Hi, Dear u-boot lists, who can help answer my questions below about device_bind_common in drivers/core/device.c of u-boot? Thanks!

[Xiujun, Wang (CSW)]

1.
Now we are porting rproc diver from NxP to our own u-boot which is based on NXP's v2020.04 version, and we find that if we don't do any changes to the device_bind_common interface in drivers/core/device.c and the rproc driver doesn't work. Then if we add some codes(two red lines below) to the device_bind_common interface in drivers/core/device.c and the rproc driver works well.
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
static int device_bind_common(struct udevice *parent, const struct driver *drv,
                                                 const char *name, void *platdata,
                                                 ulong driver_data, ofnode node,
                                                 uint of_platdata_size, struct udevice **devp)
{
              struct udevice *dev;
              struct uclass *uc;
              int size, ret = 0;

              if (devp)
                             *devp = NULL;
              if (!name)
                             return -EINVAL;

              ret = uclass_get(drv->id, &uc);
              if (ret) {
                             debug("Missing uclass for driver %s\n", drv->name);
                             return ret;
              }

              dev = calloc(1, sizeof(struct udevice));
              if (!dev)
                             return -ENOMEM;

              INIT_LIST_HEAD(&dev->sibling_node);
              INIT_LIST_HEAD(&dev->child_head);
              INIT_LIST_HEAD(&dev->uclass_node);
#ifdef CONFIG_DEVRES
              INIT_LIST_HEAD(&dev->devres_head);
#endif
              dev->platdata = platdata;
              dev->driver_data = driver_data;
              dev->name = name;
              dev->node = node;
              dev->parent = parent;
              dev->driver = drv;
              dev->uclass = uc;

              dev->seq = -1;
              dev->req_seq = -1;
              if (CONFIG_IS_ENABLED(DM_SEQ_ALIAS) &&
                  (uc->uc_drv->flags & DM_UC_FLAG_SEQ_ALIAS)) {
                             /*
                             * Some devices, such as a SPI bus, I2C bus and serial ports
                             * are numbered using aliases.
                             *
                             * This is just a 'requested' sequence, and will be
                             * resolved (and ->seq updated) when the device is probed.
                             */
                             if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) {
                                           if (uc->uc_drv->name && ofnode_valid(node)){
                                                          dev_read_alias_seq(dev, &dev->req_seq);
                                                          if (strcmp(dev->name, "imx8mm-cm4") == 0)
                                                                        dev->req_seq = uclass_find_next_free_req_seq(drv->id);
                                           }
#if CONFIG_IS_ENABLED(OF_PRIOR_STAGE)
                                           if (dev->req_seq == -1)
                                                          dev->req_seq =
                                                                        uclass_find_next_free_req_seq(drv->id);
#endif
                             } else {
                                           dev->req_seq = uclass_find_next_free_req_seq(drv->id);
                             }

              }
......
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
My question is why I should add these two lines code.
Note: We have one node in our dts file below.
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
imx8mm-cm4 {
                             compatible = "fsl,imx8mm-cm4";
                             syscon = <&src>;
              };
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

2.
I notice that device_bind_common in drivers/core/device.c was changed as follows in v2021.04 version.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
static int device_bind_common(struct udevice *parent, const struct driver *drv,
                                                 const char *name, void *plat,
                                                 ulong driver_data, ofnode node,
                                                 uint of_plat_size, struct udevice **devp)
{
              struct udevice *dev;
              struct uclass *uc;
              int size, ret = 0;
              bool auto_seq = true;
              void *ptr;

              if (CONFIG_IS_ENABLED(OF_PLATDATA_NO_BIND))
                             return -ENOSYS;

              if (devp)
                             *devp = NULL;
              if (!name)
                             return -EINVAL;

              ret = uclass_get(drv->id, &uc);
              if (ret) {
                             dm_warn("Missing uclass for driver %s\n", drv->name);
                             return ret;
              }

              dev = calloc(1, sizeof(struct udevice));
              if (!dev)
                             return -ENOMEM;

              INIT_LIST_HEAD(&dev->sibling_node);
              INIT_LIST_HEAD(&dev->child_head);
              INIT_LIST_HEAD(&dev->uclass_node);
#if CONFIG_IS_ENABLED(DEVRES)
              INIT_LIST_HEAD(&dev->devres_head);
#endif
              dev_set_plat(dev, plat);
              dev->driver_data = driver_data;
              dev->name = name;
              dev_set_ofnode(dev, node);
              dev->parent = parent;
              dev->driver = drv;
              dev->uclass = uc;

              dev->seq_ = -1;
              if (CONFIG_IS_ENABLED(DM_SEQ_ALIAS) &&
                  (uc->uc_drv->flags & DM_UC_FLAG_SEQ_ALIAS)) {
                             /*
                             * Some devices, such as a SPI bus, I2C bus and serial ports
                             * are numbered using aliases.
                             */
                             if (CONFIG_IS_ENABLED(OF_CONTROL) &&
                                 !CONFIG_IS_ENABLED(OF_PLATDATA)) {
                                           if (uc->uc_drv->name && ofnode_valid(node)) {
                                                          if (!dev_read_alias_seq(dev, &dev->seq_)) {
                                                                        auto_seq = false;
                                                                        log_debug("   - seq=%d\n", dev->seq_);                      (1)
                                                                        }
                                           }
                             }
              }
              if (auto_seq && !(uc->uc_drv->flags & DM_UC_FLAG_NO_AUTO_SEQ))            (2)
                             dev->seq_ = uclass_find_next_free_seq(uc);
                ......
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
My questions are:

  1.  (1) and (2) are mutually exclusive, are they? What I mean is that only one of them can be executed for scanning and bonding one udevice.
  2.  What is the condition that (2) is executed?
Thanks!


BRs
Xiujun Wang