Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-28 Thread Bibby Hsieh
On Tue, 2019-08-27 at 12:13 +0200, Matthias Brugger wrote:
> 
> On 27/08/2019 05:59, Bibby Hsieh wrote:
> > On Fri, 2019-08-23 at 16:21 +0200, Matthias Brugger wrote:
> >>
> >> On 20/08/2019 10:49, Bibby Hsieh wrote:
> >>> GCE cannot know the register base address, this function
> >>> can help cmdq client to get the cmdq_client_reg structure.
> >>>
> >>> Signed-off-by: Bibby Hsieh 
> >>> Reviewed-by: CK Hu 
> >>> ---
> >>>  drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
> >>>  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
> >>>  2 files changed, 50 insertions(+)
> >>>
> >>> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
> >>> b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> index c53f8476c68d..80f75a1075b4 100644
> >>> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> >>> @@ -27,6 +27,35 @@ struct cmdq_instruction {
> >>>   u8 op;
> >>>  };
> >>>  
> >>> +int cmdq_dev_get_client_reg(struct device *dev,
> >>> + struct cmdq_client_reg *client_reg, int idx)
> >>> +{
> >>
> >> Can't we do/call this in cmdq_mbox_create parsing the number of 
> >> gce-client-reg
> >> properties we have and allocating these using a pointer to cmdq_client_reg 
> >> in
> >> cmdq_client?
> >> We will have to free the pointer then in cmdq_mbox_destroy.
> >>
> >> Regards,
> >> Matthias
> > 
> > I don't think we need to keep the cmdq_client_reg in cmdq_client
> > structure.
> > Because our client will have own data structure, they will copy the
> > client_reg information into their own structure.
> > 
> > In the design now, we do not allocate the cmdq_client_reg, client pass
> > the cmdq_client_reg pointer into this API.
> > Client will destroy the pointer after they get the information they
> > want.
> > 
> 
> My point wasn't so much about the lifecycle of the object, but the fact that 
> we
> add another call, which can be already full-filled by a necessary previous 
> call
> to cmdq_mbox_create. So I would prefer to add the information gathering for
> cmdq_client_reg in this call, and let it live there for the time cmdq_client
> lives. In the end we are talking about 40 bits of memory.
> 

Thanks for the comments. :D

Actually, I'm working for developing the chandes for MTK DRM apply cmdq
interface.
For MTK DRM, all the components included in MTK_CRTC use one mailbox
channel. According to [1], we create mailbox channel by mmsys device
node after get all the informations (include cmdq_client_reg) about
every device node of display components respectively. Please refer to
[2], [3] and [4], I'm going to upstream them recently.

If create mailbox channel and get the cmdq_client_reg in the same device
node, your suggestion is good for me.
But from display and mdp's viewpoint now, I don't think it is convenient
for them.

So I still prefer separate this function out of cmdq_mbox_create.:D


[1]
https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/mediatek/mt8173.dtsi#907
[2] get cmdq_client_reg in mtk_ddp_comp_init()
https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1746354/12/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c#431
[3] create mailbox channel in mtk_drm_crtc_create()
https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1746354/12/drivers/gpu/drm/mediatek/mtk_drm_crtc.c#814
[4] After component_bind_all(), the mtk_drm_crtc_create will be called 
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/e15c2dc6ceb4810a2090cd11a512932095866559/drivers/gpu/drm/mediatek/mtk_drm_drv.c#452

Thanks.
Bibby

> Regards,
> Matthias
> 
> > Thanks for the comments so much.
> > 
> > Bibby
> > 
> >>
> >>> + struct of_phandle_args spec;
> >>> + int err;
> >>> +
> >>> + if (!client_reg)
> >>> + return -ENOENT;
> >>> +
> >>> + err = of_parse_phandle_with_fixed_args(dev->of_node,
> >>> +"mediatek,gce-client-reg",
> >>> +3, idx, );
> >>> + if (err < 0) {
> >>> + dev_err(dev,
> >>> + "error %d can't parse gce-client-reg property (%d)",
> >>> + err, idx);
> >>> +
> >>> + return err;
> >>> + }
> >>> +
> >>> + client_reg->subsys = (u8)spec.args[0];
> >>> + client_reg->offset = (u16)spec.args[1];
> >>> + client_reg->size = (u16)spec.args[2];
> >>> + of_node_put(spec.np);
> >>> +
> >>> + return 0;
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
> >>> +
> >>>  static void cmdq_client_timeout(struct timer_list *t)
> >>>  {
> >>>   struct cmdq_client *client = from_timer(client, t, timer);
> >>> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
> >>> b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> index a345870a6d10..02ddd60b212f 100644
> >>> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> >>> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> >>> @@ -15,6 +15,12 @@
> >>>  
> >>>  struct cmdq_pkt;
> >>>  
> >>> +struct cmdq_client_reg {
> >>> + 

Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-27 Thread Matthias Brugger



On 27/08/2019 05:59, Bibby Hsieh wrote:
> On Fri, 2019-08-23 at 16:21 +0200, Matthias Brugger wrote:
>>
>> On 20/08/2019 10:49, Bibby Hsieh wrote:
>>> GCE cannot know the register base address, this function
>>> can help cmdq client to get the cmdq_client_reg structure.
>>>
>>> Signed-off-by: Bibby Hsieh 
>>> Reviewed-by: CK Hu 
>>> ---
>>>  drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
>>>  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
>>>  2 files changed, 50 insertions(+)
>>>
>>> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
>>> b/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> index c53f8476c68d..80f75a1075b4 100644
>>> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> @@ -27,6 +27,35 @@ struct cmdq_instruction {
>>> u8 op;
>>>  };
>>>  
>>> +int cmdq_dev_get_client_reg(struct device *dev,
>>> +   struct cmdq_client_reg *client_reg, int idx)
>>> +{
>>
>> Can't we do/call this in cmdq_mbox_create parsing the number of 
>> gce-client-reg
>> properties we have and allocating these using a pointer to cmdq_client_reg in
>> cmdq_client?
>> We will have to free the pointer then in cmdq_mbox_destroy.
>>
>> Regards,
>> Matthias
> 
> I don't think we need to keep the cmdq_client_reg in cmdq_client
> structure.
> Because our client will have own data structure, they will copy the
> client_reg information into their own structure.
> 
> In the design now, we do not allocate the cmdq_client_reg, client pass
> the cmdq_client_reg pointer into this API.
> Client will destroy the pointer after they get the information they
> want.
> 

My point wasn't so much about the lifecycle of the object, but the fact that we
add another call, which can be already full-filled by a necessary previous call
to cmdq_mbox_create. So I would prefer to add the information gathering for
cmdq_client_reg in this call, and let it live there for the time cmdq_client
lives. In the end we are talking about 40 bits of memory.

Regards,
Matthias

> Thanks for the comments so much.
> 
> Bibby
> 
>>
>>> +   struct of_phandle_args spec;
>>> +   int err;
>>> +
>>> +   if (!client_reg)
>>> +   return -ENOENT;
>>> +
>>> +   err = of_parse_phandle_with_fixed_args(dev->of_node,
>>> +  "mediatek,gce-client-reg",
>>> +  3, idx, );
>>> +   if (err < 0) {
>>> +   dev_err(dev,
>>> +   "error %d can't parse gce-client-reg property (%d)",
>>> +   err, idx);
>>> +
>>> +   return err;
>>> +   }
>>> +
>>> +   client_reg->subsys = (u8)spec.args[0];
>>> +   client_reg->offset = (u16)spec.args[1];
>>> +   client_reg->size = (u16)spec.args[2];
>>> +   of_node_put(spec.np);
>>> +
>>> +   return 0;
>>> +}
>>> +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
>>> +
>>>  static void cmdq_client_timeout(struct timer_list *t)
>>>  {
>>> struct cmdq_client *client = from_timer(client, t, timer);
>>> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
>>> b/include/linux/soc/mediatek/mtk-cmdq.h
>>> index a345870a6d10..02ddd60b212f 100644
>>> --- a/include/linux/soc/mediatek/mtk-cmdq.h
>>> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
>>> @@ -15,6 +15,12 @@
>>>  
>>>  struct cmdq_pkt;
>>>  
>>> +struct cmdq_client_reg {
>>> +   u8 subsys;
>>> +   u16 offset;
>>> +   u16 size;
>>> +};
>>> +
>>>  struct cmdq_client {
>>> spinlock_t lock;
>>> u32 pkt_cnt;
>>> @@ -24,6 +30,21 @@ struct cmdq_client {
>>> u32 timeout_ms; /* in unit of microsecond */
>>>  };
>>>  
>>> +/**
>>> + * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
>>> + *node of CMDQ client
>>> + * @dev:   device of CMDQ mailbox client
>>> + * @client_reg: CMDQ client reg pointer
>>> + * @idx:   the index of desired reg
>>> + *
>>> + * Return: 0 for success; else the error code is returned
>>> + *
>>> + * Help CMDQ client parsing the cmdq client reg
>>> + * from the device node of CMDQ client.
>>> + */
>>> +int cmdq_dev_get_client_reg(struct device *dev,
>>> +   struct cmdq_client_reg *client_reg, int idx);
>>> +
>>>  /**
>>>   * cmdq_mbox_create() - create CMDQ mailbox client and channel
>>>   * @dev:   device of CMDQ mailbox client
>>>
> 
> 


Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-26 Thread Bibby Hsieh
On Fri, 2019-08-23 at 16:21 +0200, Matthias Brugger wrote:
> 
> On 20/08/2019 10:49, Bibby Hsieh wrote:
> > GCE cannot know the register base address, this function
> > can help cmdq client to get the cmdq_client_reg structure.
> > 
> > Signed-off-by: Bibby Hsieh 
> > Reviewed-by: CK Hu 
> > ---
> >  drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
> >  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
> >  2 files changed, 50 insertions(+)
> > 
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
> > b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index c53f8476c68d..80f75a1075b4 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -27,6 +27,35 @@ struct cmdq_instruction {
> > u8 op;
> >  };
> >  
> > +int cmdq_dev_get_client_reg(struct device *dev,
> > +   struct cmdq_client_reg *client_reg, int idx)
> > +{
> 
> Can't we do/call this in cmdq_mbox_create parsing the number of gce-client-reg
> properties we have and allocating these using a pointer to cmdq_client_reg in
> cmdq_client?
> We will have to free the pointer then in cmdq_mbox_destroy.
> 
> Regards,
> Matthias

I don't think we need to keep the cmdq_client_reg in cmdq_client
structure.
Because our client will have own data structure, they will copy the
client_reg information into their own structure.

In the design now, we do not allocate the cmdq_client_reg, client pass
the cmdq_client_reg pointer into this API.
Client will destroy the pointer after they get the information they
want.

Thanks for the comments so much.

Bibby

> 
> > +   struct of_phandle_args spec;
> > +   int err;
> > +
> > +   if (!client_reg)
> > +   return -ENOENT;
> > +
> > +   err = of_parse_phandle_with_fixed_args(dev->of_node,
> > +  "mediatek,gce-client-reg",
> > +  3, idx, );
> > +   if (err < 0) {
> > +   dev_err(dev,
> > +   "error %d can't parse gce-client-reg property (%d)",
> > +   err, idx);
> > +
> > +   return err;
> > +   }
> > +
> > +   client_reg->subsys = (u8)spec.args[0];
> > +   client_reg->offset = (u16)spec.args[1];
> > +   client_reg->size = (u16)spec.args[2];
> > +   of_node_put(spec.np);
> > +
> > +   return 0;
> > +}
> > +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
> > +
> >  static void cmdq_client_timeout(struct timer_list *t)
> >  {
> > struct cmdq_client *client = from_timer(client, t, timer);
> > diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
> > b/include/linux/soc/mediatek/mtk-cmdq.h
> > index a345870a6d10..02ddd60b212f 100644
> > --- a/include/linux/soc/mediatek/mtk-cmdq.h
> > +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> > @@ -15,6 +15,12 @@
> >  
> >  struct cmdq_pkt;
> >  
> > +struct cmdq_client_reg {
> > +   u8 subsys;
> > +   u16 offset;
> > +   u16 size;
> > +};
> > +
> >  struct cmdq_client {
> > spinlock_t lock;
> > u32 pkt_cnt;
> > @@ -24,6 +30,21 @@ struct cmdq_client {
> > u32 timeout_ms; /* in unit of microsecond */
> >  };
> >  
> > +/**
> > + * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
> > + *node of CMDQ client
> > + * @dev:   device of CMDQ mailbox client
> > + * @client_reg: CMDQ client reg pointer
> > + * @idx:   the index of desired reg
> > + *
> > + * Return: 0 for success; else the error code is returned
> > + *
> > + * Help CMDQ client parsing the cmdq client reg
> > + * from the device node of CMDQ client.
> > + */
> > +int cmdq_dev_get_client_reg(struct device *dev,
> > +   struct cmdq_client_reg *client_reg, int idx);
> > +
> >  /**
> >   * cmdq_mbox_create() - create CMDQ mailbox client and channel
> >   * @dev:   device of CMDQ mailbox client
> > 




Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-23 Thread Matthias Brugger



On 20/08/2019 10:49, Bibby Hsieh wrote:
> GCE cannot know the register base address, this function
> can help cmdq client to get the cmdq_client_reg structure.
> 
> Signed-off-by: Bibby Hsieh 
> Reviewed-by: CK Hu 
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
>  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
> b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index c53f8476c68d..80f75a1075b4 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -27,6 +27,35 @@ struct cmdq_instruction {
>   u8 op;
>  };
>  
> +int cmdq_dev_get_client_reg(struct device *dev,
> + struct cmdq_client_reg *client_reg, int idx)
> +{

Can't we do/call this in cmdq_mbox_create parsing the number of gce-client-reg
properties we have and allocating these using a pointer to cmdq_client_reg in
cmdq_client?
We will have to free the pointer then in cmdq_mbox_destroy.

Regards,
Matthias

> + struct of_phandle_args spec;
> + int err;
> +
> + if (!client_reg)
> + return -ENOENT;
> +
> + err = of_parse_phandle_with_fixed_args(dev->of_node,
> +"mediatek,gce-client-reg",
> +3, idx, );
> + if (err < 0) {
> + dev_err(dev,
> + "error %d can't parse gce-client-reg property (%d)",
> + err, idx);
> +
> + return err;
> + }
> +
> + client_reg->subsys = (u8)spec.args[0];
> + client_reg->offset = (u16)spec.args[1];
> + client_reg->size = (u16)spec.args[2];
> + of_node_put(spec.np);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
> +
>  static void cmdq_client_timeout(struct timer_list *t)
>  {
>   struct cmdq_client *client = from_timer(client, t, timer);
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
> b/include/linux/soc/mediatek/mtk-cmdq.h
> index a345870a6d10..02ddd60b212f 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -15,6 +15,12 @@
>  
>  struct cmdq_pkt;
>  
> +struct cmdq_client_reg {
> + u8 subsys;
> + u16 offset;
> + u16 size;
> +};
> +
>  struct cmdq_client {
>   spinlock_t lock;
>   u32 pkt_cnt;
> @@ -24,6 +30,21 @@ struct cmdq_client {
>   u32 timeout_ms; /* in unit of microsecond */
>  };
>  
> +/**
> + * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
> + *  node of CMDQ client
> + * @dev: device of CMDQ mailbox client
> + * @client_reg: CMDQ client reg pointer
> + * @idx: the index of desired reg
> + *
> + * Return: 0 for success; else the error code is returned
> + *
> + * Help CMDQ client parsing the cmdq client reg
> + * from the device node of CMDQ client.
> + */
> +int cmdq_dev_get_client_reg(struct device *dev,
> + struct cmdq_client_reg *client_reg, int idx);
> +
>  /**
>   * cmdq_mbox_create() - create CMDQ mailbox client and channel
>   * @dev: device of CMDQ mailbox client
> 


Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-20 Thread houlong wei
On Tue, 2019-08-20 at 16:49 +0800, Bibby Hsieh wrote:
> GCE cannot know the register base address, this function
> can help cmdq client to get the cmdq_client_reg structure.
> 
> Signed-off-by: Bibby Hsieh 
> Reviewed-by: CK Hu 
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
>  include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
> b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index c53f8476c68d..80f75a1075b4 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -27,6 +27,35 @@ struct cmdq_instruction {
>   u8 op;
>  };
>  
> +int cmdq_dev_get_client_reg(struct device *dev,
> + struct cmdq_client_reg *client_reg, int idx)
> +{
> + struct of_phandle_args spec;
> + int err;
> +
> + if (!client_reg)
> + return -ENOENT;
> +
> + err = of_parse_phandle_with_fixed_args(dev->of_node,
> +"mediatek,gce-client-reg",
> +3, idx, );
> + if (err < 0) {
> + dev_err(dev,
> + "error %d can't parse gce-client-reg property (%d)",
> + err, idx);
> +
> + return err;
> + }
> +
> + client_reg->subsys = (u8)spec.args[0];
> + client_reg->offset = (u16)spec.args[1];
> + client_reg->size = (u16)spec.args[2];
> + of_node_put(spec.np);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(cmdq_dev_get_client_reg);
> +
>  static void cmdq_client_timeout(struct timer_list *t)
>  {
>   struct cmdq_client *client = from_timer(client, t, timer);
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
> b/include/linux/soc/mediatek/mtk-cmdq.h
> index a345870a6d10..02ddd60b212f 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -15,6 +15,12 @@
>  
>  struct cmdq_pkt;
>  
> +struct cmdq_client_reg {
> + u8 subsys;
> + u16 offset;
> + u16 size;
> +};
> +
>  struct cmdq_client {
>   spinlock_t lock;
>   u32 pkt_cnt;
> @@ -24,6 +30,21 @@ struct cmdq_client {
>   u32 timeout_ms; /* in unit of microsecond */
>  };
>  
> +/**
> + * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
> + *  node of CMDQ client
> + * @dev: device of CMDQ mailbox client
> + * @client_reg: CMDQ client reg pointer
> + * @idx: the index of desired reg
> + *
> + * Return: 0 for success; else the error code is returned
> + *
> + * Help CMDQ client parsing the cmdq client reg
> + * from the device node of CMDQ client.
> + */
> +int cmdq_dev_get_client_reg(struct device *dev,
> + struct cmdq_client_reg *client_reg, int idx);
> +
>  /**
>   * cmdq_mbox_create() - create CMDQ mailbox client and channel
>   * @dev: device of CMDQ mailbox client

