On 09/23/2013 11:06 PM, Stephen Warren wrote: > On 09/18/2013 04:01 AM, Maxime COQUELIN wrote: >> This patch adds support to SSC (Synchronous Serial Controller) >> I2C driver. This IP also supports SPI protocol, but this is not >> the aim of this driver. >> >> This IP is embedded in all ST SoCs for Set-top box platorms, and >> supports I2C Standard and Fast modes. >> diff --git a/Documentation/devicetree/bindings/i2c/i2c-st.txt b/Documentation/devicetree/bindings/i2c/i2c-st.txt >> +I2C for ST platforms > If the HW block supports both I2C and SPI, the DT binding ought to > support that too. It's be best to create a single DT binding that > represents the IP block, and include a property that indicates whether > the device should operate in I2C or SPI mode. > > I suppose you could reasonably define different compatible values for > those two cases. However, the binding should be titled something more > like "ST SSC binding, for I2C mode operation" and "ST SSC binding, for > SPI mode operation", rather than "I2C for ST platforms", since the HW > includes an SSC block, not an I2C block. You are right Stephen. I will rename the title and change the compatible value as per your recommendation. >> +Required properties : >> +- compatible : Must be "st,comms-i2c" >> +- reg : Offset and length of the register set for the device >> +- interrupts : the interrupt number > It's an interrupt specifier, not an interrupt number. The format is > defined by the interrupt controller, not this binding. Ok. I will change to "the interrupt specifier". >> +- clocks : phandle to the I2C clock source > What about clock-names? It will be added in next revision. It will be named "ssc" >> +Recommended (non-standard) properties : > Usually you'd just say "Optional properties:", or perhaps "Recommended > properties:". I don't think adding "(non-standard)" serves any purpose. Ok. then I will remove all the "non-standard" occurences. >> +- clock-frequency : Desired I2C bus clock frequency in Hz. Otherwise >> + the default 100 kHz frequency will be used. As only Normal and Fast modes >> + are supported, possible values are 100000 and 400000. >> + >> +Optional (non-standard) properties: > Same here. > >> +- st,glitches : Enable timing glitch suppression support. > That property name doesn't really convey the "enables" that appears in > the property description to me... > >> +- st,glitch-clk : SCL line timinig glitch suppression value in ns. >> +- st,glitch-dat : SDA line timinig glitch suppression value in ns. > s/timinig/timing/ > >> +- st,hw-glitches : Enable filter glitch suppression support. >> +- st,hw-glitch-clk : SCL line filter glitch suppression value in us. >> +- st,hw-glitch-dat : SDA line filter glitch suppression value in us. > Those sound more like runtime configuration rather than HW description. > Can you rephrase the descriptions (and property names) more along the > lines of HW properties? Perhaps e.g.: > > st,needs-glitch-suppression: The board design needs timing glitch > suppression enabled to operate reliably. > > st,min-scl-pulse-width: The minimum valid SCL pulse width that is > allowed through the deglitch circuit. In units of ns. > > (I just made up those descriptions to give a feel for the flavor of > description that I expect. They likely need some adjustment to reflect > whatever they're actually intended to represent in HW). > > What is the difference between "glitch" and "hw-glitch"? "hw-glitch" is used to configure the anti-glitch filters. It suppresses the pulses with a width lower than x microseconds. "glitch" is is used to tune the I2C timing requirements, and has a nanosecond granularity. These values are added to default timing values. I'm not 100% sure, but it looks like the "samsung,i2c-sda-delay" in the i2c-s3c2410 driver. I agree the names and descriptions are not clear, and even misleading. I will come with a clearer implementation, as soon as I get clarification from HW team. Thanks for the review, Maxime -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
