Date:   Fri, 15 Feb 2019 00:12:12 +0800
From:   Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>
To:     CK Hu <ck.hu@...iatek.com>
CC:     Jassi Brar <jassisinghbrar@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        Houlong Wei (魏厚龙) 
        <houlong.wei@...iatek.com>, Bibby Hsieh <bibby.hsieh@...iatek.com>
Subject: Re: [PATCH 3/3] mailbox: mediatek: Remove busylist

Hi CK,

On Fri, 2019-02-15 at 00:01 +0800, CK Hu wrote:
> Hi, Dennis:
> 
> On Tue, 2019-02-12 at 10:18 +0800, Dennis-YC Hsieh wrote:
> > Hi CK,
> > 
> > On Tue, 2019-01-29 at 17:20 +0800, Houlong Wei (魏厚龙) wrote:
> > > -----Original Message-----
> > > From: CK Hu [mailto:ck.hu@...iatek.com] 
> > > Sent: Wednesday, January 16, 2019 1:05 PM
> > > To: Jassi Brar <jassisinghbrar@...il.com>; Matthias Brugger <matthias.bgg@...il.com>; Houlong Wei (魏厚龙) <houlong.wei@...iatek.com>
> > > Cc: linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-mediatek@...ts.infradead.org; srv_heupstream <srv_heupstream@...iatek.com>; CK Hu (胡俊光) <ck.hu@...iatek.com>
> > > Subject: [PATCH 3/3] mailbox: mediatek: Remove busylist
> > > 
> > > After implement abort_data, controller need not to implement its own queue. Remove busylist because it's useless.
> > 
> > Remove busy list in controller makes client driver have no way to queue
> > pkt in gce hardware thread, which may hurt display and multimedia
> > performance since each pkt waits IRQ delay before previous pkt. Suggest
> > keep busy list design.
> 
> If some client driver need gce to cascade pkt to prevent irq delay, I
> should keep busylist. For drm driver, I still want to apply the first
> two patches of this series and remove atomic feature because drm could
> keep just one pkt and reuse it to prevent frequently allocate/free pkt
> and the total commands executed in vblank period would be
> well-controlled. Do you have any concern about removing atomic feature?
> 
> Regards,
> CK
> 

I have no concern on remove atomic feature.


Regards,
Dennis


> > 
> > 
> > Regards,
> > Dennis
> > 
> > > 
> > > Signed-off-by: CK Hu <ck.hu@...iatek.com>
> > > ---
> > >  drivers/mailbox/mtk-cmdq-mailbox.c | 255 ++++-------------------------
> > >  1 file changed, 29 insertions(+), 226 deletions(-)
> > > 
> > > diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
> > > index f2219f263ef6..45c59f677ecb 100644
> > > --- a/drivers/mailbox/mtk-cmdq-mailbox.c
> > > +++ b/drivers/mailbox/mtk-cmdq-mailbox.c
> > > @@ -16,9 +16,7 @@
> > >  #include <linux/mailbox/mtk-cmdq-mailbox.h>
> > >  #include <linux/of_device.h>
> > >  
> > > -#define CMDQ_OP_CODE_MASK		(0xff << CMDQ_OP_CODE_SHIFT)
> > >  #define CMDQ_IRQ_MASK			0xffff
> > > -#define CMDQ_NUM_CMD(t)			(t->cmd_buf_size / CMDQ_INST_SIZE)
> > >  
> > >  #define CMDQ_CURR_IRQ_STATUS		0x10
> > >  #define CMDQ_THR_SLOT_CYCLES		0x30
> > > @@ -47,22 +45,10 @@
> > >  #define CMDQ_THR_IRQ_EN			(CMDQ_THR_IRQ_ERROR | CMDQ_THR_IRQ_DONE)
> > >  #define CMDQ_THR_IS_WAITING		BIT(31)
> > >  
> > > -#define CMDQ_JUMP_BY_OFFSET		0x10000000
> > > -#define CMDQ_JUMP_BY_PA			0x10000001
> > > -
> > >  struct cmdq_thread {
