Hello Aradhya, Tomi,
On 28/05/25 17:55, Aradhya Bhatia wrote:
From: Aradhya Bhatia <a-bhat...@ti.com>
The AM62x and AM62Px SoCs feature 2 OLDI TXes each, which makes it
possible to connect them in dual-link or cloned single-link OLDI display
modes. The current OLDI support in tidss_dispc.c can only support for
a single OLDI TX, connected to a VP and doesn't really support
configuration of OLDIs in the other modes. The current OLDI support in
tidss_dispc.c also works on the principle that the OLDI output can only
be served by one, and only one, DSS video-port. This isn't the case in
the AM62Px SoC, where there are 2 DSS controllers present that share the
OLDI TXes.
[...]
+}
+
+int tidss_oldi_init(struct tidss_device *tidss)
+{
+ struct tidss_oldi *oldi;
+ struct device_node *child;
+ struct drm_bridge *bridge;
+ u32 parent_vp, oldi_instance;
+ int companion_instance = -1;
+ enum tidss_oldi_link_type link_type = OLDI_MODE_UNSUPPORTED;
+ struct device_node *oldi_parent;
+ int ret = 0;
+
+ tidss->num_oldis = 0;
+
+ oldi_parent = of_get_child_by_name(tidss->dev->of_node,
"oldi-transmitters");
+ if (!oldi_parent)
+ /* Return gracefully */
+ return 0;
+
+ for_each_available_child_of_node(oldi_parent, child) {
+ ret = get_parent_dss_vp(child, &parent_vp);
+ if (ret) {
+ if (ret == -ENODEV) {
+ /*
+ * ENODEV means that this particular OLDI node
+ * is not connected with the DSS, which is not
+ * a harmful case. There could be another OLDI
+ * which may still be connected.
+ * Continue to search for that.
+ */
+ ret = 0;
+ continue;
+ }
+ goto err_put_node;
+ }
+
+ ret = of_property_read_u32(child, "reg", &oldi_instance);
+ if (ret)
+ goto err_put_node;
+
+ /*
+ * Now that it's confirmed that OLDI is connected with DSS,
+ * let's continue getting the OLDI sinks ahead and other OLDI
+ * properties.
+ */
+ bridge = devm_drm_of_get_bridge(tidss->dev, child,
+ OLDI_OUTPUT_PORT, 0);
+ if (IS_ERR(bridge)) {
+ /*
+ * Either there was no OLDI sink in the devicetree, or
+ * the OLDI sink has not been added yet. In any case,
+ * return.
+ * We don't want to have an OLDI node connected to DSS
+ * but not to any sink.
+ */
+ ret = dev_err_probe(tidss->dev, PTR_ERR(bridge),
+ "no panel/bridge for OLDI%u.\n",
+ oldi_instance);
+ goto err_put_node;
+ }
+
+ link_type = get_oldi_mode(child, &companion_instance);
+ if (link_type == OLDI_MODE_UNSUPPORTED) {
+ ret = dev_err_probe(tidss->dev, -EINVAL,
+ "OLDI%u: Unsupported OLDI
connection.\n",
+ oldi_instance);
+ goto err_put_node;
+ } else if ((link_type == OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK)
||
+ (link_type == OLDI_MODE_CLONE_SINGLE_LINK)) {
+ /*
+ * The OLDI driver cannot support OLDI clone mode
+ * properly at present.
+ * The clone mode requires 2 working encoder-bridge
+ * pipelines, generating from the same crtc. The DRM
+ * framework does not support this at present. If
+ * there were to be, say, 2 OLDI sink bridges each
+ * connected to an OLDI TXes, they couldn't both be
+ * supported simultaneously.
+ * This driver still has some code pertaining to OLDI
+ * clone mode configuration in DSS hardware for future,
+ * when there is a better infrastructure in the DRM
+ * framework to support 2 encoder-bridge pipelines
+ * simultaneously.
+ * Till that time, this driver shall error out if it
+ * detects a clone mode configuration.
