[U-Boot] [PATCH 2/2] drivers/spi: fsl_qspi: improve timeout calculation

[Thomas Schaefer]

> Von: Jagan Teki <jagan at amarulasolutions.com> 
> Gesendet: Dienstag, 2. Juli 2019 13:12
> 
> On Mon, Jul 1, 2019 at 9:07 PM Thomas Schaefer <thomas.schaefer at kontron.com> wrote:
> >
> > Use readl_poll_timeout instead of explicit calculation
> >
> > Signed-off-by: Thomas Schaefer <thomas.schaefer at kontron.com>
> > ---
> >  drivers/spi/fsl_qspi.c | 17 ++++++-----------
> >  1 file changed, 6 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/spi/fsl_qspi.c b/drivers/spi/fsl_qspi.c index 
> > 2c5937509f..41abe1996f 100644
> > --- a/drivers/spi/fsl_qspi.c
> > +++ b/drivers/spi/fsl_qspi.c
> > @@ -10,6 +10,7 @@
> >  #include <spi.h>
> >  #include <asm/io.h>
> >  #include <linux/sizes.h>
> > +#include <linux/iopoll.h>
> >  #include <dm.h>
> >  #include <errno.h>
> >  #include <watchdog.h>
> > @@ -150,19 +151,13 @@ static void qspi_write32(u32 flags, u32 *addr, 
> > u32 val)  static inline int is_controller_busy(const struct 
> > fsl_qspi_priv *priv)  {
> >         u32 val;
> > -       const u32 mask = QSPI_SR_BUSY_MASK | QSPI_SR_AHB_ACC_MASK |
> > -                        QSPI_SR_IP_ACC_MASK;
> > -       unsigned long timeout = timer_get_us() + 1000;
> > +       u32 mask = QSPI_SR_BUSY_MASK | QSPI_SR_AHB_ACC_MASK |
> > +                  QSPI_SR_IP_ACC_MASK;
> >
> > -       do {
> > -               val = qspi_read32(priv->flags, &priv->regs->sr);
> > +       if (priv->flags & QSPI_FLAG_REGMAP_ENDIAN_BIG)
> > +               mask = (u32)cpu_to_be32(mask);
> 
> This look like a BE check, which was not there before isn't it?
> 

Hi Jagan,

The previous implementation was using the qspi_read32 function, that
implemented this endianess checking. As the readl_poll_timeout macro finally
ends with

#define __arch_getl(a)  (*(volatile unsigned int *)(a))

in arch/arm/include/asm/io.h. When swapping the 'mask' in case of BE, the
result is the same as when using qspi_read32 before.

However, I did not test this as the QSPI_FLAG_REGMAP_ENDIAN_BIG is not set
on i.MX7 systems.

Also I found that current linux kernel does this BE check (negated LE check)
with the 'mask' variable in drivers/spi/spi-fsl-qspi.c

if (!q->devtype_data->little_endian)
    mask = (u32)cpu_to_be32(mask);

Best reards,
Thomas