Re: [PATCH v2] drm/bridge: nwl-dsi: Get MIPI DSI controller and PHY ready in ->mode_set()

[Liu Ying]

Hi Neil,

On Thu, 2021-04-22 at 10:48 +0200, Neil Armstrong wrote:
> Hi,
> 
> On 22/04/2021 07:14, Liu Ying wrote:
> > Some MIPI DSI panel drivers like 'raydium,rm68200' send
> > MIPI_DCS_SET_DISPLAY_ON commands in panel_funcs->prepare(), which
> > requires the MIPI DSI controller and PHY to be ready beforehand.
> > Without this patch, the nwl-dsi driver gets the MIPI DSI controller
> > and PHY ready in bridge_funcs->pre_enable(), which happens after
> > the panel_funcs->prepare(). So, this patch shifts the bridge operation
> > ealier from bridge_funcs->pre_enable() to bridge_funcs->mode_set().
> 
> This makes sense, this is how we do on the synopsys dw mipi dsi driver.
> 
> > This way, more MIPI DSI panels can connect to this nwl-dsi bridge.
> > Care is taken to make sure bridge_funcs->mode_set()/atomic_disable()
> > are called in pairs, which includes removing a check on unchanged HS
> > clock rate and forcing a full modeset when only connector's DPMS is
> > brought out of "Off" status.
> 
> I would split the changes in multiple patches to clarify the changes.

Maybe, I can split this into the below 3 patches:
1) Remove a check on unchanged HS clock rate from ->mode_set().
2) Force a full modeset when only connector's DPMS is brought out of
"Off" status. This will be done in ->atomic_check() together with the
fixup for H/VSYNC polarities.
3) Shift the bridge operation as the last step.

I'll mention that 1) & 2) are needed by 3) in their commit message.

Does this split-up sound reasonable?

