[2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet

[2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet

[Vinod Koul]

On 05-02-19, 12:03, Nicolas Ferre wrote:
> Complement the identification of errors with stoping the channel and
> dumping the descriptor that led to the error case.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> ---
>  drivers/dma/at_xdmac.c | 43 ++++++++++++++++++++++++++++++++++++------
>  1 file changed, 37 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index 37a269420435..ec7a29d8e448 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -1575,6 +1575,41 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
>  		dmaengine_desc_get_callback_invoke(txd, NULL);
>  }
>  
> +static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
> +{
> +	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
> +	struct at_xdmac_desc	*bad_desc;
> +
> +	/*
> +	 * The descriptor currently at the head of the active list is
> +	 * broked. Since we don't have any way to report errors, we'll

You meant borked or broken... 

> +	 * just have to scream loudly and try to carry on.

should we carry on or abort..?

> +	 */
> +	if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
> +		dev_err(chan2dev(&atchan->chan), "read bus error!!!");
> +	if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
> +		dev_err(chan2dev(&atchan->chan), "write bus error!!!");
> +	if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
> +		dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
> +
> +	spin_lock_bh(&atchan->lock);
> +	/* Channel must be disabled first as it's not done automatically */
> +	at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
> +	while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
> +		cpu_relax();
> +	bad_desc = list_first_entry(&atchan->xfers_list,
> +				    struct at_xdmac_desc,
> +				    xfer_node);
> +	spin_unlock_bh(&atchan->lock);
> +	/* Print bad descriptor's details if needed */

Well this is not great to look and read at, please do consider adding
empty line before comments or logical blocks..

> +	dev_dbg(chan2dev(&atchan->chan),
> +		 "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
> +		 __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
> +		 bad_desc->lld.mbr_ubc);

not dev_err?

> +
> +	/* Then continue with usual descriptor management */
> +}
> +
>  static void at_xdmac_tasklet(unsigned long data)
>  {
>  	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
> @@ -1594,12 +1629,8 @@ static void at_xdmac_tasklet(unsigned long data)
>  		   || (atchan->irq_status & error_mask)) {
>  		struct dma_async_tx_descriptor  *txd;
>  
> -		if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
> -			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
> -		if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
> -			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
> -		if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
> -			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
> +		if (atchan->irq_status & error_mask)
> +			at_xdmac_handle_error(atchan);
>  
>  		spin_lock(&atchan->lock);
>  		desc = list_first_entry(&atchan->xfers_list,
> -- 
> 2.17.1

[2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet

[Nicolas Ferre]

Vinod,

Thanks for your review, I'm preparing v2.

On 11/02/2019 at 12:58, Vinod Koul wrote:
> On 05-02-19, 12:03, Nicolas Ferre wrote:
>> Complement the identification of errors with stoping the channel and
>> dumping the descriptor that led to the error case.
>>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
>> ---
>>   drivers/dma/at_xdmac.c | 43 ++++++++++++++++++++++++++++++++++++------
>>   1 file changed, 37 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
>> index 37a269420435..ec7a29d8e448 100644
>> --- a/drivers/dma/at_xdmac.c
>> +++ b/drivers/dma/at_xdmac.c
>> @@ -1575,6 +1575,41 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
>>   		dmaengine_desc_get_callback_invoke(txd, NULL);
>>   }
>>   
>> +static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
>> +{
>> +	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
>> +	struct at_xdmac_desc	*bad_desc;
>> +
>> +	/*
>> +	 * The descriptor currently at the head of the active list is
>> +	 * broked. Since we don't have any way to report errors, we'll
> 
> You meant borked or broken...

Broken

> 
>> +	 * just have to scream loudly and try to carry on.
> 
> should we carry on or abort..?

Changed in:

  * just have to scream loudly and try to continue with other
  * descriptors queued (if any).

>> +	 */
>> +	if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
>> +		dev_err(chan2dev(&atchan->chan), "read bus error!!!");
>> +	if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
>> +		dev_err(chan2dev(&atchan->chan), "write bus error!!!");
>> +	if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
>> +		dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
>> +
>> +	spin_lock_bh(&atchan->lock);
>> +	/* Channel must be disabled first as it's not done automatically */
>> +	at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
>> +	while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
>> +		cpu_relax();
>> +	bad_desc = list_first_entry(&atchan->xfers_list,
>> +				    struct at_xdmac_desc,
>> +				    xfer_node);
>> +	spin_unlock_bh(&atchan->lock);
>> +	/* Print bad descriptor's details if needed */
> 
> Well this is not great to look and read at, please do consider adding
> empty line before comments or logical blocks..

True, indeed.

>> +	dev_dbg(chan2dev(&atchan->chan),
>> +		 "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
>> +		 __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
>> +		 bad_desc->lld.mbr_ubc);
> 
> not dev_err?

Well, we have the dev_err at the beginning of the function, I think it's 
enough: this is really debugging information that needs to be activated 
to track the DMA configuration bug: it's not meant for production.

