[U-Boot] [PATCH] spi: cadence_qspi_apb: Ensure baudrate doesn't exceed max value

[Chin Liang See]

On Sun, 2016-08-07 at 16:05 +0200, Marek Vasut wrote:
> On 08/07/2016 03:53 PM, Chin Liang See wrote:
> > Ensuring the baudrate divisor value doesn't exceed the max value
> > in the calculation.It will be capped at max value to ensure the
> > correct value being written into the register.
> > 
> > Signed-off-by: Chin Liang See <clsee at altera.com>
> > Cc: Marek Vasut <marex at denx.de>
> > Cc: Jagan Teki <jteki at openedev.com>
> > Cc: Dinh Nguyen <dinguyen at altera.com>
> > ---
> >  drivers/spi/cadence_qspi_apb.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/spi/cadence_qspi_apb.c
> > b/drivers/spi/cadence_qspi_apb.c
> > index 1a35d55..e6a8ecb 100644
> > --- a/drivers/spi/cadence_qspi_apb.c
> > +++ b/drivers/spi/cadence_qspi_apb.c
> > @@ -293,6 +293,10 @@ void cadence_qspi_apb_config_baudrate_div(void
> > *reg_base,
> >  	debug("%s: ref_clk %dHz sclk %dHz Div 0x%x\n", __func__,
> >  	      ref_clk_hz, sclk_hz, div);
> >  
> > +	/* ensure the baud rate doesn't exceed the max value */
> > +	if (div > CQSPI_REG_CONFIG_BAUD_MASK)
> > +		div = CQSPI_REG_CONFIG_BAUD_MASK;
> > +
> >  	div = (div & CQSPI_REG_CONFIG_BAUD_MASK) <<
> > CQSPI_REG_CONFIG_BAUD_LSB;
> 
> The capping happens here ^ already , doesn't it ?

I have initial thought too until someone file me a bug on this. The bug
happen when the calculated div = 16. After and with the mask, the value
writen to register is actually 0 (register field for baudrate divisor).

Thanks
Chin Liang



> 
> >  	reg |= div;
> >  	writel(reg, reg_base + CQSPI_REG_CONFIG);
> > 
> 
>