> > >  	struct mbox_chan	*chan;
> > >  	void __iomem		*base;
> > > -	struct list_head	task_busy_list;
> > >  	u32			priority;
> > > -	bool			atomic_exec;
> > > -};
> > > -
> > > -struct cmdq_task {
> > > -	struct cmdq		*cmdq;
> > > -	struct list_head	list_entry;
> > > -	dma_addr_t		pa_base;
> > > -	struct cmdq_thread	*thread;
> > >  	struct cmdq_pkt		*pkt; /* the packet sent from mailbox client */
> > >  };
> > >  
> > > @@ -130,171 +116,47 @@ static void cmdq_thread_disable(struct cmdq *cmdq, struct cmdq_thread *thread)
> > >  	writel(CMDQ_THR_DISABLED, thread->base + CMDQ_THR_ENABLE_TASK);  }
> > >  
> > > -/* notify GCE to re-fetch commands by setting GCE thread PC */ -static void cmdq_thread_invalidate_fetched_data(struct cmdq_thread *thread) -{
> > > -	writel(readl(thread->base + CMDQ_THR_CURR_ADDR),
> > > -	       thread->base + CMDQ_THR_CURR_ADDR);
> > > -}
> > > -
> > > -static void cmdq_task_insert_into_thread(struct cmdq_task *task) -{
> > > -	struct device *dev = task->cmdq->mbox.dev;
> > > -	struct cmdq_thread *thread = task->thread;
> > > -	struct cmdq_task *prev_task = list_last_entry(
> > > -			&thread->task_busy_list, typeof(*task), list_entry);
> > > -	u64 *prev_task_base = prev_task->pkt->va_base;
> > > -
> > > -	/* let previous task jump to this task */
> > > -	dma_sync_single_for_cpu(dev, prev_task->pa_base,
> > > -				prev_task->pkt->cmd_buf_size, DMA_TO_DEVICE);
> > > -	prev_task_base[CMDQ_NUM_CMD(prev_task->pkt) - 1] =
> > > -		(u64)CMDQ_JUMP_BY_PA << 32 | task->pa_base;
> > > -	dma_sync_single_for_device(dev, prev_task->pa_base,
> > > -				   prev_task->pkt->cmd_buf_size, DMA_TO_DEVICE);
> > > -
> > > -	cmdq_thread_invalidate_fetched_data(thread);
> > > -}
> > > -
> > > -static bool cmdq_command_is_wfe(u64 cmd) -{
> > > -	u64 wfe_option = CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> > > -	u64 wfe_op = (u64)(CMDQ_CODE_WFE << CMDQ_OP_CODE_SHIFT) << 32;
> > > -	u64 wfe_mask = (u64)CMDQ_OP_CODE_MASK << 32 | 0xffffffff;
> > > -
> > > -	return ((cmd & wfe_mask) == (wfe_op | wfe_option));
> > > -}
> > > -
> > > -/* we assume tasks in the same display GCE thread are waiting the same event. */ -static void cmdq_task_remove_wfe(struct cmdq_task *task) -{
> > > -	struct device *dev = task->cmdq->mbox.dev;
> > > -	u64 *base = task->pkt->va_base;
> > > -	int i;
> > > -
> > > -	dma_sync_single_for_cpu(dev, task->pa_base, task->pkt->cmd_buf_size,
> > > -				DMA_TO_DEVICE);
> > > -	for (i = 0; i < CMDQ_NUM_CMD(task->pkt); i++)
> > > -		if (cmdq_command_is_wfe(base[i]))
> > > -			base[i] = (u64)CMDQ_JUMP_BY_OFFSET << 32 |
> > > -				  CMDQ_JUMP_PASS;
> > > -	dma_sync_single_for_device(dev, task->pa_base, task->pkt->cmd_buf_size,
> > > -				   DMA_TO_DEVICE);
> > > -}
> > > -
> > >  static bool cmdq_thread_is_in_wfe(struct cmdq_thread *thread)  {
> > >  	return readl(thread->base + CMDQ_THR_WAIT_TOKEN) & CMDQ_THR_IS_WAITING;  }
> > >  
> > > -static void cmdq_thread_wait_end(struct cmdq_thread *thread,
> > > -				 unsigned long end_pa)
> > > -{
> > > -	struct device *dev = thread->chan->mbox->dev;
> > > -	unsigned long curr_pa;
> > > -
