
> +}
> +
> +static void wait_for_header_credits(struct drm_i915_private *dev_priv,
> +				    enum transcoder dsi_trans)
> +{
> +	if (wait_for_us(header_credits_available(dev_priv, dsi_trans) >=
> +			MAX_HEADER_CREDIT, 100))
> +		DRM_ERROR("DSI header credits not released\n");
> +}
> +
> +static void wait_for_payload_credits(struct drm_i915_private *dev_priv,
> +				     enum transcoder dsi_trans)
> +{
> +	if (wait_for_us(payload_credits_available(dev_priv, dsi_trans) >=
> +			MAX_PLOAD_CREDIT, 100))
> +		DRM_ERROR("DSI payload credits not released\n");
> +}
> +
>   static enum transcoder dsi_port_to_transcoder(enum port port)
>   {
>   	if (port == PORT_A)
> @@ -36,6 +66,47 @@ static enum transcoder dsi_port_to_transcoder(enum port port)
>   		return TRANSCODER_DSI_1;
>   }
>   
> +static void wait_for_cmds_dispatched_to_panel(struct intel_encoder *encoder)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +	struct mipi_dsi_device *dsi;
> +	enum port port;
> +	enum transcoder dsi_trans;
> +	int ret;
> +
> +	/* 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);
> +	}
> +
> +	/* send nop DCS command */
> +	for_each_dsi_port(port, intel_dsi->ports) {
> +		dsi = intel_dsi->dsi_hosts[port]->device;
> +		dsi->mode_flags |= MIPI_DSI_MODE_LPM;
> +		dsi->channel = 0;
> +		ret = mipi_dsi_dcs_nop(dsi);
> +		if (ret < 0)
> +			DRM_ERROR("error sending DCS NOP command\n");
> +	}
> +
> +	/* 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 LP TX in progress bit to be cleared */
> +	for_each_dsi_port(port, intel_dsi->ports) {
> +		dsi_trans = dsi_port_to_transcoder(port);
> +		if (wait_for_us(!(I915_READ(DSI_LP_MSG(dsi_trans)) &
> +				  LPTX_IN_PROGRESS), 20))
> +			DRM_ERROR("LPTX bit not cleared\n");
> +	}
> +}
> +
>   static void dsi_program_swing_and_deemphasis(struct intel_encoder *encoder)
>   {
>   	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> @@ -671,6 +742,9 @@ static void gen11_dsi_powerup_panel(struct intel_encoder *encoder)
>   	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
>   	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
>   	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DISPLAY_ON);
> +
> +	/* ensure all panel commands dispatched before enabling transcoder */
> +	wait_for_cmds_dispatched_to_panel(encoder);
>   }
>   
>   static void __attribute__((unused))