+ */
+ ret = dev_err_probe(tidss->dev, -EOPNOTSUPP,
+ "The OLDI driver does not support Clone
Mode at present.\n");
+ goto err_put_node;
+ } else if (link_type == OLDI_MODE_SECONDARY_DUAL_LINK) {
+ /*
+ * This is the secondary OLDI node, which serves as a
+ * companion to the primary OLDI, when it is configured
+ * for the dual-link mode. Since the primary OLDI will
+ * be a part of bridge chain, no need to put this one
+ * too. Continue onto the next OLDI node.
+ */
+ continue;
+ }
+
+ oldi = devm_kzalloc(tidss->dev, sizeof(*oldi), GFP_KERNEL);
I think this needs to be changed to devm_drm_bridge_alloc() to get rid
of the kernel warning. I am seeing WARNING in OLDI like:
[ 10.198109] WARNING: lib/refcount.c:25 at
refcount_warn_saturate+0x120/0x144, CPU#0: kworker/u16:0/12
[ 10.198140] Modules linked in: snd_soc_simple_card mux_gpio
snd_soc_simple_card_utils panel_simple cdns3_ti display_connector
snd_soc_davinci_mcasp phy_can_transceiver k3_j72xx_bandgap tps6594_i2c tps6
[ 10.198310] CPU: 0 UID: 0 PID: 12 Comm: kworker/u16:0 Not tainted
6.16.0-rc3-next-20250627-00046-ga876218600d6 #197 PREEMPT
[ 10.198321] Hardware name: Texas Instruments J722S EVM (DT)
[ 10.198327] Workqueue: events_unbound deferred_probe_work_func
[ 10.198344] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS
BTYPE=--)
[ 10.198352] pc : refcount_warn_saturate+0x120/0x144
[ 10.198359] lr : refcount_warn_saturate+0x120/0x144
[ 10.198365] sp : ffff800082fa3a30
[ 10.198368] x29: ffff800082fa3a30 x28: 0000000000000000 x27:
0000000000000000
[ 10.198377] x26: 0000000000000004 x25: 0000000000000001 x24:
ffff80007b1edf48
[ 10.198386] x23: ffff000806fa0000 x22: ffff00080c466800 x21:
ffff00094701ec20
[ 10.198395] x20: ffff00080f9cec80 x19: ffff00080f9cec90 x18:
fffffffffffe99f8
[ 10.198404] x17: ffff8008c4f5e000 x16: ffff800080000000 x15:
0000000000000002
[ 10.198414] x14: ffff0008001dc680 x13: 0000000000000021 x12:
0000000013cbce01
[ 10.198423] x11: 00000005cc209839 x10: ffff000946f68a40 x9 :
ffff0008001dc680
[ 10.198433] x8 : 0000000000000000 x7 : ffff0008001dc680 x6 :
0000000000000002
[ 10.198441] x5 : 0000000000000400 x4 : 0000000000000400 x3 :
0000000013cbce01
[ 10.198450] x2 : 0000000000000000 x1 : 0000000000000000 x0 :
ffff0008001dc600
[ 10.198459] Call trace:
[ 10.198464] refcount_warn_saturate+0x120/0x144 (P)
[ 10.198473] drm_bridge_add+0xec/0xf0 [drm]
[ 10.198733] tidss_oldi_init+0x2e0/0x434 [tidss]
[ 10.198759] tidss_probe+0x1a4/0x2e0 [tidss]
[ 10.198774] platform_probe+0x68/0xc4
[ 10.198786] really_probe+0xbc/0x29c
[ 10.198798] __driver_probe_device+0x78/0x12c
[ 10.198808] driver_probe_device+0xd8/0x15c
[ 10.198817] __device_attach_driver+0xb8/0x134
oldi = devm_drm_bridge_alloc(tidss->dev, struct tidss_oldi, bridge,
&tidss_oldi_bridge_funcs);
I am posting a fix patch for this since now its merged to linux-next.
Thanks,
Jayesh
[...]