> > > -	if (readl_poll_timeout_atomic(thread->base + CMDQ_THR_CURR_ADDR,
> > > -			curr_pa, curr_pa == end_pa, 1, 20))
> > > -		dev_err(dev, "GCE thread cannot run to end.\n");
> > > -}
> > > -
> > > -static void cmdq_task_exec_done(struct cmdq_task *task, enum cmdq_cb_status sta) -{
> > > -	struct cmdq_task_cb *cb = &task->pkt->async_cb;
> > > -	struct cmdq_cb_data data;
> > > -
> > > -	WARN_ON(cb->cb == (cmdq_async_flush_cb)NULL);
> > > -	data.sta = sta;
> > > -	data.data = cb->data;
> > > -	cb->cb(data);
> > > -
> > > -	list_del(&task->list_entry);
> > > -}
> > > -
> > > -static void cmdq_task_handle_error(struct cmdq_task *task) -{
> > > -	struct cmdq_thread *thread = task->thread;
> > > -	struct cmdq_task *next_task;
> > > -
> > > -	dev_err(task->cmdq->mbox.dev, "task 0x%p error\n", task);
> > > -	WARN_ON(cmdq_thread_suspend(task->cmdq, thread) < 0);
> > > -	next_task = list_first_entry_or_null(&thread->task_busy_list,
> > > -			struct cmdq_task, list_entry);
> > > -	if (next_task)
> > > -		writel(next_task->pa_base, thread->base + CMDQ_THR_CURR_ADDR);
> > > -	cmdq_thread_resume(thread);
> > > -}
> > > -
> > >  static void cmdq_thread_irq_handler(struct cmdq *cmdq,
> > >  				    struct cmdq_thread *thread)
> > >  {
> > > -	struct cmdq_task *task, *tmp, *curr_task = NULL;
> > > -	u32 curr_pa, irq_flag, task_end_pa;
> > > -	bool err;
> > > +	unsigned long flags;
> > > +	u32 curr_pa, irq_flag, end_pa;
> > > +	int ret = 0;
> > >  
> > > +	spin_lock_irqsave(&thread->chan->lock, flags);
> > >  	irq_flag = readl(thread->base + CMDQ_THR_IRQ_STATUS);
> > >  	writel(~irq_flag, thread->base + CMDQ_THR_IRQ_STATUS);
> > >  
> > > -	/*
> > > -	 * When ISR call this function, another CPU core could run
> > > -	 * "release task" right before we acquire the spin lock, and thus
> > > -	 * reset / disable this GCE thread, so we need to check the enable
> > > -	 * bit of this GCE thread.
> > > -	 */
> > > -	if (!(readl(thread->base + CMDQ_THR_ENABLE_TASK) & CMDQ_THR_ENABLED))
> > > -		return;
> > > -
> > > -	if (irq_flag & CMDQ_THR_IRQ_ERROR)
> > > -		err = true;
> > > -	else if (irq_flag & CMDQ_THR_IRQ_DONE)
> > > -		err = false;
> > > -	else
> > > -		return;
> > > -
> > >  	curr_pa = readl(thread->base + CMDQ_THR_CURR_ADDR);
> > > +	end_pa = readl(thread->base + CMDQ_THR_END_ADDR);
> > >  
> > > -	list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
> > > -				 list_entry) {
> > > -		task_end_pa = task->pa_base + task->pkt->cmd_buf_size;
> > > -		if (curr_pa >= task->pa_base && curr_pa < task_end_pa)
> > > -			curr_task = task;
> > > -
> > > -		if (!curr_task || curr_pa == task_end_pa - CMDQ_INST_SIZE) {
> > > -			cmdq_task_exec_done(task, CMDQ_CB_NORMAL);
> > > -			kfree(task);
> > > -		} else if (err) {
> > > -			cmdq_task_exec_done(task, CMDQ_CB_ERROR);
> > > -			cmdq_task_handle_error(curr_task);
> > > -			kfree(task);
> > > -		}
> > > -
> > > -		if (curr_task)
> > > -			break;
> > > -	}
> > > +	if (curr_pa != end_pa ||  irq_flag & CMDQ_THR_IRQ_ERROR)
> > > +		ret = -EFAULT;
> > >  
> > > -	if (list_empty(&thread->task_busy_list)) {
> > > -		cmdq_thread_disable(cmdq, thread);
