linux-kernel - Re: [PATCH 3/3] dma: jz4780: Add support for the MDMA in the JZ4760(B)

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Message-Id: <ML4YWQ.2MOPKABT5JGC1@crapouillou.net>
Date:   Wed, 28 Jul 2021 09:22:34 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>, dmaengine@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, list@...ndingux.net
Subject: Re: [PATCH 3/3] dma: jz4780: Add support for the MDMA in the
 JZ4760(B)

Hi Vinod,

Le mer., juil. 28 2021 at 12:46:20 +0530, Vinod Koul <vkoul@...nel.org> 
a écrit :
> On 18-07-21, 13:20, Paul Cercueil wrote:
>>  The JZ4760 and JZ4760B SoCs have two regular DMA controllers with 6
>>  channels each. They also have an extra DMA controller named MDMA
>>  with only 2 channels, that only supports memcpy operations.
> 
> It is dmaengine not dma:
> 
>> 
>>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  ---
>>   drivers/dma/dma-jz4780.c | 22 ++++++++++++++++++++--
>>   1 file changed, 20 insertions(+), 2 deletions(-)
>> 
>>  diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
>>  index d71bc7235959..eed505e3cce2 100644
>>  --- a/drivers/dma/dma-jz4780.c
>>  +++ b/drivers/dma/dma-jz4780.c
>>  @@ -93,6 +93,7 @@
>>   #define JZ_SOC_DATA_PER_CHAN_PM		BIT(2)
>>   #define JZ_SOC_DATA_NO_DCKES_DCKEC	BIT(3)
>>   #define JZ_SOC_DATA_BREAK_LINKS		BIT(4)
>>  +#define JZ_SOC_DATA_ONLY_MEMCPY		BIT(5)
> 
> Why -ve logic? Looks like MEMCPY is eveywhere and only peripheral is 
> not
> there at few SoC, so use JZ_SOC_DATA_PERIPHERAL

That means touching every other jz4780_dma_soc_data structure in a 
patch that's focused on one SoC. That means a messy patch, and I don't 
like that.

Negative logic is a problem if it makes it harder to understand, I 
don't think it's the case here. Besides, we already have 
JZ_SOC_DATA_NO_DCKES_DCKEC.

Cheers,
-Paul

>> 
>>   /**
>>    * struct jz4780_dma_hwdesc - descriptor structure read by the DMA 
>> controller.
>>  @@ -896,8 +897,10 @@ static int jz4780_dma_probe(struct 
>> platform_device *pdev)
>>   	dd = &jzdma->dma_device;
>> 
>>   	dma_cap_set(DMA_MEMCPY, dd->cap_mask);
>>  -	dma_cap_set(DMA_SLAVE, dd->cap_mask);
>>  -	dma_cap_set(DMA_CYCLIC, dd->cap_mask);
>>  +	if (!(soc_data->flags & JZ_SOC_DATA_ONLY_MEMCPY)) {
>>  +		dma_cap_set(DMA_SLAVE, dd->cap_mask);
>>  +		dma_cap_set(DMA_CYCLIC, dd->cap_mask);
>>  +	}
> 
> and set this if JZ_SOC_DATA_PERIPHERAL is set?
> 
>> 
>>   	dd->dev = dev;
>>   	dd->copy_align = DMAENGINE_ALIGN_4_BYTES;
>>  @@ -1018,12 +1021,25 @@ static const struct jz4780_dma_soc_data 
>> jz4760_dma_soc_data = {
>>   	.flags = JZ_SOC_DATA_PER_CHAN_PM | JZ_SOC_DATA_NO_DCKES_DCKEC,
>>   };
>> 
>>  +static const struct jz4780_dma_soc_data jz4760_mdma_soc_data = {
>>  +	.nb_channels = 2,
>>  +	.transfer_ord_max = 6,
>>  +	.flags = JZ_SOC_DATA_PER_CHAN_PM | JZ_SOC_DATA_NO_DCKES_DCKEC |
>>  +		 JZ_SOC_DATA_ONLY_MEMCPY,
>>  +};
>>  +
>>   static const struct jz4780_dma_soc_data jz4760b_dma_soc_data = {
>>   	.nb_channels = 5,
>>   	.transfer_ord_max = 6,
>>   	.flags = JZ_SOC_DATA_PER_CHAN_PM,
>>   };
>> 
>>  +static const struct jz4780_dma_soc_data jz4760b_mdma_soc_data = {
>>  +	.nb_channels = 2,
>>  +	.transfer_ord_max = 6,
>>  +	.flags = JZ_SOC_DATA_PER_CHAN_PM | JZ_SOC_DATA_ONLY_MEMCPY,
>>  +};
>>  +
>>   static const struct jz4780_dma_soc_data jz4770_dma_soc_data = {
>>   	.nb_channels = 6,
>>   	.transfer_ord_max = 6,
>>  @@ -1052,7 +1068,9 @@ static const struct of_device_id 
>> jz4780_dma_dt_match[] = {
>>   	{ .compatible = "ingenic,jz4740-dma", .data = 
>> &jz4740_dma_soc_data },
>>   	{ .compatible = "ingenic,jz4725b-dma", .data = 
>> &jz4725b_dma_soc_data },
>>   	{ .compatible = "ingenic,jz4760-dma", .data = 
>> &jz4760_dma_soc_data },
>>  +	{ .compatible = "ingenic,jz4760-mdma", .data = 
>> &jz4760_mdma_soc_data },
>>   	{ .compatible = "ingenic,jz4760b-dma", .data = 
>> &jz4760b_dma_soc_data },
>>  +	{ .compatible = "ingenic,jz4760b-mdma", .data = 
>> &jz4760b_mdma_soc_data },
>>   	{ .compatible = "ingenic,jz4770-dma", .data = 
>> &jz4770_dma_soc_data },
>>   	{ .compatible = "ingenic,jz4780-dma", .data = 
>> &jz4780_dma_soc_data },
>>   	{ .compatible = "ingenic,x1000-dma", .data = &x1000_dma_soc_data 
>> },
>>  --
>>  2.30.2
> 
> --
> ~Vinod