[U-Boot] [PATCH 1/1] arm: sunxi: Add NULL pointer check

[Maxime Ripard]

On Thu, Dec 13, 2018 at 09:12:57AM +0200, Stefan Mavrodiev wrote:
> 
> On 12/6/18 8:41 AM, Stefan Mavrodiev wrote:
> > 
> > On 12/5/18 5:46 PM, Maxime Ripard wrote:
> > > On Wed, Dec 05, 2018 at 02:27:57PM +0200, Stefan Mavrodiev wrote:
> > > > Current driver doesn't check if the destination pointer is NULL.
> > > > This cause the data from the FIFO to be stored inside the internal
> > > > SDRAM ( address 0 ).
> > > > 
> > > > The patch add simple check if the destination pointer is NULL.
> > > > 
> > > > Signed-off-by: Stefan Mavrodiev <stefan at olimex.com>
> > > > ---
> > > >   drivers/spi/sun4i_spi.c | 3 ++-
> > > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/spi/sun4i_spi.c b/drivers/spi/sun4i_spi.c
> > > > index b86b5a00ad..38cc743c61 100644
> > > > --- a/drivers/spi/sun4i_spi.c
> > > > +++ b/drivers/spi/sun4i_spi.c
> > > > @@ -129,7 +129,8 @@ static inline void
> > > > sun4i_spi_drain_fifo(struct sun4i_spi_priv *priv, int len)
> > > >         while (len--) {
> > > >           byte = readb(&priv->regs->rxdata);
> > > > -        *priv->rx_buf++ = byte;
> > > > +        if (priv->rx_buf)
> > > > +            *priv->rx_buf++ = byte;
> > > It seems pretty inefficient to test the pointer at each access, it
> > > would be better to check it once before starting the transfer.
> > > 
> > > I'm not sure if that can even happen?
> > 
> > I've tried to check that before draining the receive fifo, but
> > then the controller doesn't work. I'm thinking that the fifo must
> > be drained in any case.
>
> Any further comments?

I was expecting you to comment on whether the FIFO needed to be
drained or not :)

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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