RE: [PATCH v2 4/4] dmaengine: xilinx_vdma: Improve channel idle checking

[Appana Durga Kedareswara Rao]

Hi Vinod,

> -----Original Message-----
> From: Vinod Koul [mailto:vinod.koul@xxxxxxxxx]
> Sent: Tuesday, February 23, 2016 8:42 AM
> To: Appana Durga Kedareswara Rao
> Cc: dan.j.williams@xxxxxxxxx; Michal Simek; Soren Brinkmann; Appana Durga
> Kedareswara Rao; moritz.fischer@xxxxxxxxx;
> laurent.pinchart@xxxxxxxxxxxxxxxx; luis@xxxxxxxxxxxxxxxxx; Anirudha
> Sarangi; dmaengine@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 4/4] dmaengine: xilinx_vdma: Improve channel idle
> checking
> 
> On Mon, Feb 22, 2016 at 11:24:37AM +0530, Kedareswara rao Appana wrote:
> > This patch improves the channel idle cheking by introduing
> 				      ^^^^^^^^^
> typo

Ok will fix.

> 
> > a new varibale in chan private structure.
> 	^^^^^^^
> here too :(

Ok will fix.

> 
> and there is no description how this improvement is achieved and why

Ok will give detailed explanation in the next version of the patch.

Regards,
Kedar.

> >
> > Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
> > ---
> > Changes for v2:
> > ---> splitted the changes into multiple patches.
> >
> >  drivers/dma/xilinx/xilinx_vdma.c | 41
> > ++++++++--------------------------------
> >  1 file changed, 8 insertions(+), 33 deletions(-)
> >
> > diff --git a/drivers/dma/xilinx/xilinx_vdma.c
> > b/drivers/dma/xilinx/xilinx_vdma.c
> > index 8db07f7..51686d1 100644
> > --- a/drivers/dma/xilinx/xilinx_vdma.c
> > +++ b/drivers/dma/xilinx/xilinx_vdma.c
> > @@ -202,6 +202,7 @@ struct xilinx_vdma_tx_descriptor {
> >   * @has_sg: Support scatter transfers
> >   * @genlock: Support genlock mode
> >   * @err: Channel has errors
> > + * @idle: Check for channel idle
> >   * @tasklet: Cleanup work after irq
> >   * @config: Device configuration info
> >   * @flush_on_fsync: Flush on Frame sync @@ -225,6 +226,7 @@ struct
> > xilinx_vdma_chan {
> >  	bool has_sg;
> >  	bool genlock;
> >  	bool err;
> > +	bool idle;
> >  	struct tasklet_struct tasklet;
> >  	struct xilinx_vdma_config config;
> >  	bool flush_on_fsync;
> > @@ -519,32 +521,6 @@ static enum dma_status
> > xilinx_vdma_tx_status(struct dma_chan *dchan,  }
> >
> >  /**
> > - * xilinx_vdma_is_running - Check if VDMA channel is running
> > - * @chan: Driver specific VDMA channel
> > - *
> > - * Return: '1' if running, '0' if not.
> > - */
> > -static bool xilinx_vdma_is_running(struct xilinx_vdma_chan *chan) -{
> > -	return !(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
> > -		 XILINX_VDMA_DMASR_HALTED) &&
> > -		(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR) &
> > -		 XILINX_VDMA_DMACR_RUNSTOP);
> > -}
> > -
> > -/**
> > - * xilinx_vdma_is_idle - Check if VDMA channel is idle
> > - * @chan: Driver specific VDMA channel
> > - *
> > - * Return: '1' if idle, '0' if not.
> > - */
> > -static bool xilinx_vdma_is_idle(struct xilinx_vdma_chan *chan) -{
> > -	return vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
> > -		XILINX_VDMA_DMASR_IDLE;
> > -}
> > -
> > -/**
> >   * xilinx_vdma_halt - Halt VDMA channel
> >   * @chan: Driver specific VDMA channel
> >   */
> > @@ -614,6 +590,9 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_vdma_chan *chan)
> >  	if (list_empty(&chan->pending_list))
> >  		return;
> >
> > +	if (!chan->idle)
> > +		return;
> > +
> >  	desc = list_first_entry(&chan->pending_list,
> >  				struct xilinx_vdma_tx_descriptor, node);
> >  	tail_desc = list_last_entry(&chan->pending_list,
> > @@ -622,13 +601,6 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_vdma_chan *chan)
> >  	tail_segment = list_last_entry(&tail_desc->segments,
> >  				       struct xilinx_vdma_tx_segment, node);
> >
> > -	/* If it is SG mode and hardware is busy, cannot submit */
> > -	if (chan->has_sg && xilinx_vdma_is_running(chan) &&
> > -	    !xilinx_vdma_is_idle(chan)) {
> > -		dev_dbg(chan->dev, "DMA controller still busy\n");
> > -		return;
> > -	}
> > -
> >  	/*
> >  	 * If hardware is idle, then all descriptors on the running lists are
> >  	 * done, start new transfers
> > @@ -708,6 +680,7 @@ static void xilinx_vdma_start_transfer(struct
> > xilinx_vdma_chan *chan)
> >
> >  	list_splice_tail_init(&chan->pending_list, &chan->active_list);
> >  	chan->desc_pendingcount = 0;
> > +	chan->idle = false;
> >  }
> >
> >  /**
> > @@ -854,6 +827,7 @@ static irqreturn_t xilinx_vdma_irq_handler(int irq, void
> *data)
> >  	if (status & XILINX_VDMA_DMASR_FRM_CNT_IRQ) {
> >  		spin_lock(&chan->lock);
> >  		xilinx_vdma_complete_descriptor(chan);
> > +		chan->idle = true;
> >  		xilinx_vdma_start_transfer(chan);
> >  		spin_unlock(&chan->lock);
> >  	}
> > @@ -1212,6 +1186,7 @@ static int xilinx_vdma_chan_probe(struct
> > xilinx_vdma_device *xdev,
> >
> >  	list_add_tail(&chan->common.device_node, &xdev-
> >common.channels);
> >  	xdev->chan[chan->id] = chan;
> > +	chan->idle = true;
> >
> >  	/* Reset the channel */
> >  	err = xilinx_vdma_chan_reset(chan);
> > --
> > 2.1.2
> >
> 
> --
> ~Vinod