linux-kernel - Re: [PATCH RESEND 1/2] dmaengine: dw-edma: Move "Set consumer cycle" into first condition in dw_hdma_v0_core

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Message-ID: <20240721085723.GN1908@thinkpad>
Date: Sun, 21 Jul 2024 14:27:23 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: dongxiong zheng <zhengdongxiong@...icro.cn>
Cc: dmaengine@...r.kernel.org, fancer.lancer@...il.com,
	linux-kernel@...r.kernel.org, vkoul@...nel.org
Subject: Re: [PATCH RESEND 1/2] dmaengine: dw-edma: Move "Set consumer cycle"
 into first condition in dw_hdma_v0_core_start()

On Sat, Jul 06, 2024 at 04:40:10PM +0800, dongxiong zheng wrote:
> Hi, Manivannan Sadhasivam:
> 	Thank you for your reply!
> 
> On Fri, Jul 05, 2024 at 19:42:41 +0530, Manivannan Sadhasivam wrote:
> > On Fri, Jul 05, 2024 at 06:57:34PM +0800, zheng.dongxiong wrote:
> > > Two or more chunks are used in a transfer,
> > > Consumer cycle only needs to be set on the first transfer.
> > >
> >
> > Can you please reference the section of the spec that mentions this behavior?
> >
> > - Mani
> >
> 
> Reference:
> 	Chapter 6.4.9.1 LL Operation Overview:
> 	"Figure 6-23 Linked List Flow for Producer and Consumer" in
> 	DesignWare Cores PCI Express Controller Databook (Version 6.00a June 2022)
> 
> The CCS must be set when L1 is executed for the first time, After an interruption is
> triggered, CCS does not need to be configured again when L3 is executed.
> 

Okay, please include this reference in commit message and send v2.

- Mani

> > > Signed-off-by: zheng.dongxiong <zheng.dongxiong@...look.com>
> > > ---
> > >  drivers/dma/dw-edma/dw-hdma-v0-core.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> > > index 10e8f0715..d77051d1e 100644
> > > --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> > > +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> > > @@ -262,10 +262,10 @@ static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> > >  			  lower_32_bits(chunk->ll_region.paddr));
> > >  		SET_CH_32(dw, chan->dir, chan->id, llp.msb,
> > >  			  upper_32_bits(chunk->ll_region.paddr));
> > > +		/* Set consumer cycle */
> > > +		SET_CH_32(dw, chan->dir, chan->id, cycle_sync,
> > > +			HDMA_V0_CONSUMER_CYCLE_STAT | HDMA_V0_CONSUMER_CYCLE_BIT);
> > >  	}
> > > -	/* Set consumer cycle */
> > > -	SET_CH_32(dw, chan->dir, chan->id, cycle_sync,
> > > -		  HDMA_V0_CONSUMER_CYCLE_STAT | HDMA_V0_CONSUMER_CYCLE_BIT);
> > >
> > >  	dw_hdma_v0_sync_ll_data(chunk);
> > >
> > > --
> > > 2.34.1
> > >
> >
> 
> Test brief: hdma set chan->ll_max == 1,
> then user alloc two or more scatterlist, start transfer.
> 
> --
> Regards,
> dongxiong zheng
> 

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