Re: [PATCH v1 03/11] soc: mediatek: cmdq: add write_s function

[Matthias Brugger <matthias.bgg@gmail.com>]

On 22/06/2020 17:36, Dennis-YC Hsieh wrote:
> Hi Matthias,
> 
> thanks for your comment.
> 
> On Mon, 2020-06-22 at 13:07 +0200, Matthias Brugger wrote:
>>
>> On 21/06/2020 16:18, Dennis YC Hsieh wrote:
>>> add write_s function in cmdq helper functions which
>>> writes value contains in internal register to address
>>> with large dma access support.
>>>
>>> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@mediatek.com>
>>> ---
>>>  drivers/soc/mediatek/mtk-cmdq-helper.c   |   19 +++++++++++++++++++
>>>  include/linux/mailbox/mtk-cmdq-mailbox.h |    1 +
>>>  include/linux/soc/mediatek/mtk-cmdq.h    |   19 +++++++++++++++++++
>>>  3 files changed, 39 insertions(+)
>>>
>>> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> index bf32e3b2ca6c..817a5a97dbe5 100644
>>> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
>>> @@ -18,6 +18,10 @@ struct cmdq_instruction {
>>>  	union {
>>>  		u32 value;
>>>  		u32 mask;
>>> +		struct {
>>> +			u16 arg_c;
>>> +			u16 src_reg;
>>> +		};
>>>  	};
>>>  	union {
>>>  		u16 offset;
>>> @@ -222,6 +226,21 @@ int cmdq_pkt_write_mask(struct cmdq_pkt *pkt, u8 subsys,
>>>  }
>>>  EXPORT_SYMBOL(cmdq_pkt_write_mask);
>>>  
>>> +int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
>>> +		     u16 addr_low, u16 src_reg_idx)
>>> +{
>>
>> Do I understand correctly that we use CMDQ_ADDR_HIGH(addr) and
>> CMDQ_ADDR_LOW(addr) to calculate in the client high_addr_reg_idx and addr_low
>> respectively?
>>
>> In that case I think a better interface would be to pass the address and do the
>> high/low calculation in the cmdq_pkt_write_s
> 
> Not exactly. The high_addr_reg_idx parameter is index of internal
> register (which store address bit[47:16]), not result of
> CMDQ_ADDR_HIGH(addr). 
> 
> The CMDQ_ADDR_HIGH macro use in patch 02/11 cmdq_pkt_assign() api. This
> api helps assign address bit[47:16] into one of internal register by
> index. And same index could be use in cmdq_pkt_write_s(). The gce
> combine bit[47:16] in internal register and bit[15:0] in addr_low
> parameter to final address. So it is better to keep interface in this
> way.
> 

Got it, but then why don't we call cmdq_pkt_assign() in cmdq_pkt_write_s()? This
way we would get a clean API for what we want to do.
Do we expect other users of cmdq_pkt_assign()? Otherwise we could keep it
private the this file and don't export it.

By the way, why do you postfix the _s, I understand that it reflects the large
DMA access but I wonder why you choose '_s'.

Regards,
Matthias

> 
> Regards,
> Dennis
> 
>>
>> Regards,
>> Matthias
>>
>>> +	struct cmdq_instruction inst = {};
>>> +
>>> +	inst.op = CMDQ_CODE_WRITE_S;
>>> +	inst.src_t = CMDQ_REG_TYPE;
>>> +	inst.sop = high_addr_reg_idx;
>>> +	inst.offset = addr_low;
>>> +	inst.src_reg = src_reg_idx;
>>> +
>>> +	return cmdq_pkt_append_command(pkt, inst);
>>> +}
>>> +EXPORT_SYMBOL(cmdq_pkt_write_s);
>>> +
>>>  int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event)
>>>  {
>>>  	struct cmdq_instruction inst = { {0} };
>>> diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
>>> index 121c3bb6d3de..ee67dd3b86f5 100644
>>> --- a/include/linux/mailbox/mtk-cmdq-mailbox.h
>>> +++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
>>> @@ -59,6 +59,7 @@ enum cmdq_code {
>>>  	CMDQ_CODE_JUMP = 0x10,
>>>  	CMDQ_CODE_WFE = 0x20,
>>>  	CMDQ_CODE_EOC = 0x40,
>>> +	CMDQ_CODE_WRITE_S = 0x90,
>>>  	CMDQ_CODE_LOGIC = 0xa0,
>>>  };
>>>  
>>> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
>>> index 83340211e1d3..e1c5a7549b4f 100644
>>> --- a/include/linux/soc/mediatek/mtk-cmdq.h
>>> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
>>> @@ -12,6 +12,8 @@
>>>  #include <linux/timer.h>
>>>  
>>>  #define CMDQ_NO_TIMEOUT		0xffffffffu
>>> +#define CMDQ_ADDR_HIGH(addr)	((u32)(((addr) >> 16) & GENMASK(31, 0)))
>>> +#define CMDQ_ADDR_LOW(addr)	((u16)(addr) | BIT(1))
>>>  
>>>  struct cmdq_pkt;
>>>  
>>> @@ -103,6 +105,23 @@ int cmdq_pkt_write_mask(struct cmdq_pkt *pkt, u8 subsys,
>>>  			u16 offset, u32 value, u32 mask);
>>>  
>>>  /**
>>> + * cmdq_pkt_write_s() - append write_s command to the CMDQ packet
>>> + * @pkt:	the CMDQ packet
>>> + * @high_addr_reg_idx:	internal register ID which contains high address of pa
>>> + * @addr_low:	low address of pa
>>> + * @src_reg_idx:	the CMDQ internal register ID which cache source value
>>> + *
>>> + * Return: 0 for success; else the error code is returned
>>> + *
>>> + * Support write value to physical address without subsys. Use CMDQ_ADDR_HIGH()
>>> + * to get high address and call cmdq_pkt_assign() to assign value into internal
>>> + * reg. Also use CMDQ_ADDR_LOW() to get low address for addr_low parameter when
>>> + * call to this function.
>>> + */
>>> +int cmdq_pkt_write_s(struct cmdq_pkt *pkt, u16 high_addr_reg_idx,
>>> +		     u16 addr_low, u16 src_reg_idx);
>>> +
>>> +/**
>>>   * cmdq_pkt_wfe() - append wait for event command to the CMDQ packet
>>>   * @pkt:	the CMDQ packet
>>>   * @event:	the desired event type to "wait and CLEAR"
>>>
>