Thanks,
Liu Ying

> 
> Neil
> 
> > Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> > Cc: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> > Cc: Robert Foss <robert.foss@xxxxxxxxxx>
> > Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
> > Cc: Jonas Karlman <jonas@xxxxxxxxx>
> > Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
> > Cc: David Airlie <airlied@xxxxxxxx>
> > Cc: Daniel Vetter <daniel@xxxxxxxx>
> > Cc: Guido Günther <agx@xxxxxxxxxxx>
> > Cc: Robert Chiras <robert.chiras@xxxxxxx>
> > Cc: NXP Linux Team <linux-imx@xxxxxxx>
> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > ---
> > v1->v2:
> > * Fix commit message typo - s/unchange/unchanged/
> > 
> >  drivers/gpu/drm/bridge/nwl-dsi.c | 86 +++++++++++++++++++++-------------------
> >  1 file changed, 46 insertions(+), 40 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
> > index be6bfc5..229f0b1 100644
> > --- a/drivers/gpu/drm/bridge/nwl-dsi.c
> > +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/sys_soc.h>
> >  #include <linux/time64.h>
> >  
> > +#include <drm/drm_atomic_state_helper.h>
> >  #include <drm/drm_bridge.h>
> >  #include <drm/drm_mipi_dsi.h>
> >  #include <drm/drm_of.h>
> > @@ -661,7 +662,7 @@ static irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> >  	return IRQ_HANDLED;
> >  }
> >  
> > -static int nwl_dsi_enable(struct nwl_dsi *dsi)
> > +static int nwl_dsi_mode_set(struct nwl_dsi *dsi)
> >  {
> >  	struct device *dev = dsi->dev;
> >  	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> > @@ -748,7 +749,9 @@ static int nwl_dsi_disable(struct nwl_dsi *dsi)
> >  	return 0;
> >  }
> >  
> > -static void nwl_dsi_bridge_disable(struct drm_bridge *bridge)
> > +static void
> > +nwl_dsi_bridge_atomic_disable(struct drm_bridge *bridge,
> > +			      struct drm_bridge_state *old_bridge_state)
> >  {
> >  	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> >  	int ret;
> > @@ -809,17 +812,6 @@ static int nwl_dsi_get_dphy_params(struct nwl_dsi *dsi,
> >  	return 0;
> >  }
> >  
> > -static bool nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
> > -				      const struct drm_display_mode *mode,
> > -				      struct drm_display_mode *adjusted_mode)
> > -{
> > -	/* At least LCDIF + NWL needs active high sync */
> > -	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > -	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> > -
> > -	return true;
> > -}
> > -
> >  static enum drm_mode_status
> >  nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> >  			  const struct drm_display_info *info,
> > @@ -837,6 +829,29 @@ nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> >  	return MODE_OK;
> >  }
> >  
> > +static int nwl_dsi_bridge_atomic_check(struct drm_bridge *bridge,
> > +				       struct drm_bridge_state *bridge_state,
> > +				       struct drm_crtc_state *crtc_state,
> > +				       struct drm_connector_state *conn_state)
> > +{
> > +	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
> > +
> > +	/* At least LCDIF + NWL needs active high sync */
> > +	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> > +
> > +	/*
> > +	 * Do a full modeset if crtc_state->active is changed to be true.
> > +	 * This ensures our ->mode_set() is called to get the DSI controller
> > +	 * and the PHY ready to send DCS commands, when only the connector's
> > +	 * DPMS is brought out of "Off" status.
> > +	 */
> > +	if (crtc_state->active_changed && crtc_state->active)
> > +		crtc_state->mode_changed = true;
> > +
> > +	return 0;
> > +}
> > +
> >  static void
> >  nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> >  			const struct drm_display_mode *mode,
> > @@ -852,13 +867,6 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> >  	if (ret < 0)
> >  		return;
> >  
> > -	/*
> > -	 * If hs clock is unchanged, we're all good - all parameters are
> > -	 * derived from it atm.
> > -	 */
> > -	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
> > -		return;
> > -
> >  	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> >  	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> >  	/* Save the new desired phy config */
> > @@ -866,14 +874,8 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> >  
> >  	memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
> >  	drm_mode_debug_printmodeline(adjusted_mode);
> > -}
> >  
> > -static void nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> > -{
> > -	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> > -	int ret;
> > -
> > -	pm_runtime_get_sync(dsi->dev);
> > +	pm_runtime_get_sync(dev);
> >  
> >  	if (clk_prepare_enable(dsi->lcdif_clk) < 0)
> >  		return;
> > @@ -883,27 +885,29 @@ static void nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> >  	/* Step 1 from DSI reset-out instructions */
> >  	ret = reset_control_deassert(dsi->rst_pclk);
> >  	if (ret < 0) {
> > -		DRM_DEV_ERROR(dsi->dev, "Failed to deassert PCLK: %d\n", ret);
> > +		DRM_DEV_ERROR(dev, "Failed to deassert PCLK: %d\n", ret);
> >  		return;
> >  	}
> >  
> >  	/* Step 2 from DSI reset-out instructions */
> > -	nwl_dsi_enable(dsi);
> > +	nwl_dsi_mode_set(dsi);
> >  
> >  	/* Step 3 from DSI reset-out instructions */
> >  	ret = reset_control_deassert(dsi->rst_esc);
> >  	if (ret < 0) {
> > -		DRM_DEV_ERROR(dsi->dev, "Failed to deassert ESC: %d\n", ret);
> > +		DRM_DEV_ERROR(dev, "Failed to deassert ESC: %d\n", ret);
> >  		return;
> >  	}
> >  	ret = reset_control_deassert(dsi->rst_byte);
> >  	if (ret < 0) {
> > -		DRM_DEV_ERROR(dsi->dev, "Failed to deassert BYTE: %d\n", ret);
> > +		DRM_DEV_ERROR(dev, "Failed to deassert BYTE: %d\n", ret);
> >  		return;
> >  	}
> >  }
> >  
> > -static void nwl_dsi_bridge_enable(struct drm_bridge *bridge)
> > +static void
> > +nwl_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
> > +			     struct drm_bridge_state *old_bridge_state)
> >  {
> >  	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> >  	int ret;
> > @@ -948,14 +952,16 @@ static void nwl_dsi_bridge_detach(struct drm_bridge *bridge)
> >  }
> >  
> >  static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
> > -	.pre_enable = nwl_dsi_bridge_pre_enable,
> > -	.enable     = nwl_dsi_bridge_enable,
> > -	.disable    = nwl_dsi_bridge_disable,
> > -	.mode_fixup = nwl_dsi_bridge_mode_fixup,
> > -	.mode_set   = nwl_dsi_bridge_mode_set,
> > -	.mode_valid = nwl_dsi_bridge_mode_valid,
> > -	.attach	    = nwl_dsi_bridge_attach,
> > -	.detach	    = nwl_dsi_bridge_detach,
> > +	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
> > +	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
> > +	.atomic_reset		= drm_atomic_helper_bridge_reset,
> > +	.atomic_check		= nwl_dsi_bridge_atomic_check,
> > +	.atomic_enable		= nwl_dsi_bridge_atomic_enable,
> > +	.atomic_disable		= nwl_dsi_bridge_atomic_disable,
> > +	.mode_set		= nwl_dsi_bridge_mode_set,
> > +	.mode_valid		= nwl_dsi_bridge_mode_valid,
> > +	.attach			= nwl_dsi_bridge_attach,
> > +	.detach			= nwl_dsi_bridge_detach,
> >  };
> >  
> >  static int nwl_dsi_parse_dt(struct nwl_dsi *dsi)
> >