[PATCH v4] dmaengine: loongson: Remove the dev_dbg() output

[PATCH v4] dmaengine: loongson: Remove the dev_dbg() output

[Sebastian Andrzej Siewior]

The %pK format modifier was meant for /proc kind of output, not general
printk output. Since commit ad67b74d2469d ("printk: hash addresses
printed with %p") pointers are hashed by default and the behaviour can
be controller by `hash_pointers' boot argument.
The policy on %p is to not introduce new ones.

The output in loongson2_cmc_dma_issue_pending() is the only dev_dbg()
output in the driver and is only output once the transfer is started.
There is no output issued by the driver if the transfer is completed, if
a follow-up transfer is started or if any of the other callbacks (such
as loongson2_cmc_dma_tx_status()) are invoked. This output does not look
essential.

Instead removing just the %pK output, remove the complete dev_dbg()
output from the driver.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v3…v4: https://lore.kernel.org/all/20260921151312.I8Q8NLnx@linutronix.de/
  - Drop the braces now that there is a single statement left.

v2…v3: https://lore.kernel.org/all/20260918201714.eFNI3VMq@linutronix.de/
  - Reword part of the commit message.

v1…v2: https://lore.kernel.org/all/20260918103409.UV4g2ON7@linutronix.de/
  - Update subject line (it is removed, not replaced).

 drivers/dma/loongson/loongson2-apb-cmc-dma.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/dma/loongson/loongson2-apb-cmc-dma.c b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
index 1c9a542edc859..93727ae972ae2 100644
--- a/drivers/dma/loongson/loongson2-apb-cmc-dma.c
+++ b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
@@ -336,10 +336,8 @@ static void loongson2_cmc_dma_issue_pending(struct dma_chan *chan)
 
 	guard(spinlock_irqsave)(&lchan->vchan.lock);
 
-	if (vchan_issue_pending(&lchan->vchan) && !lchan->desc) {
-		dev_dbg(chan2dev(lchan), "vchan %pK: issued\n", &lchan->vchan);
+	if (vchan_issue_pending(&lchan->vchan) && !lchan->desc)
 		loongson2_cmc_dma_start_transfer(lchan);
-	}
 }
 
 static int loongson2_cmc_dma_set_xfer_param(struct loongson2_cmc_dma_chan *lchan,
-- 
2.55.0

Re: [PATCH v4] dmaengine: loongson: Remove the dev_dbg() output

[Binbin Zhou]

Hi:

Thanks for your patch.

On 2026/9/22 03:57, Sebastian Andrzej Siewior wrote:
> The %pK format modifier was meant for /proc kind of output, not general
> printk output. Since commit ad67b74d2469d ("printk: hash addresses
> printed with %p") pointers are hashed by default and the behaviour can
> be controller by `hash_pointers' boot argument.
> The policy on %p is to not introduce new ones.
> 
> The output in loongson2_cmc_dma_issue_pending() is the only dev_dbg()
> output in the driver and is only output once the transfer is started.
> There is no output issued by the driver if the transfer is completed, if
> a follow-up transfer is started or if any of the other callbacks (such
> as loongson2_cmc_dma_tx_status()) are invoked. This output does not look
> essential.
> 
> Instead removing just the %pK output, remove the complete dev_dbg()
> output from the driver.
> 
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Binbin Zhou <zhoubinbin@loongson.cn>

> ---
> v3…v4: https://lore.kernel.org/all/20260921151312.I8Q8NLnx@linutronix.de/
>    - Drop the braces now that there is a single statement left.
> 
> v2…v3: https://lore.kernel.org/all/20260918201714.eFNI3VMq@linutronix.de/
>    - Reword part of the commit message.
> 
> v1…v2: https://lore.kernel.org/all/20260918103409.UV4g2ON7@linutronix.de/
>    - Update subject line (it is removed, not replaced).
> 
>   drivers/dma/loongson/loongson2-apb-cmc-dma.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/loongson/loongson2-apb-cmc-dma.c b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
> index 1c9a542edc859..93727ae972ae2 100644
> --- a/drivers/dma/loongson/loongson2-apb-cmc-dma.c
> +++ b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
> @@ -336,10 +336,8 @@ static void loongson2_cmc_dma_issue_pending(struct dma_chan *chan)
>   
>   	guard(spinlock_irqsave)(&lchan->vchan.lock);
>   
> -	if (vchan_issue_pending(&lchan->vchan) && !lchan->desc) {
> -		dev_dbg(chan2dev(lchan), "vchan %pK: issued\n", &lchan->vchan);
> +	if (vchan_issue_pending(&lchan->vchan) && !lchan->desc)
>   		loongson2_cmc_dma_start_transfer(lchan);
> -	}
>   }
>   
>   static int loongson2_cmc_dma_set_xfer_param(struct loongson2_cmc_dma_chan *lchan,

-- 
Thanks.
Binbin

Re: [PATCH v4] dmaengine: loongson: Remove the dev_dbg() output

[Vinod Koul]

On 21-09-26, 21:57, Sebastian Andrzej Siewior wrote:
> The %pK format modifier was meant for /proc kind of output, not general
> printk output. Since commit ad67b74d2469d ("printk: hash addresses
> printed with %p") pointers are hashed by default and the behaviour can
> be controller by `hash_pointers' boot argument.
> The policy on %p is to not introduce new ones.
> 
> The output in loongson2_cmc_dma_issue_pending() is the only dev_dbg()
> output in the driver and is only output once the transfer is started.
> There is no output issued by the driver if the transfer is completed, if
> a follow-up transfer is started or if any of the other callbacks (such
> as loongson2_cmc_dma_tx_status()) are invoked. This output does not look
> essential.
> 
> Instead removing just the %pK output, remove the complete dev_dbg()
> output from the driver.

This doesnt apply against the current code, pls rebase

-- 
~Vinod