>> +
>> +	/* Then continue with usual descriptor management */
>> +}
>> +
>>   static void at_xdmac_tasklet(unsigned long data)
>>   {
>>   	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
>> @@ -1594,12 +1629,8 @@ static void at_xdmac_tasklet(unsigned long data)
>>   		   || (atchan->irq_status & error_mask)) {
>>   		struct dma_async_tx_descriptor  *txd;
>>   
>> -		if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
>> -			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
>> -		if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
>> -			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
>> -		if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
>> -			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
>> +		if (atchan->irq_status & error_mask)
>> +			at_xdmac_handle_error(atchan);
>>   
>>   		spin_lock(&atchan->lock);
>>   		desc = list_first_entry(&atchan->xfers_list,
>> -- 
>> 2.17.1
> 


-- 
Nicolas Ferre

[2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet

[Ludovic Desroches]

On Tue, Feb 05, 2019 at 12:03:42PM +0100, Nicolas Ferre wrote:
> Complement the identification of errors with stoping the channel and
> dumping the descriptor that led to the error case.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

> ---
>  drivers/dma/at_xdmac.c | 43 ++++++++++++++++++++++++++++++++++++------
>  1 file changed, 37 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index 37a269420435..ec7a29d8e448 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -1575,6 +1575,41 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
>  		dmaengine_desc_get_callback_invoke(txd, NULL);
>  }
>  
> +static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
> +{
> +	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
> +	struct at_xdmac_desc	*bad_desc;
> +
> +	/*
> +	 * The descriptor currently at the head of the active list is
> +	 * broked. Since we don't have any way to report errors, we'll
> +	 * just have to scream loudly and try to carry on.
> +	 */
> +	if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
> +		dev_err(chan2dev(&atchan->chan), "read bus error!!!");
> +	if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
> +		dev_err(chan2dev(&atchan->chan), "write bus error!!!");
> +	if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
> +		dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
> +
> +	spin_lock_bh(&atchan->lock);
> +	/* Channel must be disabled first as it's not done automatically */
> +	at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
> +	while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
> +		cpu_relax();
> +	bad_desc = list_first_entry(&atchan->xfers_list,
> +				    struct at_xdmac_desc,
> +				    xfer_node);
> +	spin_unlock_bh(&atchan->lock);
> +	/* Print bad descriptor's details if needed */
> +	dev_dbg(chan2dev(&atchan->chan),
> +		 "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
> +		 __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
> +		 bad_desc->lld.mbr_ubc);
> +
> +	/* Then continue with usual descriptor management */
> +}
> +
>  static void at_xdmac_tasklet(unsigned long data)
>  {
>  	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
> @@ -1594,12 +1629,8 @@ static void at_xdmac_tasklet(unsigned long data)
>  		   || (atchan->irq_status & error_mask)) {
>  		struct dma_async_tx_descriptor  *txd;
>  
> -		if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
> -			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
> -		if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
> -			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
> -		if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
> -			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
> +		if (atchan->irq_status & error_mask)
> +			at_xdmac_handle_error(atchan);
>  
>  		spin_lock(&atchan->lock);
>  		desc = list_first_entry(&atchan->xfers_list,
> -- 
> 2.17.1
>

[2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet

[Nicolas Ferre]

Complement the identification of errors with stoping the channel and
dumping the descriptor that led to the error case.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
---
 drivers/dma/at_xdmac.c | 43 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 37a269420435..ec7a29d8e448 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -1575,6 +1575,41 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
 		dmaengine_desc_get_callback_invoke(txd, NULL);
 }
 
+static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
+{
+	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
+	struct at_xdmac_desc	*bad_desc;
+
+	/*
+	 * The descriptor currently at the head of the active list is
+	 * broked. Since we don't have any way to report errors, we'll
+	 * just have to scream loudly and try to carry on.
+	 */
+	if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
+		dev_err(chan2dev(&atchan->chan), "read bus error!!!");
+	if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
+		dev_err(chan2dev(&atchan->chan), "write bus error!!!");
+	if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
+		dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
+
+	spin_lock_bh(&atchan->lock);
+	/* Channel must be disabled first as it's not done automatically */
+	at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
+	while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
+		cpu_relax();
+	bad_desc = list_first_entry(&atchan->xfers_list,
+				    struct at_xdmac_desc,
+				    xfer_node);
+	spin_unlock_bh(&atchan->lock);
+	/* Print bad descriptor's details if needed */
+	dev_dbg(chan2dev(&atchan->chan),
+		 "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
+		 __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
+		 bad_desc->lld.mbr_ubc);
+
+	/* Then continue with usual descriptor management */
+}
+
 static void at_xdmac_tasklet(unsigned long data)
 {
 	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
@@ -1594,12 +1629,8 @@ static void at_xdmac_tasklet(unsigned long data)
 		   || (atchan->irq_status & error_mask)) {
 		struct dma_async_tx_descriptor  *txd;
 
-		if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
-			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
-		if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
-			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
-		if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
-			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
+		if (atchan->irq_status & error_mask)
+			at_xdmac_handle_error(atchan);
 
 		spin_lock(&atchan->lock);
 		desc = list_first_entry(&atchan->xfers_list,