On 28-09-18, 15:01, Pierre-Yves MORDRET wrote: > From: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx> > > This patch adds dma bindings to support DMA/MDMA chaining transfer. > 1 bit is to manage both DMA FIFO Threshold > 1 bit is to manage DMA/MDMA Chaining features. > 2 bits are used to specify SDRAM size to use for DMA/MDMA chaining. Please do mention which specific bits? > The size in bytes of a certain order is given by the formula: > (2 ^ order) * PAGE_SIZE. > The order is given by those 2 bits. > For cyclic, whether chaining is chosen, any value above 1 can be set : > SRAM buffer size will rely on period size and not on this DT value. > > Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@xxxxxx> > --- > Version history: > v3: > v2: > * rework content > v1: > * Initial > --- > --- > .../devicetree/bindings/dma/stm32-dma.txt | 27 +++++++++++++++++++++- > 1 file changed, 26 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/dma/stm32-dma.txt b/Documentation/devicetree/bindings/dma/stm32-dma.txt > index c5f5190..2bac8c7 100644 > --- a/Documentation/devicetree/bindings/dma/stm32-dma.txt > +++ b/Documentation/devicetree/bindings/dma/stm32-dma.txt > @@ -17,6 +17,12 @@ Optional properties: > - resets: Reference to a reset controller asserting the DMA controller > - st,mem2mem: boolean; if defined, it indicates that the controller supports > memory-to-memory transfer > +- dmas: A list of eight dma specifiers, one for each entry in dma-names. > + Refer to stm32-mdma.txt for more details. > +- dma-names: should contain "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6" and > + "ch7" and represents each STM32 DMA channel connected to a STM32 MDMA one. > +- memory-region : phandle to a node describing memory to be used for > + M2M intermediate transfer between DMA and MDMA. > > Example: > > @@ -36,6 +42,16 @@ Example: > st,mem2mem; > resets = <&rcc 150>; > dma-requests = <8>; > + dmas = <&mdma1 8 0x10 0x1200000a 0x40026408 0x00000020 1>, > + <&mdma1 9 0x10 0x1200000a 0x40026408 0x00000800 1>, > + <&mdma1 10 0x10 0x1200000a 0x40026408 0x00200000 1>, > + <&mdma1 11 0x10 0x1200000a 0x40026408 0x08000000 1>, > + <&mdma1 12 0x10 0x1200000a 0x4002640C 0x00000020 1>, > + <&mdma1 13 0x10 0x1200000a 0x4002640C 0x00000800 1>, > + <&mdma1 14 0x10 0x1200000a 0x4002640C 0x00200000 1>, > + <&mdma1 15 0x10 0x1200000a 0x4002640C 0x08000000 1>; > + dma-names = "ch0", "ch1", "ch2", "ch3", "ch4", "ch5", "ch6", "ch7"; > + memory-region = <&sram_dmapool>; > }; > > * DMA client > @@ -68,7 +84,16 @@ channel: a phandle to the DMA controller plus the following four integer cells: > 0x1: 1/2 full FIFO > 0x2: 3/4 full FIFO > 0x3: full FIFO > - > + -bit 2: Intermediate M2M transfer from/to DDR to/from SRAM throughout MDMA > + 0: MDMA not used to generate an intermediate M2M transfer > + 1: MDMA used to generate an intermediate M2M transfer. > + -bit 3-4: indicated SRAM Buffer size in (2^order)*PAGE_SIZE. > + PAGE_SIZE is given by Linux at 4KiB: include/asm-generic/page.h. > + Order is given by those 2 bits starting at 0. > + Valid only whether Intermediate M2M transfer is set. why do we need this as a property? > + For cyclic, whether Intermediate M2M transfer is chosen, any value can > + be set: SRAM buffer size will rely on period size and not on this DT > + value. > > Example: > > -- > 2.7.4 -- ~Vinod
