[PATCH v2 1/2] serial: mxc: enable the RX pipeline

[Tom Rini]

On Tue, Sep 06, 2022 at 09:04:05AM +0800, Peng Fan wrote:
> 
> 
> On 9/5/2022 5:58 PM, Johannes Schneider wrote:
> > on imx8(mm) the RXDMUXSEL needs to be set for data going over the wire
> > (as observable on a connected 'scope) to actually make it into the
> > RXFIFO
> > 
> > the reference manual is not overly clear about this, and only
> > mentiones that "UCR3_RXDMUXSEL should always be set." - and since the
> > CR3 register reverts to its reset values after setting the baudrate,
> > setting this bit is done during '_mxc_serial_setbgr'
> > 
> > Signed-off-by: Johannes Schneider <johannes.schneider at leica-geosystems.com>
> > 
> > ---
> > 
> > (no changes since v1)
> > 
> >   drivers/serial/serial_mxc.c | 11 +++++++++++
> >   1 file changed, 11 insertions(+)
> > 
> > diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
> > index 70a0e5e919..5f283cc635 100644
> > --- a/drivers/serial/serial_mxc.c
> > +++ b/drivers/serial/serial_mxc.c
> > @@ -61,6 +61,11 @@
> >   #define UCR3_AWAKEN	(1<<4)  /* Async wake interrupt enable */
> >   #define UCR3_REF25	(1<<3)  /* Ref freq 25 MHz */
> >   #define UCR3_REF30	(1<<2)  /* Ref Freq 30 MHz */
> > +
> > +//imx8 names these bitsfields instead:
> > +#define UCR3_DTRDEN	BIT(3)  /* bit not used in this chip */
> > +#define UCR3_RXDMUXSEL	BIT(2)  /* RXD muxed input selected; 'should always be set' */
> > +
> >   #define UCR3_INVT	(1<<1)  /* Inverted Infrared transmission */
> >   #define UCR3_BPEN	(1<<0)  /* Preset registers enable */
> >   #define UCR4_CTSTL_32	(32<<10) /* CTS trigger level (32 chars) */
> > @@ -176,6 +181,12 @@ static void _mxc_serial_setbrg(struct mxc_uart *base, unsigned long clk,
> >   	writel(UCR2_WS | UCR2_IRTS | UCR2_RXEN | UCR2_TXEN | UCR2_SRST,
> >   	       &base->cr2);
> > +
> > +	// setting the baudrate triggers a reset, returning cr3 to its
> > +	// reset value but UCR3_RXDMUXSEL "should always be set."
> > +	// according to the imx8 reference-manual
> > +	writel(readl(&base->cr3) | UCR3_RXDMUXSEL, &base->cr3);
> 
> Please fix comment format.

We allow '//' style comments, just like the linux kernel does these
days. There should be a space before the "imx8" in the first hunk here.

-- 
Tom
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 659 bytes
Desc: not available
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20220905/ad06f117/attachment.sig>