RE: [PATCH v13 2/2] usb: typec: ucsi: add support for Cypress CCGx

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Hi Heikki,
> > > I still didn't understand why can't this just be taken care of in
> > > your I2C host driver? Why can't you just read 4 bytes at a time in
> > > your master_xfer hook until you have received as much as the message
> > > is asking, and only after that return?
> >
> > The I2C host hardware *cannot* read more than 4 bytes in any one xfer
> > according to the HW designers. Seriously broken crap, that piece of
> > hardware... (If that assertion from the HW designers is indeed true?
> > I suspect that it can be made to work, but the docs are closed and I
> > don't have HW to experiment with, so it remains a suspicion...)
> >
> > And the I2C host driver *cannot* be expected to know exactly how any
> > one client device needs to split xfers into many when the 4 byte limit
> > is getting in the way, and neither can the I2C core. Because I bet
> > there are devices where it's not even possible to split xfers while
> > keeping semantics equivalent...
> >
> > So, every client driver will need to adjust to this quirk if they are
> > to operate with this worthless I2C host (or others with similar
> > limitations, if there are any?). Fortunately, most client drivers
> > don't read in bulk. Unfortunately, many do...
> 
> OK, thanks for the explanation.
> 
> I think I'm repeating these questions. You guys already went through this, so
> sorry for the noise.
I will go ahead and post new set. Thank you Peter for explanation!

Thanks
Ajay
--nvpublic
> 
> 
> Thanks,
> 
> --
> heikki




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