Re: [PATCH 4/4] staging: dwc2: load parameters from the devicetree

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Hi Paul,

> These are the core parameters that I think are needed right now:
> 
> 	dma_enable
> 	dma_desc_enable
> 	host_rx_fifo_size
> 	host_nperio_tx_fifo_size
> 	host_perio_tx_fifo_size
> 	max_transfer_size
> 	max_packet_count
> 	host_channels
> 
> 	phy_type
> 	phy_utmi_width
> 	phy_ulpi_ddr
> 	phy_ulpi_ext_vbus
> 	i2c_enable
> 	ulpi_fs_ls
> 	host_support_fs_ls_low_power
> 	host_ls_low_power_phy_clk
> 
> The last 8 are related to the Phy. I wonder if they should be in a
> separate Phy dt file?

Looking at the dwc3 driver, it can have a "usb-phy" phandle property in
its dt node that points to a different phy node in the dt, possibly with
a different driver. However, all of the glue drivers default the phy to
a nop_usb_xceiv phy driver, which is basically a noop driver AFAICS.

I'm not sure if the dwc2 hardware could ever be connected to an external
PHY that actually needs a driver? Or does the dwc2 core do all the
talking to the PHY and are these parameters just to tell the core how to
talk to the PHY?

As you might gather from the above, I'm not really in the loop about how
the hardware works here, so I don't think I'm qualified to decide on the
best approach here... Perhaps I should adapt my patch to just the
non-phy related parameters and we can do the phy-stuff later when it is
clear how they should work?

Gr.

Matthijs
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