Re: [PATCH] spi/omap2_mcspi: Verify TX reg is empty after TX only xfer with DMA

[Grant Likely <grant.likely@secretlab.ca>]

On Wed, Oct 20, 2010 at 09:23:57AM -0700, Tony Lindgren wrote:
> * Ilkka Koskinen <ilkka.koskinen@nokia.com> [101019 06:55]:
> > In case of TX only with DMA, the driver assumes that the data
> > has been transferred once DMA callback in invoked. However,
> > SPI's shift register may still contain data. Thus, the driver
> > is supposed to verify that the register is empty and the end of
> > the SPI transfer has been reached.
> > 
> > Signed-off-by: Ilkka Koskinen <ilkka.koskinen@nokia.com>
> > Tested-by: Tuomas Katila <ext-tuomas.2.katila@nokia.com>
> 
> Grant, can you please queue this one?
> 
> Acked-by: Tony Lindgren <tony@atomide.com>

Applied, thanks.

g.

> 
> 
> > ---
> >  drivers/spi/omap2_mcspi.c |   39 ++++++++++++++++++++++++++-------------
> >  1 files changed, 26 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
> > index b3a94ca..a2e053c 100644
> > --- a/drivers/spi/omap2_mcspi.c
> > +++ b/drivers/spi/omap2_mcspi.c
> > @@ -296,6 +296,19 @@ static int omap2_mcspi_enable_clocks(struct omap2_mcspi *mcspi)
> >  	return 0;
> >  }
> >  
> > +static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
> > +{
> > +	unsigned long timeout;
> > +
> > +	timeout = jiffies + msecs_to_jiffies(1000);
> > +	while (!(__raw_readl(reg) & bit)) {
> > +		if (time_after(jiffies, timeout))
> > +			return -1;
> > +		cpu_relax();
> > +	}
> > +	return 0;
> > +}
> > +
> >  static unsigned
> >  omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> >  {
> > @@ -309,11 +322,14 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> >  	u32			l;
> >  	u8			* rx;
> >  	const u8		* tx;
> > +	void __iomem		*chstat_reg;
> >  
> >  	mcspi = spi_master_get_devdata(spi->master);
> >  	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
> >  	l = mcspi_cached_chconf0(spi);
> >  
> > +	chstat_reg = cs->base + OMAP2_MCSPI_CHSTAT0;
> > +
> >  	count = xfer->len;
> >  	c = count;
> >  	word_len = cs->word_len;
> > @@ -382,6 +398,16 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> >  	if (tx != NULL) {
> >  		wait_for_completion(&mcspi_dma->dma_tx_completion);
> >  		dma_unmap_single(NULL, xfer->tx_dma, count, DMA_TO_DEVICE);
> > +
> > +		/* for TX_ONLY mode, be sure all words have shifted out */
> > +		if (rx == NULL) {
> > +			if (mcspi_wait_for_reg_bit(chstat_reg,
> > +						OMAP2_MCSPI_CHSTAT_TXS) < 0)
> > +				dev_err(&spi->dev, "TXS timed out\n");
> > +			else if (mcspi_wait_for_reg_bit(chstat_reg,
> > +						OMAP2_MCSPI_CHSTAT_EOT) < 0)
> > +				dev_err(&spi->dev, "EOT timed out\n");
> > +		}
> >  	}
> >  
> >  	if (rx != NULL) {
> > @@ -435,19 +461,6 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> >  	return count;
> >  }
> >  
> > -static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
> > -{
> > -	unsigned long timeout;
> > -
> > -	timeout = jiffies + msecs_to_jiffies(1000);
> > -	while (!(__raw_readl(reg) & bit)) {
> > -		if (time_after(jiffies, timeout))
> > -			return -1;
> > -		cpu_relax();
> > -	}
> > -	return 0;
> > -}
> > -
> >  static unsigned
> >  omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
> >  {
> > -- 
> > 1.6.0.4
> >