Subject: Re: [RESEND, PATCH v13 09/12] soc: mediatek: cmdq: define the instruction struct

From: Bibby Hsieh <[email-masked]>
Date: Tue, 27 Aug 2019 12:12:01 +0800

On Fri, 2019-08-23 at 15:50 +0200, Matthias Brugger wrote:
> 
> On 20/08/2019 10:49, Bibby Hsieh wrote:
> > Define an instruction structure for gce driver to append command.
> > This structure can make the client's code more readability.
> > 
> > Signed-off-by: Bibby Hsieh <[email-masked]>
> > Reviewed-by: CK Hu <[email-masked]>
> > ---
> >  drivers/soc/mediatek/mtk-cmdq-helper.c   | 106 +++++++++++++++--------
> >  include/linux/mailbox/mtk-cmdq-mailbox.h |   2 +
> >  2 files changed, 74 insertions(+), 34 deletions(-)
> > 
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index 7aa0517ff2f3..e3d5b0be8e79 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -9,12 +9,24 @@
> >  #include <linux/mailbox_controller.h>
> >  #include <linux/soc/mediatek/mtk-cmdq.h>
> >  
> > -#define CMDQ_ARG_A_WRITE_MASK	0xffff
> >  #define CMDQ_WRITE_ENABLE_MASK	BIT(0)
> >  #define CMDQ_EOC_IRQ_EN		BIT(0)
> >  #define CMDQ_EOC_CMD		((u64)((CMDQ_CODE_EOC << CMDQ_OP_CODE_SHIFT)) \
> >  				<< 32 | CMDQ_EOC_IRQ_EN)
> >  
> > +struct cmdq_instruction {
> > +	union {
> > +		u32 value;
> > +		u32 mask;
> > +	};
> > +	union {
> > +		u16 offset;
> > +		u16 event;
> > +	};
> > +	u8 subsys;
> > +	u8 op;
> > +};
> > +
> >  static void cmdq_client_timeout(struct timer_list *t)
> >  {
> >  	struct cmdq_client *client = from_timer(client, t, timer);
> > @@ -110,10 +122,8 @@ void cmdq_pkt_destroy(struct cmdq_pkt *pkt)
> >  }
> >  EXPORT_SYMBOL(cmdq_pkt_destroy);
> >  
> > -static int cmdq_pkt_append_command(struct cmdq_pkt *pkt, enum cmdq_code code,
> > -				   u32 arg_a, u32 arg_b)
> > +static struct cmdq_instruction *cmdq_pkt_append_command(struct cmdq_pkt *pkt)
> >  {
> > -	u64 *cmd_ptr;
> >  
> >  	if (unlikely(pkt->cmd_buf_size + CMDQ_INST_SIZE > pkt->buf_size)) {
> >  		/*
> > @@ -127,81 +137,109 @@ static int cmdq_pkt_append_command(struct cmdq_pkt *pkt, enum cmdq_code code,
> >  		pkt->cmd_buf_size += CMDQ_INST_SIZE;
> >  		WARN_ONCE(1, "%s: buffer size %u is too small !\n",
> >  			__func__, (u32)pkt->buf_size);
> > -		return -ENOMEM;
> > +		return NULL;
> >  	}
> > -	cmd_ptr = pkt->va_base + pkt->cmd_buf_size;
> > -	(*cmd_ptr) = (u64)((code << CMDQ_OP_CODE_SHIFT) | arg_a) << 32 | arg_b;
> > +
> > +	*(u64 *)(pkt->va_base + pkt->cmd_buf_size) = 0;>  	pkt->cmd_buf_size += CMDQ_INST_SIZE;
> >  
> > -	return 0;
> > +	return pkt->va_base + pkt->cmd_buf_size - CMDQ_INST_SIZE;
> >  }
> >  
> >  int cmdq_pkt_write(struct cmdq_pkt *pkt, u8 subsys, u16 offset, u32 value)
> >  {
> > -	u32 arg_a = (offset & CMDQ_ARG_A_WRITE_MASK) |
> > -		    (subsys << CMDQ_SUBSYS_SHIFT);
> > +	struct cmdq_instruction *inst;
> > +
> > +	inst = cmdq_pkt_append_command(pkt);
> > +	if (!inst)
> > +		return -ENOMEM;
> > +
> > +	inst->op = CMDQ_CODE_WRITE;
> > +	inst->value = value;
> > +	inst->offset = offset;
> > +	inst->subsys = subsys;
> >  
> 
> I can see that using cmdq_instruction will make the code more readable, but I
> dislike the approach that cmdq_pkt_append_command returns a pointer where we
> write the instruction to. Better we pass inst to cmdq_pkt_append_command() and
> write it there to cmd_ptr.
> 
> I think this way we can get rid of explicitly setting the memory to zero:
> *(u64 *)(pkt->va_base + pkt->cmd_buf_size) = 0;
> 
> And if we pass the inst to the append_command we don't have to change the return
> value handling of cmdq_pkt_append_command(), which makes the patch easier to
> understand.

Ok, I will change and resend it.

