On Wed, Oct 18, 2017 at 1:25 AM, Miquel RAYNAL <miquel.raynal@xxxxxxxxxxxxxxxxxx> wrote: > Hi Rob, > > On Tue, 17 Oct 2017 17:00:22 -0500 > Rob Herring <robh@xxxxxxxxxx> wrote: > >> On Fri, Oct 13, 2017 at 11:01:45AM +0200, Miquel Raynal wrote: >> > Update the Device Tree binding documentation for the Marvell EBU >> > UART, in order to allow describing the extended UART IP block, in >> > addition to the already supported standard UART IP. This requires >> > adding a new compatible string, the introduction of a clocks >> > property, and extensions to the interrupts property. >> > >> > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx> >> > Reviewed-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> >> > --- >> > .../devicetree/bindings/serial/mvebu-uart.txt | 49 >> > +++++++++++++++++++--- 1 file changed, 44 insertions(+), 5 >> > deletions(-) >> > >> > diff --git >> > a/Documentation/devicetree/bindings/serial/mvebu-uart.txt >> > b/Documentation/devicetree/bindings/serial/mvebu-uart.txt index >> > d37fabe17bd1..3df3a3fab4bb 100644 --- >> > a/Documentation/devicetree/bindings/serial/mvebu-uart.txt +++ >> > b/Documentation/devicetree/bindings/serial/mvebu-uart.txt @@ -1,13 >> > +1,52 @@ -* Marvell UART : Non standard UART used in some of >> > Marvell EBU SoCs (e.g., Armada-3700) +* Marvell UART : Non standard >> > UART used in some of Marvell EBU SoCs >> > + e.g., Armada-3700. >> > >> > Required properties: >> > -- compatible: "marvell,armada-3700-uart" >> > +- compatible: >> > + - "marvell,armada-3700-uart" for the standard variant of the >> > UART >> > + (32 bytes FIFO, no DMA, level interrupts, 8-bit access to the >> > + FIFO, baudrate limited to 230400). >> > + - "marvell,armada-3700-uart-ext" for the extended variant of >> > the >> > + UART (128 bytes FIFO, DMA, front interrupts, 8-bit or 32-bit >> > + accesses to the FIFO, baudrate unlimited by the dividers). >> >> What do you call the next extended version? >> marvell,armada-3700-uart-ext-ext? > > I don't know what you mean by "next extended version"? IP evolves on new chips with new features. Just trying to understand how you are >> This is different versions of UART on the same chip? > > Today in mainline there is support for the A3700 UART IP. > This series add support for another IP, based on the A3700, but with > extended features (explaining the -ext suffix). > > Can you precise what is bothering you? Is this different versions of UART IP on 1 chip or a new version of the UART IP on a new SoC? The latter should be a new compatible with the new SoC. The former case does happen some, but is not common. I'm just trying to understand which applies here. >> > - reg: offset and length of the register set for the device. >> > -- interrupts: device interrupt >> > +- clocks: UART reference clock used to derive the baudrate (only >> > + mandatory with "marvell,armada-3700-uart-ext" compatible). >> >> How is this optional? The freq is fixed if not present? If so, what >> frequency? > > The "clocks" property should not be optional at all but that is how the > bindings were handled before this series, so I can't tell now that > this property is mandatory as it would break compatibility with older > versions of the driver. Okay. I think it should be mandatory with a note how missing property is handled. > When no clock is provided, the frequency is fixed by the bootloader > and cannot be changed. There is no standard frequency for it but the > one chosen by the bootloader often is 115200 as the UART is usually > used as the serial console. > > Because the bootloader does only initialize the UART in use for the > serial console, the clock is mandatory when using another port or it > will not work at all. -- 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
