[PATCH] mtd: cqspi: Wait for transfer completion

[Pratyush Yadav]

On 14/09/21 08:22PM, Marek Vasut wrote:
> On 9/14/21 7:42 PM, Pratyush Yadav wrote:
> > On 14/09/21 05:22AM, Marek Vasut wrote:
> > > Wait for the read/write transfer finish bit get actually cleared,
> > > this does not happen immediately on at least SoCFPGA Gen5.
> > > 
> > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > Cc: Jagan Teki <jagan at amarulasolutions.com>
> > > Cc: Vignesh R <vigneshr at ti.com>
> > > Cc: Pratyush Yadav <p.yadav at ti.com>
> > > ---
> > >   drivers/spi/cadence_qspi_apb.c | 17 +++++++++++++++++
> > >   1 file changed, 17 insertions(+)
> > > 
> > > diff --git a/drivers/spi/cadence_qspi_apb.c b/drivers/spi/cadence_qspi_apb.c
> > > index 429ee335db6..2cdf4c9c9f8 100644
> > > --- a/drivers/spi/cadence_qspi_apb.c
> > > +++ b/drivers/spi/cadence_qspi_apb.c
> > > @@ -858,6 +858,14 @@ cadence_qspi_apb_indirect_read_execute(struct cadence_spi_plat *plat,
> > >   	writel(CQSPI_REG_INDIRECTRD_DONE,
> > >   	       plat->regbase + CQSPI_REG_INDIRECTRD);
> > > +	/* Check indirect done status */
> > > +	ret = wait_for_bit_le32(plat->regbase + CQSPI_REG_INDIRECTRD,
> > > +				CQSPI_REG_INDIRECTRD_DONE, 0, 10, 0);
> > > +	if (ret) {
> > > +		printf("Indirect read clear completion error (%i)\n", ret);
> > > +		goto failrd;
> > > +	}
> > > +
> > 
> > Huh, this is strange. I would expect the bit to clear immediately since
> > it doesn't really do any operation on the flash. How long does it
> > usually take to clear? If you don't wait for it to clear does anything
> > break?
> 
> Often it does clear immediately, but there were a few odd cases where it did
> not happen right away, in which case I had transfer corruption.

By "transfer corruption" do you mean the current transfer gets corrupted 
or the next one?

We get here _after_ the transfer is completed and this bit should have 
little to do with the data received. If the current transfer fails then 
I suspect something else might be going wrong the this is just a symptom 
of the problem.

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.