> 
> > -	return cmdq_pkt_append_command(pkt, CMDQ_CODE_WRITE, arg_a, value);
> > +	return 0;
> >  }
> >  EXPORT_SYMBOL(cmdq_pkt_write);
> >  
> >  int cmdq_pkt_write_mask(struct cmdq_pkt *pkt, u8 subsys,
> >  			u16 offset, u32 value, u32 mask)
> >  {
> > -	u32 offset_mask = offset;
> > -	int err = 0;
> > +	struct cmdq_instruction *inst;
> > +	u16 offset_mask = offset;
> >  
> >  	if (mask != 0xffffffff) {
> > -		err = cmdq_pkt_append_command(pkt, CMDQ_CODE_MASK, 0, ~mask);
> > +		inst = cmdq_pkt_append_command(pkt);
> > +		if (!inst)
> > +			return -ENOMEM;
> > +
> > +		inst->op = CMDQ_CODE_MASK;
> > +		inst->mask = ~mask;
> >  		offset_mask |= CMDQ_WRITE_ENABLE_MASK;
> >  	}
> > -	err |= cmdq_pkt_write(pkt, value, subsys, offset_mask);
> >  
> > -	return err;
> > +	return cmdq_pkt_write(pkt, subsys, offset_mask, value);
> >  }
> >  EXPORT_SYMBOL(cmdq_pkt_write_mask);
> >  
> >  int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event)
> >  {
> > -	u32 arg_b;
> > +	struct cmdq_instruction *inst;
> >  
> >  	if (event >= CMDQ_MAX_EVENT)
> >  		return -EINVAL;
> >  
> > -	/*
> > -	 * WFE arg_b
> > -	 * bit 0-11: wait value
> > -	 * bit 15: 1 - wait, 0 - no wait
> > -	 * bit 16-27: update value
> > -	 * bit 31: 1 - update, 0 - no update
> > -	 */
> 
> I have no strong opinion of CMDQ_WFE_OPTION but if you want to introduce it,
> then please copy the comment over to include/linux/mailbox/mtk-cmdq-mailbox.h

Ok. let's move the descriptions to header.
> 
> Just one question, why did you call it _OPTION? It's not really expressive for me.

Actually, _OPTION is come from our hardware design name...

> 
> > -	arg_b = CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> > +	inst = cmdq_pkt_append_command(pkt);
> > +	if (!inst)
> > +		return -ENOMEM;
> > +
> > +	inst->op = CMDQ_CODE_WFE;
> > +	inst->value = CMDQ_WFE_OPTION;
> > +	inst->event = event;
> >  
> > -	return cmdq_pkt_append_command(pkt, CMDQ_CODE_WFE, event, arg_b);
> > +	return 0;
> >  }
> >  EXPORT_SYMBOL(cmdq_pkt_wfe);
> >  
> >  int cmdq_pkt_clear_event(struct cmdq_pkt *pkt, u16 event)
> >  {
> > +	struct cmdq_instruction *inst;
> > +
> >  	if (event >= CMDQ_MAX_EVENT)
> >  		return -EINVAL;
> >  
> > -	return cmdq_pkt_append_command(pkt, CMDQ_CODE_WFE, event,
> > -				       CMDQ_WFE_UPDATE);
> > +	inst = cmdq_pkt_append_command(pkt);
> > +	if (!inst)
> > +		return -ENOMEM;
> > +
> > +	inst->op = CMDQ_CODE_WFE;
> > +	inst->value = CMDQ_WFE_UPDATE;
> > +	inst->event = event;
> > +
> > +	return 0;
> >  }
> >  EXPORT_SYMBOL(cmdq_pkt_clear_event);
> >  
> >  static int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
> >  {
> > -	int err;
> > +	struct cmdq_instruction *inst;
> > +
> > +	inst = cmdq_pkt_append_command(pkt);
> > +	if (!inst)
> > +		return -ENOMEM;
> >  
> > -	/* insert EOC and generate IRQ for each command iteration */
> 
> Please don't delete the comment.
> 
> > -	err = cmdq_pkt_append_command(pkt, CMDQ_CODE_EOC, 0, CMDQ_EOC_IRQ_EN);
> > +	inst->op = CMDQ_CODE_EOC;
> > +	inst->value = CMDQ_EOC_IRQ_EN;
> >  
> > -	/* JUMP to end */
> 
> Same here.
> 
> Regards,
> Matthias
> 
> > -	err |= cmdq_pkt_append_command(pkt, CMDQ_CODE_JUMP, 0, CMDQ_JUMP_PASS);
> > +	inst = cmdq_pkt_append_command(pkt);
> > +	if (!inst)
> > +		return -ENOMEM;
> > +
> > +	inst->op = CMDQ_CODE_JUMP;
> > +	inst->value = CMDQ_JUMP_PASS;
> >  
> > -	return err;
> > +	return 0;
> >  }
> >  
> >  static void cmdq_pkt_flush_async_cb(struct cmdq_cb_data data)
> > diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
> > index 911475da7a53..c8adedefaf42 100644
> > --- a/include/linux/mailbox/mtk-cmdq-mailbox.h
> > +++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
> > @@ -19,6 +19,8 @@
> >  #define CMDQ_WFE_UPDATE			BIT(31)
> >  #define CMDQ_WFE_WAIT			BIT(15)
> >  #define CMDQ_WFE_WAIT_VALUE		0x1
> > +#define CMDQ_WFE_OPTION			(CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | \
> > +					CMDQ_WFE_WAIT_VALUE)
> >  /** cmdq event maximum */
> >  #define CMDQ_MAX_EVENT			0x3ff
> >  
> > 

-- 
Bibby

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