On 10/22/2013 06:25 AM, Matt Porter wrote: > On Tue, Oct 22, 2013 at 12:48:29PM +0200, Matthijs Kooijman wrote: >> Hi Kishon, >> >> On Mon, Oct 21, 2013 at 02:57:26PM +0530, Kishon Vijay Abraham I wrote: >>> I think it makes sense to keep the data width property in the dwc2 node itself. >>> I mean it describes how the dwc2 IP is configured in that particular SoC (given >>> that it can be either <8> or <16>). >> If I'm reading the RT3052 datasheet correctly (GHWCFG4 register), the IP >> can be configured for 8, 16 or 8 _and_ 16. In the latter case, the "8 >> and 16 supported" would make sense as a property of dwc2 (though this >> value should be autodetectable through GHWCFG4), while the actual 8 or >> 16 supported by the PHY would make sense as property of a phy. > > There would be no value in adding a property for an already detectable > value to dwc2's binding. To be honest, it's pretty much useless > information due to the existence of the "8 and 16" option. > >> Note sure if this is really useful in practice as well, or if just >> setting the actual width to use on dwc2 makes more sense... > > The GHWCFG4 information itself is not useful in practice, as described > in the original thread: https://lkml.org/lkml/2013/10/10/477 > > It's certainly useful in practice to have this width property in either > the dwc2 or the phy binding. One can make a case for either. As I > mentioned in the original post, if we put it in the phy binding we'll be > updating the generic phy binding. We'll then need an api added into the > generic phy framework to fetch the width of a phy. > > Both cases are doable and trivial, we just need the canonical decision > from a DT maintainer as to where the property belongs. Given that they > are in ARM ksummit, I'm not expecting to hear anything right this > moment. :) The host can support both, so it is not a property of the host and is a property of the phy. It is no different than what mode a SPI slave requires or whether an i2c slave supports 8 or 10-bit addressing. Those examples are all 1 to many rather than 1 to 1 where it doesn't really matter, but the same logic applies. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
