Re: [PATCH 0/3] Implement role-switch notifications from dwc3-drd to dwc3-qcom

[Felipe Balbi <balbi@kernel.org>]

Hi,

Bjorn Andersson <bjorn.andersson@linaro.org> writes:
> On Wed 25 Aug 10:59 PDT 2021, Bryan O'Donoghue wrote:
>
>> On 25/08/2021 16:53, Bjorn Andersson wrote:
>> > But in the case of Type-C altmode several of our boards have either an
>> > external gpio-based SBU-pin-swapper or some redriver on I2C with this
>> > functionality, so we need a way to tell both the PHY and this external
>> > contraption about the orientation.
>> 
>> Its a very similar problem to orientation switch
>> 
>> As an example
>> 
>> - redriver may need to fix up signal integrity for
>>   lane switching
>> 
>> - PHY needs to toggle lanes from one IP block to another
>> 
>
> Right, conceptually the problem is similar, but IMHO there's a big
> difference in that the redriver and PHY are two physically separate
> entities - on different buses. The dwc3 glue and core represent the same
> piece of hardware.

no they don't. The glue is a real piece of HW that adapts the "generic"
synopsys IP to a given SoC. OMAP, for example, was adapting Synopsys'
proprietary interface to the Sonics interconnect, while some others may
adapt it to AXI or PCI or whatever.

They are different HW blocks, the glue (in many cases) has its own IRQ,
its own address space, its own register file, and so on. Granted, the
glue also serves as an access port from CPU to the synopsys core, but
that's handled by `ranges' DT property.

-- 
balbi