[PATCH v2] dmaengine: qcom_hidma: Remove useless DMA-32 fallback configuration

[PATCH v2] dmaengine: qcom_hidma: Remove useless DMA-32 fallback configuration

[Christophe JAILLET]

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
v2: have the subject and updated driver match
---
 drivers/dma/qcom/hidma.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
index 65d054bb11aa..51587cf8196b 100644
--- a/drivers/dma/qcom/hidma.c
+++ b/drivers/dma/qcom/hidma.c
@@ -838,9 +838,7 @@ static int hidma_probe(struct platform_device *pdev)
 	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 	if (rc) {
 		dev_warn(&pdev->dev, "unable to set coherent mask to 64");
-		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
-		if (rc)
-			goto dmafree;
+		goto dmafree;
 	}
 
 	dmadev->lldev = hidma_ll_init(dmadev->ddev.dev,
-- 
2.32.0

Re: [PATCH v2] dmaengine: qcom_hidma: Remove useless DMA-32 fallback configuration

[Sinan Kaya]

On 1/15/2022 2:35 AM, Christophe JAILLET wrote:
> As stated in [1], dma_set_mask() with a 64-bit mask never fails if
> dev->dma_mask is non-NULL.
> So, if it fails, the 32 bits case will also fail for the same reason.
> 
> Simplify code and remove some dead code accordingly.
> 
> [1]: https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t
> 

Can we please document this?

Usual practice was to try allocating 64 bit DMA if possible and fallback
to 32 bits.

> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> v2: have the subject and updated driver match
> ---
>   drivers/dma/qcom/hidma.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
> index 65d054bb11aa..51587cf8196b 100644
> --- a/drivers/dma/qcom/hidma.c
> +++ b/drivers/dma/qcom/hidma.c
> @@ -838,9 +838,7 @@ static int hidma_probe(struct platform_device *pdev)
>   	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>   	if (rc) {
>   		dev_warn(&pdev->dev, "unable to set coherent mask to 64");
> -		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> -		if (rc)
> -			goto dmafree;
> +		goto dmafree;
>   	}
>   
>   	dmadev->lldev = hidma_ll_init(dmadev->ddev.dev,

Re: [PATCH v2] dmaengine: qcom_hidma: Remove useless DMA-32 fallback configuration

[Christophe JAILLET]

Le 22/01/2022 à 19:05, Sinan Kaya a écrit :
> On 1/15/2022 2:35 AM, Christophe JAILLET wrote:
>> As stated in [1], dma_set_mask() with a 64-bit mask never fails if
>> dev->dma_mask is non-NULL.
>> So, if it fails, the 32 bits case will also fail for the same reason.
>>
>> Simplify code and remove some dead code accordingly.
>>
>> [1]: 
>> https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t
>>
> 
> Can we please document this?

Hi, the patch has been applied, but [1] is sometimes given as an 
explanation link.

CJ


[1]: 
https://lists.linuxfoundation.org/pipermail/iommu/2019-February/033674.html

> 
> Usual practice was to try allocating 64 bit DMA if possible and fallback
> to 32 bits.
> 
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>> v2: have the subject and updated driver match
>> ---
>>   drivers/dma/qcom/hidma.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
>> index 65d054bb11aa..51587cf8196b 100644
>> --- a/drivers/dma/qcom/hidma.c
>> +++ b/drivers/dma/qcom/hidma.c
>> @@ -838,9 +838,7 @@ static int hidma_probe(struct platform_device *pdev)
>>       rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>>       if (rc) {
>>           dev_warn(&pdev->dev, "unable to set coherent mask to 64");
>> -        rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
>> -        if (rc)
>> -            goto dmafree;
>> +        goto dmafree;
>>       }
>>       dmadev->lldev = hidma_ll_init(dmadev->ddev.dev,
> 
> 

Re: [PATCH v2] dmaengine: qcom_hidma: Remove useless DMA-32 fallback configuration

[Sinan Kaya]

On 3/19/2022 2:24 AM, Christophe JAILLET wrote:
> Le 22/01/2022 à 19:05, Sinan Kaya a écrit :
>> On 1/15/2022 2:35 AM, Christophe JAILLET wrote:
>>> As stated in [1], dma_set_mask() with a 64-bit mask never fails if
>>> dev->dma_mask is non-NULL.
>>> So, if it fails, the 32 bits case will also fail for the same reason.
>>>
>>> Simplify code and remove some dead code accordingly.
>>>
>>> [1]: 
>>> https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t
>>>
>>
>> Can we please document this?
> 
> Hi, the patch has been applied, but [1] is sometimes given as an 
> explanation link.
> 
> CJ
> 
> 
> [1]: 
> https://lists.linuxfoundation.org/pipermail/iommu/2019-February/033674.html

Sounds good, please carry my

Acked-By: Sinan Kaya <okaya@kernel.org>