[PATCH] at91: sam9x5 dt: add usart dma definitions to dt

[Jiří Prchal]

Hi,

Dne 10.10.2014 v 10:39 Nicolas Ferre napsal(a):
> On 10/10/2014 10:12, Ludovic Desroches :
>> Hi,
>>
>> On Fri, Oct 10, 2014 at 08:35:56AM +0200, Jiri Prchal wrote:
>>> This patch adds usart dma definitions to both dtsi for sam9x5 chips. Without
>>> usage of dma it's unable to catch all bytes on usart receiver.
>
> At which speed, with which kind of load on the CPU?
At 115200b/s, load aprox. 10% at 400MHz.
>
>> Adding DMA configuration is a good idea. But I think we will have an
>> issue because we have too many requested channels for DMA0.
I discovered that dma has only 8 channels for 15 peripherals right now.
And it makes big problem to me, I need at least 9ch on dma0 since on dma1 need only 6.
>>
>> Adding usart0, 9 dma channels will be requested. So a choice has to be
>> done. On DMA0 we have:
>> - 2 channels for SSC,
>> - 1 channel for MMC,
>> - 2 channels for I2C0,
>> - 2 channels for SPI0,
>> - 2 channels for USART0.
>
> Yes, so maybe disable the DMA for SPI0. But the decision is pretty
> related to the use of the board. So I would not change things...
No, SPI0 need too.
>
>> I have only mentioned enabled devices.
>
> Yes indeed,
>
> So maybe we can add the "dmas" properties in the files mentioned by
> Jiri, but not enable them like you did Ludovic in this patch:
>
> d24cd78399a3625a69887c8124638260c1c37a2b (ARM: at91: sama5d3: add usart
> dma configurations)
>
> Bye,
But is it possible to enable/disable dma at runtime from userspace?
>
>
>>> Signed-off-by: Jiri Prchal <jiri.prchal at aksignal.cz>
>>> ---
>>>   arch/arm/boot/dts/at91sam9x5.dtsi        | 20 ++++++++++++++++++++
>>>   arch/arm/boot/dts/at91sam9x5_usart3.dtsi |  5 +++++
>>>   2 files changed, 25 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/at91sam9x5.dtsi b/arch/arm/boot/dts/at91sam9x5.dtsi
>>> index 726274f..f9acf6d 100644
>>> --- a/arch/arm/boot/dts/at91sam9x5.dtsi
>>> +++ b/arch/arm/boot/dts/at91sam9x5.dtsi
>>> @@ -860,6 +860,11 @@
>>>   				interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>;
>>>   				pinctrl-names = "default";
>>>   				pinctrl-0 = <&pinctrl_dbgu>;
>>> +				atmel,use-dma-tx;
>>> +				atmel,use-dma-rx;
>>> +				dmas = <&dma1 1 AT91_DMA_CFG_PER_ID(8)>,
>>> +				       <&dma1 1 (AT91_DMA_CFG_PER_ID(9) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>>> +				dma-names = "tx", "rx";
>>>   				clocks = <&mck>;
>>>   				clock-names = "usart";
>>>   				status = "disabled";
>>> @@ -871,6 +876,11 @@
>>>   				interrupts = <5 IRQ_TYPE_LEVEL_HIGH 5>;
>>>   				pinctrl-names = "default";
>>>   				pinctrl-0 = <&pinctrl_usart0>;
>>> +				atmel,use-dma-rx;
>>> +				atmel,use-dma-tx;
>>> +				dmas = <&dma0 1 AT91_DMA_CFG_PER_ID(3)>,
>>> +				       <&dma0 1 (AT91_DMA_CFG_PER_ID(4) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>>> +				dma-names = "tx", "rx";
>>>   				clocks = <&usart0_clk>;
>>>   				clock-names = "usart";
>>>   				status = "disabled";
>>> @@ -882,6 +892,11 @@
>>>   				interrupts = <6 IRQ_TYPE_LEVEL_HIGH 5>;
>>>   				pinctrl-names = "default";
>>>   				pinctrl-0 = <&pinctrl_usart1>;
>>> +				atmel,use-dma-rx;
>>> +				atmel,use-dma-tx;
>>> +				dmas = <&dma0 1 AT91_DMA_CFG_PER_ID(5)>,
>>> +				       <&dma0 1 (AT91_DMA_CFG_PER_ID(6) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>>> +				dma-names = "tx", "rx";
>>>   				clocks = <&usart1_clk>;
>>>   				clock-names = "usart";
>>>   				status = "disabled";
>>> @@ -893,6 +908,11 @@
>>>   				interrupts = <7 IRQ_TYPE_LEVEL_HIGH 5>;
>>>   				pinctrl-names = "default";
>>>   				pinctrl-0 = <&pinctrl_usart2>;
>>> +				atmel,use-dma-rx;
>>> +				atmel,use-dma-tx;
>>> +				dmas = <&dma1 1 AT91_DMA_CFG_PER_ID(12)>,
>>> +				       <&dma1 1 (AT91_DMA_CFG_PER_ID(13) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>>> +				dma-names = "tx", "rx";
>>>   				clocks = <&usart2_clk>;
>>>   				clock-names = "usart";
>>>   				status = "disabled";
>>> diff --git a/arch/arm/boot/dts/at91sam9x5_usart3.dtsi b/arch/arm/boot/dts/at91sam9x5_usart3.dtsi
>>> index 140217a5..731da0e 100644
>>> --- a/arch/arm/boot/dts/at91sam9x5_usart3.dtsi
>>> +++ b/arch/arm/boot/dts/at91sam9x5_usart3.dtsi
>>> @@ -57,6 +57,11 @@
>>>   				interrupts = <8 IRQ_TYPE_LEVEL_HIGH 5>;
>>>   				pinctrl-names = "default";
>>>   				pinctrl-0 = <&pinctrl_usart3>;
>>> +				atmel,use-dma-rx;
>>> +				atmel,use-dma-tx;
>>> +				dmas = <&dma1 1 AT91_DMA_CFG_PER_ID(14)>,
>>> +				       <&dma1 1 (AT91_DMA_CFG_PER_ID(15) | AT91_DMA_CFG_FIFOCFG_ASAP)>;
>>> +				dma-names = "tx", "rx";
>>>   				clocks = <&usart3_clk>;
>>>   				clock-names = "usart";
>>>   				status = "disabled";
>>> --
>>> 1.9.1
>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>>
>
>