> > > -		clk_disable(cmdq->clock);
> > > -	}
> > > +	thread->pkt = NULL;
> > > +	cmdq_thread_disable(cmdq, thread);
> > > +	clk_disable(cmdq->clock);
> > > +	spin_unlock_irqrestore(&thread->chan->lock, flags);
> > > +	mbox_chan_txdone(thread->chan, ret);
> > >  }
> > >  
> > >  static irqreturn_t cmdq_irq_handler(int irq, void *dev)  {
> > >  	struct cmdq *cmdq = dev;
> > > -	unsigned long irq_status, flags = 0L;
> > > +	unsigned long irq_status;
> > >  	int bit;
> > >  
> > >  	irq_status = readl(cmdq->base + CMDQ_CURR_IRQ_STATUS) & CMDQ_IRQ_MASK;
> > >  	if (!(irq_status ^ CMDQ_IRQ_MASK))
> > >  		return IRQ_NONE;
> > >  
> > > -	for_each_clear_bit(bit, &irq_status, fls(CMDQ_IRQ_MASK)) {
> > > -		struct cmdq_thread *thread = &cmdq->thread[bit];
> > > -
> > > -		spin_lock_irqsave(&thread->chan->lock, flags);
> > > -		cmdq_thread_irq_handler(cmdq, thread);
> > > -		spin_unlock_irqrestore(&thread->chan->lock, flags);
> > > -	}
> > > +	for_each_clear_bit(bit, &irq_status, fls(CMDQ_IRQ_MASK))
> > > +		cmdq_thread_irq_handler(cmdq, &cmdq->thread[bit]);
> > >  
> > >  	return IRQ_HANDLED;
> > >  }
> > > @@ -310,7 +172,7 @@ static int cmdq_suspend(struct device *dev)
> > >  
> > >  	for (i = 0; i < cmdq->thread_nr; i++) {
> > >  		thread = &cmdq->thread[i];
> > > -		if (!list_empty(&thread->task_busy_list)) {
> > > +		if (thread->pkt) {
> > >  			task_running = true;
> > >  			break;
> > >  		}
> > > @@ -347,72 +209,21 @@ static int cmdq_mbox_send_data(struct mbox_chan *chan, void *data)
> > >  	struct cmdq_pkt *pkt = (struct cmdq_pkt *)data;
> > >  	struct cmdq_thread *thread = (struct cmdq_thread *)chan->con_priv;
> > >  	struct cmdq *cmdq = dev_get_drvdata(chan->mbox->dev);
> > > -	struct cmdq_task *task;
> > > -	unsigned long curr_pa, end_pa;
> > >  
> > >  	/* Client should not flush new tasks if suspended. */
> > >  	WARN_ON(cmdq->suspended);
> > >  
> > > -	task = kzalloc(sizeof(*task), GFP_ATOMIC);
> > > -	if (!task)
> > > -		return -ENOMEM;
> > > +	thread->pkt = pkt;
> > >  
> > > -	task->cmdq = cmdq;
> > > -	INIT_LIST_HEAD(&task->list_entry);
> > > -	task->pa_base = pkt->pa_base;
> > > -	task->thread = thread;
> > > -	task->pkt = pkt;
> > > -
> > > -	if (list_empty(&thread->task_busy_list)) {
> > > -		WARN_ON(clk_enable(cmdq->clock) < 0);
> > > -		WARN_ON(cmdq_thread_reset(cmdq, thread) < 0);
> > > -
> > > -		writel(task->pa_base, thread->base + CMDQ_THR_CURR_ADDR);
> > > -		writel(task->pa_base + pkt->cmd_buf_size,
> > > -		       thread->base + CMDQ_THR_END_ADDR);
> > > -		writel(thread->priority, thread->base + CMDQ_THR_PRIORITY);
> > > -		writel(CMDQ_THR_IRQ_EN, thread->base + CMDQ_THR_IRQ_ENABLE);
> > > -		writel(CMDQ_THR_ENABLED, thread->base + CMDQ_THR_ENABLE_TASK);
> > > -	} else {
> > > -		WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> > > -		curr_pa = readl(thread->base + CMDQ_THR_CURR_ADDR);
> > > -		end_pa = readl(thread->base + CMDQ_THR_END_ADDR);
> > > -
> > > -		/*
> > > -		 * Atomic execution should remove the following wfe, i.e. only
> > > -		 * wait event at first task, and prevent to pause when running.
