On Tue, May 9, 2023 at 10:14 AM Marek Vasut <marex@xxxxxxx> wrote:
>
> On 5/8/23 07:57, Liu Ying wrote:
> > The single LCDIF embedded in i.MX93 SoC may drive multiple displays
> > simultaneously. Look at LCDIF output port's remote port parents to
> > find all enabled first bridges. Add an encoder for each found bridge
> > and attach the bridge to the encoder. This is a preparation for
> > adding i.MX93 LCDIF support.
> >
> > Tested-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > Acked-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > ---
> > v4->v5:
> > * Rebase upon v6.4-rc1 and resolve a trivial conflict.
> > * Add Alexander's A-b and T-b tags.
> >
> > v3->v4:
> > * Improve warning message when ignoring invalid LCDIF OF endpoint ids.
> > (Alexander)
> >
> > v2->v3:
> > * No change.
> >
> > v1->v2:
> > * Split from patch 2/2 in v1. (Marek, Alexander)
> > * Drop '!remote ||' from lcdif_attach_bridge(). (Lothar)
> > * Drop unneeded 'bridges' member from lcdif_drm_private structure.
> >
> > drivers/gpu/drm/mxsfb/lcdif_drv.c | 68 +++++++++++++++++++++++++++----
> > drivers/gpu/drm/mxsfb/lcdif_drv.h | 4 +-
> > drivers/gpu/drm/mxsfb/lcdif_kms.c | 21 ++--------
> > 3 files changed, 66 insertions(+), 27 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > index e816f87828fb..cf27b63b1899 100644
> > --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > @@ -9,13 +9,16 @@
> > #include <linux/dma-mapping.h>
> > #include <linux/io.h>
> > #include <linux/module.h>
> > +#include <linux/of.h>
> > #include <linux/of_device.h>
> > +#include <linux/of_graph.h>
> > #include <linux/platform_device.h>
> > #include <linux/pm_runtime.h>
> >
> > #include <drm/drm_atomic_helper.h>
> > #include <drm/drm_bridge.h>
> > #include <drm/drm_drv.h>
> > +#include <drm/drm_encoder.h>
> > #include <drm/drm_fbdev_dma.h>
> > #include <drm/drm_gem_dma_helper.h>
> > #include <drm/drm_gem_framebuffer_helper.h>
> > @@ -38,19 +41,68 @@ static const struct drm_mode_config_helper_funcs lcdif_mode_config_helpers = {
> > .atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
> > };
> >
> > +static const struct drm_encoder_funcs lcdif_encoder_funcs = {
> > + .destroy = drm_encoder_cleanup,
> > +};
> > +
> > static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
> > {
> > - struct drm_device *drm = lcdif->drm;
> > + struct device *dev = lcdif->drm->dev;
> > + struct device_node *ep;
> > struct drm_bridge *bridge;
> > int ret;
> >
> > - bridge = devm_drm_of_get_bridge(drm->dev, drm->dev->of_node, 0, 0);
> > - if (IS_ERR(bridge))
> > - return PTR_ERR(bridge);
> > -
> > - ret = drm_bridge_attach(&lcdif->encoder, bridge, NULL, 0);
> > - if (ret)
> > - return dev_err_probe(drm->dev, ret, "Failed to attach bridge\n");
> > + for_each_endpoint_of_node(dev->of_node, ep) {
> > + struct device_node *remote;
> > + struct of_endpoint of_ep;
> > + struct drm_encoder *encoder;
> > +
> > + remote = of_graph_get_remote_port_parent(ep);
> > + if (!of_device_is_available(remote)) {
> > + of_node_put(remote);
> > + continue;
> > + }
> > + of_node_put(remote);
> > +
> > + ret = of_graph_parse_endpoint(ep, &of_ep);
> > + if (ret < 0) {
> > + dev_err(dev, "Failed to parse endpoint %pOF\n", ep);
> > + of_node_put(ep);
> > + return ret;
> > + }
> > +
> > + if (of_ep.id >= MAX_DISPLAYS) {
>
> Can we make the maximum number of displays, or really bridge, specific
> to IP instance instead (1 for mx8mp, 3 for mx93) ? If so, then I think
> we need to track a list of bridges in some linked list or some such
> dynamic structure, which would allow us to get rid of MAX_DISPLAYS macro.
I don't think we need to track bridges, since bridges can be found
through connector's encoder, like lcdif_crtc_atomic_check() does
in patch 4/6. Instead, MAX_DISPLAYS and the encoder member
in struct lcdif_drm_private can be dropped if we call devm_kzalloc()
to allocate encoders in this function.
>
> > + dev_warn(dev, "ingoring invalid endpoint id %u\n", of_ep.id);
>
> s@ingoring@ignoring@
Right. But the endpoint id check is not mandatory and is better
to be dropped together with MAX_DISPLAYS. I mean the driver
doesn't have to validate the endpoint id set in device tree.
Regards,
Liu Ying
>
> [...]
