Le 11/06/2015 18:20, Cyrille Pitchen a écrit : > This patch adds a new DT property, "atmel,fifo-size", to enable and set > the maximum number of data the RX and TX FIFOs can store on FIFO capable > USARTs. > > Please be aware that the VERSION register can not be used to guess the > size of FIFOs. Indeed, for a given hardware version, the USARTs can be > integrated on Atmel SoCs with different FIFO sizes. Also the > "atmel,fifo-size" property is optional as older USARTs don't embed FIFO at > all. > > Besides, the FIFO size can not be read or guessed from other registers: > When designing the FIFO feature, no dedicated registers were added to > store this size. Unsed spaces in the I/O register range are limited and > better reserved for future usages. Instead, the FIFO size of each > peripheral is documented in the programmer datasheet. > > Finally, on a given SoC, there can be several instances of USART with > different FIFO sizes. This explain why we'd rather use a dedicated DT > property than use the "compatible" property. > > Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx> Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> > --- > Documentation/devicetree/bindings/serial/atmel-usart.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/devicetree/bindings/serial/atmel-usart.txt b/Documentation/devicetree/bindings/serial/atmel-usart.txt > index 90787aa..e6e6142 100644 > --- a/Documentation/devicetree/bindings/serial/atmel-usart.txt > +++ b/Documentation/devicetree/bindings/serial/atmel-usart.txt > @@ -22,6 +22,8 @@ Optional properties: > memory peripheral interface and USART DMA channel ID, FIFO configuration. > Refer to dma.txt and atmel-dma.txt for details. > - dma-names: "rx" for RX channel, "tx" for TX channel. > +- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO > + capable USARTs. > > <chip> compatible description: > - at91rm9200: legacy USART support > @@ -57,4 +59,5 @@ Example: > dmas = <&dma0 2 0x3>, > <&dma0 2 0x204>; > dma-names = "tx", "rx"; > + atmel,fifo-size = <32>; > }; > -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
