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

[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 <bibby.hsieh@xxxxxxxxxxxx>
> >>> Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
> >>> ---
> >>>  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, &spec);
> >>> +	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
> >>>
> > 
> >