Messages in this thread | | | Subject | Re: [PATCH v4 2/4] phy: qcom-qusb2: New driver for QUSB2 PHY on Qcom chips | From | Vivek Gautam <> | Date | Fri, 27 Jan 2017 11:54:40 +0530 |
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On 01/26/2017 11:45 PM, Bjorn Andersson wrote: > On Tue 24 Jan 01:19 PST 2017, Kishon Vijay Abraham I wrote: >> On Monday 23 January 2017 03:43 PM, Vivek Gautam wrote: >>> On Wed, Jan 18, 2017 at 11:33 PM, Bjorn Andersson > [..] >>> Yes, that's correct. The QMP and QUSB2 phy init sequences are a bunch >>> of static values for a particular IP version. These values hardly give a >>> meaningful data to put few phy bindings that could be referenced >>> to configure the phy further. >> Not really. You can have clearly defined phy binding to give meaningful data. >> Every driver doing the same configuration bloats the driver and these >> configuration values are just magic values which hardly can be reviewed by anyone. >>>> Further more moving this blob to devicetree will not allow us to treat >>>> the various QMP configurations as one HW block, as there are other >>>> differences as well. >>>> >>>> Like many other drivers it's possible to create a generic version that >>>> has every bit of logic driven by configuration from devicetree, but like >>>> most of those cases this is not the way we split things. >>>> >>>> And this has the side effect of keeping the dts files human readable, >>>> human understandable and human maintainable. >> right. That's why I recommend having clearly defined bindings. >> phy,tx-<param1> = <val, offset, mask> >> phy,tx-<param2> = <val, offset, mask> >> phy,tx-<param3> = <val, offset, mask> > There's no doubt that this table needs to be encoded somewhere, so the > question is should we hard code this in a C file or in a DTSI file. > > Skimming through [1] I see examples of things that differs based on how > the specific component is integrated in a SoC or on a particular board - > properties that are relevant to a "system integrator". > > As far as I can tell this blob will, if ever, only be changed by a > driver developer and as such it's not carry information about how this > component relates to the rest of the system and should as such not be > part of the device tree. > > > If there are properties of the hardware that is affected by how the > component is integrated in the system I really would like for those to > be exposed as human-readable properties that I can understand and alter > without deep knowledge about the register map of the hardware block.
I am reaching out to our internal teams to get more information on different possible phy configurations, based on which the registers values are decided. This is something that i tried to understand in the past as well, but couldn't grab much information that time. Will come back with relevant information on this.
Regards Vivek
>> [1] -> https://www.linuxplumbersconf.org/2016/ocw/proposals/4047 > Regards, > Bjorn > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
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