Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>]

On 3/1/2026 3:32 PM, Dmitry Baryshkov wrote:
> On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
>> From: Charan Teja Kalla <charan.kalla@xxxxxxxxxxxxxxxx>
>>
>> Change of_map_id() to take a pointer to struct of_phandle_args
>> instead of passing target device node and translated IDs separately.
>> Update all callers accordingly.
>>
>> Subsequent patch will make use of the args_count field in
>> struct of_phandle_args.
>>
>> Suggested-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
>> Signed-off-by: Charan Teja Kalla <charan.kalla@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>
>> ---
>>  drivers/iommu/of_iommu.c              |  2 +-
>>  drivers/of/base.c                     | 37 
>> +++++++++++++++++------------------
>>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>>  drivers/xen/grant-dma-ops.c           |  2 +-
>>  include/linux/of.h                    | 21 +++++++++++++-------
>>  6 files changed, 44 insertions(+), 30 deletions(-)
>>
> 
>> @@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
>>      }
>>  
>>      pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
>> -            id, target && *target ? *target : NULL);
>> +            id, arg->np ? arg->np : NULL);
> 
> Is it just 'args->np' then? If it's NULL, it's NULL anyway.
> 
Right, will update this.

>>  
>>      /* Bypasses translation */
>> -    if (id_out)
>> -            *id_out = id;
>> +    arg->args[0] = id;
>>      return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(of_map_id);
>> diff --git a/drivers/pci/controller/dwc/pci-imx6.c 
>> b/drivers/pci/controller/dwc/pci-imx6.c
>> index bff8289f804a..74fc603b3f84 100644
>> --- a/drivers/pci/controller/dwc/pci-imx6.c
>> +++ b/drivers/pci/controller/dwc/pci-imx6.c
>> @@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie 
>> *imx_pcie, u32 rid)
>>  {
>>      struct device *dev = imx_pcie->pci->dev;
>>      struct device_node *target;
>> +    struct of_phandle_args iommu_spec = { .args_count = 1 };
>>      u32 sid_i, sid_m;
>>      int err_i, err_m;
>>      u32 sid = 0;
>>  
>>      target = NULL;
>> -    err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
>> +    err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
>> +    if (!err_i) {
>> +            target = iommu_spec.np;
>> +            sid_i = iommu_spec.args[0];
>> +    }
>> +
>>      if (target) {
>>              of_node_put(target);
>>      } else {
>> diff --git a/drivers/pci/controller/pcie-apple.c 
>> b/drivers/pci/controller/pcie-apple.c
>> index a0937b7b3c4d..e1d4b37d200d 100644
>> --- a/drivers/pci/controller/pcie-apple.c
>> +++ b/drivers/pci/controller/pcie-apple.c
>> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct 
>> pci_host_bridge *bridge, struct pci_d
>>  {
>>      u32 sid, rid = pci_dev_id(pdev);
>>      struct apple_pcie_port *port;
>> +    struct of_phandle_args iommu_spec = { .args_count = 1 };
>>      int idx, err;
>>  
>>      port = apple_pcie_get_port(pdev);
>> @@ -764,10 +765,11 @@ static int apple_pcie_enable_device(struct 
>> pci_host_bridge *bridge, struct pci_d
>>      dev_dbg(&pdev->dev, "added to bus %s, index %d\n",
>>              pci_name(pdev->bus->self), port->idx);
>>  
>> -    err = of_map_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
>> +    err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
>>      if (err)
>>              return err;
> 
> of_node_put(iommu_spec.np);
> 

Sure, will add this.

>>  
>> +    sid = iommu_spec.args[0];
>>      mutex_lock(&port->pcie->lock);
>>  
>>      idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
>> diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
>> index 1b7696b2d762..5f1d6540049a 100644
>> --- a/drivers/xen/grant-dma-ops.c
>> +++ b/drivers/xen/grant-dma-ops.c
>> @@ -325,7 +325,7 @@ static int xen_dt_grant_init_backend_domid(struct device 
>> *dev,
>>              struct pci_dev *pdev = to_pci_dev(dev);
>>              u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
>>  
>> -            if (of_map_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
>> +            if (of_map_iommu_id(np, rid, &iommu_spec)) {
>>                      dev_dbg(dev, "Cannot translate ID\n");
>>                      return -ESRCH;
>>              }
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 824649867810..9d72d76f909d 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -463,7 +463,7 @@ bool of_console_check(const struct device_node *dn, char 
>> *name, int index);
>>  
>>  int of_map_id(const struct device_node *np, u32 id,
>>             const char *map_name, const char *map_mask_name,
>> -           struct device_node **target, u32 *id_out);
>> +           struct of_phandle_args *arg);
>>  
>>  phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
>>  
>> @@ -929,7 +929,7 @@ static inline void of_property_clear_flag(struct 
>> property *p, unsigned long flag
>>  
>>  static inline int of_map_id(const struct device_node *np, u32 id,
>>                           const char *map_name, const char *map_mask_name,
>> -                         struct device_node **target, u32 *id_out)
>> +                         struct of_phandle_args *arg)
>>  {
>>      return -EINVAL;
>>  }
>> @@ -1458,17 +1458,24 @@ static inline int of_property_read_s32(const struct 
>> device_node *np,
>>  }
>>  
>>  static inline int of_map_iommu_id(const struct device_node *np, u32 id,
>> -                              struct device_node **target, u32 *id_out)
>> +                              struct of_phandle_args *arg)
> 
> Document that it's the caller's responsibility to of_node_put() returned
> node. As it can be seen from the previous comment, it's not obvious.
> 

Sure, will add comment regarding this.

>>  {
>> -    return of_map_id(np, id, "iommu-map", "iommu-map-mask",
>> -                     target, id_out);
>> +    return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
>>  }
>>  
>>  static inline int of_map_msi_id(const struct device_node *np, u32 id,
>>                              struct device_node **target, u32 *id_out)
> 
> Is there a reason for chaning the of_map_iommu_id() args but not
> of_map_msi_id() args?
> 
 
Thanks for pointing this out. I’ll update the series to keep of_map_iommu_id()
and of_map_msi_id() aligned.

>>  {
>> -    return of_map_id(np, id, "msi-map", "msi-map-mask",
>> -                     target, id_out);
>> +    struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };
> 
> Which driver passes something being worth of storing in .np?
> 

You're right, There is no need to store these input args. Will remove these 
initializations.

Thanks,
Vijay

>> +    int ret;
>> +
>> +    ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
>> +    if (!ret) {
>> +            *target = msi_spec.np;
>> +            *id_out = msi_spec.args[0];
>> +    }
>> +
>> +    return ret;
>>  }
>>  
>>  #define of_for_each_phandle(it, err, np, ln, cn, cc)                        
>> \
>>
>> -- 
>> 2.34.1
>>
>