dw-axi-dmac updates (debug, minor bugfixes)

dw-axi-dmac updates (debug, minor bugfixes)

[Ben Dooks]

During some recent testing, it was useful to have a dump of the
registers during an channel dump and a couple of minor bugs were
found with issues where a slow response or race condition occured.

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

[Ben Dooks]

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@sifive.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;
+}
+
 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

[PATCH 2/3] dmaengine: dw-axi-dmac: do not print NULL LLI during error

[Ben Dooks]

During debugging we have seen an issue where axi_chan_dump_lli()
is passed a NULL LLI pointer which ends up causing an OOPS due
to trying to get fields from it. Simply print NULL LLI and exit
to avoid this.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
---
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 5 +++++
 1 file changed, 5 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 75c537153e92..d6ef5f49f281 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1008,6 +1008,11 @@ static void axi_chan_dump_regs(struct axi_dma_chan *chan)
 static void axi_chan_dump_lli(struct axi_dma_chan *chan,
 			      struct axi_dma_hw_desc *desc)
 {
+	if (!desc->lli) {
+		dev_err(dchan2dev(&chan->vc.chan), "NULL LLI\n");
+		return;
+	}
+
 	dev_err(dchan2dev(&chan->vc.chan),
 		"SAR: 0x%llx DAR: 0x%llx LLP: 0x%llx BTS 0x%x CTL: 0x%x:%08x",
 		le64_to_cpu(desc->lli->sar),
-- 
2.35.1

[PATCH 3/3] dmaengine: dw-axi-dmac: ignore interrupt if no descriptor

[Ben Dooks]

If the channel has no descriptor and the interrupt is raised then the
kernel will OOPS. Check the result of vchan_next_desc() in the handler
axi_chan_block_xfer_complete() to avoid the error happening.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
---
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 6 ++++++
 1 file changed, 6 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 d6ef5f49f281..1fedf4376678 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1082,6 +1082,11 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
 
 	/* The completed descriptor currently is in the head of vc list */
 	vd = vchan_next_desc(&chan->vc);
+	if (!vd) {
+		dev_err(chan2dev(chan), "BUG: %s, IRQ with no descriptors\n",
+			axi_chan_name(chan));
+		goto out;
+	}
 
 	if (chan->cyclic) {
 		desc = vd_to_axi_desc(vd);
@@ -1111,6 +1116,7 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
 		axi_chan_start_first_queued(chan);
 	}
 
+out:
 	spin_unlock_irqrestore(&chan->vc.lock, flags);
 }
 
-- 
2.35.1

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

[Vinod Koul]

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@sifive.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

Re: [PATCH 2/3] dmaengine: dw-axi-dmac: do not print NULL LLI during error

[Vinod Koul]

On 08-07-22, 18:01, Ben Dooks wrote:
> During debugging we have seen an issue where axi_chan_dump_lli()
> is passed a NULL LLI pointer which ends up causing an OOPS due
> to trying to get fields from it. Simply print NULL LLI and exit
> to avoid this.

Applied, thanks

> 
> Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
> ---
>  drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 5 +++++
>  1 file changed, 5 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 75c537153e92..d6ef5f49f281 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -1008,6 +1008,11 @@ static void axi_chan_dump_regs(struct axi_dma_chan *chan)
>  static void axi_chan_dump_lli(struct axi_dma_chan *chan,
>  			      struct axi_dma_hw_desc *desc)
>  {
> +	if (!desc->lli) {
> +		dev_err(dchan2dev(&chan->vc.chan), "NULL LLI\n");
> +		return;
> +	}
> +
>  	dev_err(dchan2dev(&chan->vc.chan),
>  		"SAR: 0x%llx DAR: 0x%llx LLP: 0x%llx BTS 0x%x CTL: 0x%x:%08x",
>  		le64_to_cpu(desc->lli->sar),
> -- 
> 2.35.1

-- 
~Vinod

Re: [PATCH 3/3] dmaengine: dw-axi-dmac: ignore interrupt if no descriptor

[Vinod Koul]

On 08-07-22, 18:01, Ben Dooks wrote:
> If the channel has no descriptor and the interrupt is raised then the
> kernel will OOPS. Check the result of vchan_next_desc() in the handler
> axi_chan_block_xfer_complete() to avoid the error happening.

Applied, thanks

> 
> Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
> ---
>  drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 6 ++++++
>  1 file changed, 6 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 d6ef5f49f281..1fedf4376678 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -1082,6 +1082,11 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
>  
>  	/* The completed descriptor currently is in the head of vc list */
>  	vd = vchan_next_desc(&chan->vc);
> +	if (!vd) {
> +		dev_err(chan2dev(chan), "BUG: %s, IRQ with no descriptors\n",
> +			axi_chan_name(chan));
> +		goto out;
> +	}
>  
>  	if (chan->cyclic) {
>  		desc = vd_to_axi_desc(vd);
> @@ -1111,6 +1116,7 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
>  		axi_chan_start_first_queued(chan);
>  	}
>  
> +out:
>  	spin_unlock_irqrestore(&chan->vc.lock, flags);
>  }
>  
> -- 
> 2.35.1

-- 
~Vinod

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

[Ben Dooks]

On 21/07/2022 13:30, Vinod Koul wrote:
> 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@sifive.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()?

Will go check on those, thanks.