linux-kernel - Re: [PATCH 1/3] dmaengine: dw-axi-dmac: dump channel registers on error

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Message-ID: <YtlG6hdTJPIDBk9Y@matsya>
Date:   Thu, 21 Jul 2022 18:00:34 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Ben Dooks <ben.dooks@...ive.com>
Cc:     dmaengine@...r.kernel.org, Eugeniy.Paltsev@...opsys.com,
        linux-kernel@...r.kernel.org,
        Sudip Mukherjee <sudip.mukherjee@...ive.com>,
        Jude Onyenegecha <jude.onyenegecha@...ive.com>
Subject: Re: [PATCH 1/3] dmaengine: dw-axi-dmac: dump channel registers on
 error

On 08-07-22, 18:01, Ben Dooks wrote:
> On channel error, dump the channel register state before
> the channel's LLI entries to see what the controller was
> actually doing when the error happend.
> 
> Signed-off-by: Ben Dooks <ben.dooks@...ive.com>
> ---
>  .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> index e9c9bcb1f5c2..75c537153e92 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -79,6 +79,20 @@ axi_chan_iowrite64(struct axi_dma_chan *chan, u32 reg, u64 val)
>  	iowrite32(upper_32_bits(val), chan->chan_regs + reg + 4);
>  }
>  
> +static inline u64
> +axi_chan_ioread64(struct axi_dma_chan *chan, u32 reg)
> +{
> +	u32 high, low;
> +	u64 result;
> +
> +	low = ioread32(chan->chan_regs + reg);
> +	high = ioread32(chan->chan_regs + reg + 4);
> +
> +	result = low;
> +	result |= (u64)high << 32;
> +	return result;
> +}

Better to use helpers like lo_hi_readq()?

> +
>  static inline void axi_chan_config_write(struct axi_dma_chan *chan,
>  					 struct axi_dma_chan_config *config)
>  {
> @@ -979,6 +993,18 @@ static int dw_axi_dma_chan_slave_config(struct dma_chan *dchan,
>  	return 0;
>  }
>  
> +static void axi_chan_dump_regs(struct axi_dma_chan *chan)
> +{
> +	dev_err(dchan2dev(&chan->vc.chan),
> +		"R: SAR: 0x%llx DAR: 0x%llx LLP: 0x%llx BTS 0x%x CTL: 0x%x:%08x\n",
> +		axi_chan_ioread64(chan, CH_SAR),
> +		axi_chan_ioread64(chan, CH_DAR),
> +		axi_chan_ioread64(chan, CH_LLP),
> +		axi_chan_ioread32(chan, CH_BLOCK_TS),
> +		axi_chan_ioread32(chan, CH_CTL_H),
> +		axi_chan_ioread32(chan, CH_CTL_L));
> +}
> +
>  static void axi_chan_dump_lli(struct axi_dma_chan *chan,
>  			      struct axi_dma_hw_desc *desc)
>  {
> @@ -1020,6 +1046,8 @@ static noinline void axi_chan_handle_err(struct axi_dma_chan *chan, u32 status)
>  	dev_err(chan2dev(chan),
>  		"Bad descriptor submitted for %s, cookie: %d, irq: 0x%08x\n",
>  		axi_chan_name(chan), vd->tx.cookie, status);
> +
> +	axi_chan_dump_regs(chan);
>  	axi_chan_list_dump_lli(chan, vd_to_axi_desc(vd));
>  
>  	vchan_cookie_complete(vd);
> -- 
> 2.35.1

-- 
~Vinod