Re: [PATCH/RFC 06/15] drm: bridge: thc63: Report input bus mode through bridge timings

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

On Sat, Mar 09, 2019 at 12:24:08PM +0100, Jacopo Mondi wrote:
> On Fri, Mar 08, 2019 at 08:00:28PM +0200, Laurent Pinchart wrote:
> > On Fri, Mar 08, 2019 at 06:32:59PM +0100, Jacopo Mondi wrote:
> >> On Thu, Mar 07, 2019 at 01:23:36AM +0200, Laurent Pinchart wrote:
> >>> Set a drm_bridge_timings in the drm_bridge, and use it to report the
> >>> input bus mode (single-link or dual-link). The other fields of the
> >>> timings structure are kept to 0 as they do not apply to LVDS buses.
> >>>
> >>> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >>> ---
> >>>  drivers/gpu/drm/bridge/thc63lvd1024.c | 46 ++++++++++++++++++++-------
> >>>  1 file changed, 35 insertions(+), 11 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
> >>> index b083a740565c..206b0af5e154 100644
> >>> --- a/drivers/gpu/drm/bridge/thc63lvd1024.c
> >>> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
> >>> @@ -31,6 +31,8 @@ struct thc63_dev {
> >>>
> >>>  	struct drm_bridge bridge;
> >>>  	struct drm_bridge *next;
> >>> +
> >>> +	struct drm_bridge_timings timings;
> >>>  };
> >>>
> >>>  static inline struct thc63_dev *to_thc63(struct drm_bridge *bridge)
> >>> @@ -48,15 +50,28 @@ static int thc63_attach(struct drm_bridge *bridge)
> >>>  static enum drm_mode_status thc63_mode_valid(struct drm_bridge *bridge,
> >>>  					const struct drm_display_mode *mode)
> >>>  {
> >>> +	struct thc63_dev *thc63 = to_thc63(bridge);
> >>> +	unsigned int min_freq;
> >>> +	unsigned int max_freq;
> >>> +
> >>>  	/*
> >>> -	 * The THC63LVD1024 clock frequency range is 8 to 135 MHz in single-in
> >>> -	 * mode. Note that the limits are different in dual-in, single-out mode,
> >>> -	 * and will need to be adjusted accordingly.
> >>> +	 * The THC63LVD1024 pixel rate range is 8 to 135 MHz in all modes but
> >>> +	 * dual-in, single-out where it is 40 to 150 MHz. As dual-in, dual-out
> >>> +	 * isn't supported by the driver yet, simply derive the limits from the
> >>> +	 * input mode.
> >>>  	 */
> >>> -	if (mode->clock < 8000)
> >>> +	if (thc63->timings.dual_link) {
> >>> +		min_freq = 40000;
> >>> +		max_freq = 150000;
> >>> +	} else {
> >>> +		min_freq = 8000;
> >>> +		max_freq = 135000;
> >>> +	}
> >>> +
> >>> +	if (mode->clock < min_freq)
> >>>  		return MODE_CLOCK_LOW;
> >>>
> >>> -	if (mode->clock > 135000)
> >>> +	if (mode->clock > max_freq)
> >>>  		return MODE_CLOCK_HIGH;
> >>>
> >>>  	return MODE_OK;
> >>> @@ -101,19 +116,19 @@ static const struct drm_bridge_funcs thc63_bridge_func = {
> >>>
> >>>  static int thc63_parse_dt(struct thc63_dev *thc63)
> >>>  {
> >>> -	struct device_node *thc63_out;
> >>> +	struct device_node *endpoint;
> >>>  	struct device_node *remote;
> >>>
> >>> -	thc63_out = of_graph_get_endpoint_by_regs(thc63->dev->of_node,
> >>> -						  THC63_RGB_OUT0, -1);
> >>> -	if (!thc63_out) {
> >>> +	endpoint = of_graph_get_endpoint_by_regs(thc63->dev->of_node,
> >>> +						 THC63_RGB_OUT0, -1);
> >>> +	if (!endpoint) {
> >>>  		dev_err(thc63->dev, "Missing endpoint in port@%u\n",
> >>>  			THC63_RGB_OUT0);
> >>>  		return -ENODEV;
> >>>  	}
> >>>
> >>> -	remote = of_graph_get_remote_port_parent(thc63_out);
> >>> -	of_node_put(thc63_out);
> >>> +	remote = of_graph_get_remote_port_parent(endpoint);
> >>> +	of_node_put(endpoint);
> >>>  	if (!remote) {
> >>>  		dev_err(thc63->dev, "Endpoint in port@%u unconnected\n",
> >>>  			THC63_RGB_OUT0);
> >>> @@ -132,6 +147,14 @@ static int thc63_parse_dt(struct thc63_dev *thc63)
> >>>  	if (!thc63->next)
> >>>  		return -EPROBE_DEFER;
> >>>
> >>> +	endpoint = of_graph_get_endpoint_by_regs(thc63->dev->of_node,
> >>> +						 THC63_LVDS_IN1, -1);
> >>> +	of_node_put(endpoint);
> >>> +
> >>
> >> Should you check if endpoint is enabled?
> >
> > Can endpoints be disabled ?
> 
> I meant the remote port parent, sorry about that.

Strictly speaking, you're right. I don't know if there's a practical use
for this, but I'll fix that in v2.

> >> By the way, this seems to me works properly, as in [12/15] if skip
> >> creation of the LVDS1 encoder if it is operating in dual link mode.
> >> Without that, we would hit again the issue of matching on device
> >> nodes, as the same bridge would be attached twice, am I wrong?
> >>
> >> I feel we've been there already :)
> >> https://lkml.org/lkml/2018/3/20/341
> >>
> >> and it is not just an issue on matching on endpoints, it's that the
> >> drm bridge itself that would need to handle multiple attach/detaches..
> >
> > Correct. Thanks to 12/15 we don't need this yet :-)
> >
> >>> +	thc63->timings.dual_link = endpoint != NULL;
> >>> +	dev_dbg(thc63->dev, "operating in %s-link mode\n",
> >>> +		thc63->timings.dual_link ? "dual" : "single");
> >>> +
> >>>  	return 0;
> >>>  }
> >>>
> >>> @@ -188,6 +211,7 @@ static int thc63_probe(struct platform_device *pdev)
> >>>  	thc63->bridge.driver_private = thc63;
> >>>  	thc63->bridge.of_node = pdev->dev.of_node;
> >>>  	thc63->bridge.funcs = &thc63_bridge_func;
> >>> +	thc63->bridge.timings = &thc63->timings;
> >>>
> >>>  	drm_bridge_add(&thc63->bridge);
> >>>

-- 
Regards,

Laurent Pinchart