Messages in this thread | | | Date | Fri, 1 Oct 2021 13:37:50 +0530 | From | Pratyush Yadav <> | Subject | Re: [PATCH v5 2/6] phy: cdns-dphy: Add Rx support |
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On 01/10/21 11:53AM, Vinod Koul wrote: > Hi Pratyush, > > On 17-09-21, 22:58, Pratyush Yadav wrote: > > +Rob > > > > On 16/09/21 12:22PM, Paul Kocialkowski wrote: > > > Hi, > > > > > > On Fri 03 Sep 21, 00:25, Pratyush Yadav wrote: > > > > The Cadence DPHY can be used to receive image data over the CSI-2 > > > > protocol. Add support for Rx mode. The programming sequence differs from > > > > the Tx mode so it is added as a separate set of hooks to isolate the two > > > > paths. The mode in which the DPHY has to be used is selected based on > > > > the compatible. > > > > > > I just realized that I didn't follow-up on a previous revision on the debate > > > about using the phy sub-mode to distinguish between rx/tx. > > > > > > I see that you've been using a dedicated compatible, but I'm not sure this is a > > > good fit either. My understanding is that the compatible should describe a group > > > of register-compatible revisions of a hardware component, not how the hardware > > > is used specifically. I guess the distinction between rx/tx falls under > > > the latter rather than the former. > > > > I am not sure if that is the case. For example, we use "ti,am654-ospi" > > for Cadence Quadspi controller. The default compatible, "cdns,qspi-nor", > > only supports Quad SPI (4 lines). The "ti,am654-ospi" compatible also > > supports Octal SPI (8 lines). > > Those are hardware defaults right? > > > In addition, I feel like the Rx DPHY is almost a different type of > > device from a Tx DPHY. The programming sequence is completely different, > > Is that due to direction or something else..?
Yes, it is due to direction. Different settings need to be applied for Rx mode.
> > > the clocks required are different, etc. So I think using a different > > compatible for Rx mode makes sense. > > Is the underlaying IP not capable of both TX and RX and in the specific > situations you are using it as TX and RX.
Any instance of the underlying IP can only either be TX or RX, it can't do both.
> > I am okay that default being TX but you can use Paul's approach of > direction with this to make it better proposal
Ok, will update this patch then.
-- Regards, Pratyush Yadav Texas Instruments Inc.
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