On Wed, 2023-02-15 at 08:54 +0100, Alexander Stein wrote:
> Hi Liu,
Hi Alexander,
>
> thanks for the update.
Thanks for the review.
>
> Am Montag, 13. Februar 2023, 09:56:11 CET schrieb Liu Ying:
> > 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.
> >
> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > ---
> > 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
> > b5b9a8e273c6..eb6c265fa2fe 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_generic.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);
>
> Is it possible for remote to be NULL?
Yes. But, no worries. Lothar said the check for '!remote' is not
needed in v1 comment because of_device_is_available() checks that.
>
> > + 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) {
> > + dev_warn(dev, "invalid endpoint id %u\n",
>
> of_ep.id);
>
> I would write
> dev_warn(dev, "ignoring invalid endpoint id %u\n", of_ep.id);
> just because the parsing continues but this one is skipped.
Ok, will do that in next version.
>
> > + continue;
> > + }
> > +
> > + bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0,
>
> of_ep.id);
> > + if (IS_ERR(bridge)) {
> > + of_node_put(ep);
> > + return dev_err_probe(dev, PTR_ERR(bridge),
> > + "Failed to get bridge
>
> for endpoint%u\n",
> > + of_ep.id);
> > + }
> > +
> > + encoder = &lcdif->encoders[of_ep.id];
> > + encoder->possible_crtcs = drm_crtc_mask(&lcdif->crtc);
> > + ret = drm_encoder_init(lcdif->drm, encoder,
>
> &lcdif_encoder_funcs,
> > + DRM_MODE_ENCODER_NONE, NULL);
> > + if (ret) {
> > + dev_err(dev, "Failed to initialize encoder for
>
> endpoint%u: %d\n",
> > + of_ep.id, ret);
> > + of_node_put(ep);
> > + return ret;
> > + }
> > +
> > + ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> > + if (ret) {
> > + of_node_put(ep);
> > + return dev_err_probe(dev, ret,
> > + "Failed to attach
>
> bridge for endpoint%u\n",
> > + of_ep.id);
> > + }
>
> Admittedly I'm not used to the drm API, but do we need to some manual
> cleanup/
> revert if some endpoints is e.g. deferred, but previous endpoints
> already have
> been successfully added? e.g. endpoint 0 is added, but adding
> endpoint 1
> fails.
I think the bailout path is safe, because
drm_mode_config_init_release() is called as the managed release action
added through drm_mode_config_init(). drm_mode_config_cleanup() would
clean things up.
Regards,
Liu Ying