Reviewed-by: Houlong Wei 



Re: [RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-20 Thread houlong wei
Reviewed-by: Houlong Wei 





[RESEND, PATCH v13 11/12] soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

2019-08-20 Thread Bibby Hsieh
GCE cannot know the register base address, this function
can help cmdq client to get the cmdq_client_reg structure.

Signed-off-by: Bibby Hsieh 
Reviewed-by: CK Hu 
---
 drivers/soc/mediatek/mtk-cmdq-helper.c | 29 ++
 include/linux/soc/mediatek/mtk-cmdq.h  | 21 +++
 2 files changed, 50 insertions(+)

diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c 
b/drivers/soc/mediatek/mtk-cmdq-helper.c
index c53f8476c68d..80f75a1075b4 100644
--- a/drivers/soc/mediatek/mtk-cmdq-helper.c
+++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
@@ -27,6 +27,35 @@ struct cmdq_instruction {
u8 op;
 };
 
+int cmdq_dev_get_client_reg(struct device *dev,
+   struct cmdq_client_reg *client_reg, int idx)
+{
+   struct of_phandle_args spec;
+   int err;
+
+   if (!client_reg)
+   return -ENOENT;
+
+   err = of_parse_phandle_with_fixed_args(dev->of_node,
+  "mediatek,gce-client-reg",
+  3, idx, );
+   if (err < 0) {
+   dev_err(dev,
+   "error %d can't parse gce-client-reg property (%d)",
+   err, idx);
+
+   return err;
+   }
+
+   client_reg->subsys = (u8)spec.args[0];
+   client_reg->offset = (u16)spec.args[1];
+   client_reg->size = (u16)spec.args[2];
+   of_node_put(spec.np);
+
+   return 0;
+}
+EXPORT_SYMBOL(cmdq_dev_get_client_reg);
+
 static void cmdq_client_timeout(struct timer_list *t)
 {
struct cmdq_client *client = from_timer(client, t, timer);
diff --git a/include/linux/soc/mediatek/mtk-cmdq.h 
b/include/linux/soc/mediatek/mtk-cmdq.h
index a345870a6d10..02ddd60b212f 100644
--- a/include/linux/soc/mediatek/mtk-cmdq.h
+++ b/include/linux/soc/mediatek/mtk-cmdq.h
@@ -15,6 +15,12 @@
 
 struct cmdq_pkt;
 
+struct cmdq_client_reg {
+   u8 subsys;
+   u16 offset;
+   u16 size;
+};
+
 struct cmdq_client {
spinlock_t lock;
u32 pkt_cnt;
@@ -24,6 +30,21 @@ struct cmdq_client {
u32 timeout_ms; /* in unit of microsecond */
 };
 
+/**
+ * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
+ *node of CMDQ client
+ * @dev:   device of CMDQ mailbox client
+ * @client_reg: CMDQ client reg pointer
+ * @idx:   the index of desired reg
+ *
+ * Return: 0 for success; else the error code is returned
+ *
+ * Help CMDQ client parsing the cmdq client reg
+ * from the device node of CMDQ client.
+ */
+int cmdq_dev_get_client_reg(struct device *dev,
+   struct cmdq_client_reg *client_reg, int idx);
+
 /**
  * cmdq_mbox_create() - create CMDQ mailbox client and channel
  * @dev:   device of CMDQ mailbox client
-- 
2.18.0