> > > -		 */
> > > -		if (thread->atomic_exec) {
> > > -			/* GCE is executing if command is not WFE */
> > > -			if (!cmdq_thread_is_in_wfe(thread)) {
> > > -				cmdq_thread_resume(thread);
> > > -				cmdq_thread_wait_end(thread, end_pa);
> > > -				WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> > > -				/* set to this task directly */
> > > -				writel(task->pa_base,
> > > -				       thread->base + CMDQ_THR_CURR_ADDR);
> > > -			} else {
> > > -				cmdq_task_insert_into_thread(task);
> > > -				cmdq_task_remove_wfe(task);
> > > -				smp_mb(); /* modify jump before enable thread */
> > > -			}
> > > -		} else {
> > > -			/* check boundary */
> > > -			if (curr_pa == end_pa - CMDQ_INST_SIZE ||
> > > -			    curr_pa == end_pa) {
> > > -				/* set to this task directly */
> > > -				writel(task->pa_base,
> > > -				       thread->base + CMDQ_THR_CURR_ADDR);
> > > -			} else {
> > > -				cmdq_task_insert_into_thread(task);
> > > -				smp_mb(); /* modify jump before enable thread */
> > > -			}
> > > -		}
> > > -		writel(task->pa_base + pkt->cmd_buf_size,
> > > -		       thread->base + CMDQ_THR_END_ADDR);
> > > -		cmdq_thread_resume(thread);
> > > -	}
> > > -	list_move_tail(&task->list_entry, &thread->task_busy_list);
> > > +	WARN_ON(clk_enable(cmdq->clock) < 0);
> > > +	WARN_ON(cmdq_thread_reset(cmdq, thread) < 0);
> > > +
> > > +	writel(thread->pkt->pa_base, thread->base + CMDQ_THR_CURR_ADDR);
> > > +	writel(thread->pkt->pa_base + pkt->cmd_buf_size,
> > > +	       thread->base + CMDQ_THR_END_ADDR);
> > > +	writel(thread->priority, thread->base + CMDQ_THR_PRIORITY);
> > > +	writel(CMDQ_THR_IRQ_EN, thread->base + CMDQ_THR_IRQ_ENABLE);
> > > +	writel(CMDQ_THR_ENABLED, thread->base + CMDQ_THR_ENABLE_TASK);
> > >  
> > >  	return 0;
> > >  }
> > > @@ -421,23 +232,18 @@ static void cmdq_mbox_abort_data(struct mbox_chan *chan)  {
> > >  	struct cmdq_thread *thread = (struct cmdq_thread *)chan->con_priv;
> > >  	struct cmdq *cmdq = dev_get_drvdata(chan->mbox->dev);
> > > -	struct cmdq_task *task, *tmp;
> > >  	unsigned long flags;
> > >  	u32 enable;
> > >  
> > >  	spin_lock_irqsave(&thread->chan->lock, flags);
> > > -	if (list_empty(&thread->task_busy_list))
> > > +	if (!thread->pkt)
> > >  		goto out;
> > >  
> > >  	WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> > >  	if (!cmdq_thread_is_in_wfe(thread))
> > >  		goto wait;
> > >  
> > > -	list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
> > > -				 list_entry) {
> > > -		list_del(&task->list_entry);
> > > -		kfree(task);
> > > -	}
> > > +	thread->pkt = NULL;
> > >  
> > >  	cmdq_thread_resume(thread);
> > >  	cmdq_thread_disable(cmdq, thread);
> > > @@ -483,7 +289,6 @@ static struct mbox_chan *cmdq_xlate(struct mbox_controller *mbox,
> > >  
> > >  	thread = (struct cmdq_thread *)mbox->chans[ind].con_priv;
> > >  	thread->priority = sp->args[1];
> > > -	thread->atomic_exec = (sp->args[2] != 0);
> > >  	thread->chan = &mbox->chans[ind];
> > >  
> > >  	return &mbox->chans[ind];
> > > @@ -539,8 +344,7 @@ static int cmdq_probe(struct platform_device *pdev)
> > >  	cmdq->mbox.ops = &cmdq_mbox_chan_ops;
> > >  	cmdq->mbox.of_xlate = cmdq_xlate;
> > >  
> > > -	/* make use of TXDONE_BY_ACK */
> > > -	cmdq->mbox.txdone_irq = false;
> > > +	cmdq->mbox.txdone_irq = true;
> > >  	cmdq->mbox.txdone_poll = false;
> > >  
> > >  	cmdq->thread = devm_kcalloc(dev, cmdq->thread_nr, @@ -551,7 +355,6 @@ static int cmdq_probe(struct platform_device *pdev)
> > >  	for (i = 0; i < cmdq->thread_nr; i++) {
> > >  		cmdq->thread[i].base = cmdq->base + CMDQ_THR_BASE +
> > >  				CMDQ_THR_SIZE * i;
> > > -		INIT_LIST_HEAD(&cmdq->thread[i].task_busy_list);
> > >  		cmdq->mbox.chans[i].con_priv = (void *)&cmdq->thread[i];
> > >  	}
> > >  
> > > --
> > > 2.18.1
> > > 
> > 
> > 
> 
> 

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