[PATCH v2] i.MX51 iomux: Fixes MX51_PAD_UART2_TXD__UART2_TXD declaration

[Richard Zhao]

On Fri, Feb 11, 2011 at 02:58:02PM +0100, Lothar Waßmann wrote:
> Hi,
> 
> Richard Zhao writes:
> > On Fri, Feb 11, 2011 at 02:05:21PM +0100, Lothar Waßmann wrote:
> > > Hi,
> > > 
> > > Richard Zhao writes:
> > > > Hi Julien,
> > > > 
> > > > #define _MX51_PAD_USBH1_DATA2__UART2_TXD	IOMUX_PAD(0x690, 0x290, 1, 0x09ec, 5, 0)
> > > > 
> > > > Will you change the above line too?
> > > > 
> > > Seems like a general copy/paste error in the i.MX51 Ref Manual.
> > > For all pads that can have an UART RXD or TXD function the manual
> > > states that the UART*_IPP_UART_RXD_MUX_SELECT_INPUT register must be
> > > configured, while this is obviously only sensible for the RXD
> > > function.
> > Yes, it's for RXD. RXD can also select input from TXD.
> > 
> The RXD function can be routed to the TXD pads via
> RXD_MUX_SELECT_INPUT, but IMO setting the INPUT_MUX for an OUTPUT
> function (TXD) is nonsense.
> 
> E.g.:
> |Table A-1271. Register: IOMUXC_UART2_IPP_UART_RXD_MUX_SELECT_INPUT
> |
> |010: Selecting Pad: UART2_RXD for Mode: ALT0.
> |011: Selecting Pad: UART2_TXD for Mode: ALT0.
> so, the input path for the RXD function can be routed to either the
> UART2_RXD or UART2_TXD pad.
Right. I double checked with IC guys. 011 means UART2_TXD/RXD swapped. When
changing mode of DCE/DTE, TXD/RXD and RTS/CTS may need swapped. Using this
setting, you don't need to swap the physical wires.

Thanks
Richard
> 
> |Table A-286. Register IOMUXC_SW_MUX_CTL_PAD_UART2_RXD Bits Description
> |000: Select mux mode: ALT0 mux port: RXD_MUX of instance: uart2.
> |NOTE: Pad UART2_RXD is involved in Daisy Chain.
> |- Config Register IOMUXC_UART2_IPP_UART_RXD_MUX_SELECT_INPUT for mode
> |ALT0.
> This is OK. RXD_MUX is an input whose source is defined by the
> RXD_MUX_SELECT_INPUT register.
> 
> But:
> |Table A-288. Register IOMUXC_SW_MUX_CTL_PAD_UART2_TXD Bits Description
> |000: Select mux mode: ALT0 mux port: TXD_MUX of instance: uart2.
> |
> |NOTE: Pad UART2_TXD is involved in Daisy Chain.
> |- Config Register IOMUXC_UART2_IPP_UART_RXD_MUX_SELECT_INPUT for mode
> |ALT0.
> IMO does not make any sense. TXD_MUX is an OUTPUT function.
> How can the INPUT MUX route an OUTPUT PAD?
> 
> Also, the table Table 4-3. i.MX51 Daisy Chain Settings only mentions
> the uart_rxd_mux pins, but not uart_txd_mux.
> 
> 
> Lothar Waßmann
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