[U-Boot] [Patch] fsl_esdhc: Fix DMA transfer completion waiting loop

Gabbasov, Andrew
2013-06-10T14:51:16Z

Hi Dirk,
________________________________________
> From: Behme, Dirk - Bosch
> Sent: Monday, June 10, 2013 16:06
> To: Gabbasov, Andrew
> Cc: u-boot at lists.denx.de; Stefano Babic; Fleming Andy-AFLEMING
> Subject: Re: [U-Boot] [Patch] fsl_esdhc: Fix DMA transfer completion waiting loop
>
> On 08.04.2013 11:06, Andrew Gabbasov wrote:
> > Rework the waiting for transfer completion loop condition
> > to continue waiting until both Transfer Complete and DMA End
> > interrupts occur. Checking of DLA bit in Present State register
> > looks not needed in addition to interrupts status checking,
> > so it can be removed from the condition. Also, DMA Error
> > condition is added to the list of data errors, checked in the loop.
> >
> > Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
> > ---
> > drivers/mmc/fsl_esdhc.c | 3 +--
> > include/fsl_esdhc.h | 4 +++-
> > 2 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> > index 54b5363..814bba4 100644
> > --- a/drivers/mmc/fsl_esdhc.c
> > +++ b/drivers/mmc/fsl_esdhc.c
> > @@ -400,8 +400,7 @@ esdhc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
> >
> > if (irqstat & DATA_ERR)
> > return COMM_ERR;
> > - } while (!(irqstat & IRQSTAT_TC) &&
> > - (esdhc_read32(&regs->prsstat) & PRSSTAT_DLA));
> > + } while ((irqstat & DATA_COMPLETE) != DATA_COMPLETE);
> > #endif
> > }
> >
> > diff --git a/include/fsl_esdhc.h b/include/fsl_esdhc.h
> > index 47d2fe4..ea0880b 100644
> > --- a/include/fsl_esdhc.h
> > +++ b/include/fsl_esdhc.h
> > @@ -63,7 +63,9 @@
> > #define IRQSTAT_CC (0x00000001)
> >
> > #define CMD_ERR (IRQSTAT_CIE | IRQSTAT_CEBE | IRQSTAT_CCE)
> > -#define DATA_ERR (IRQSTAT_DEBE | IRQSTAT_DCE | IRQSTAT_DTOE)
> > +#define DATA_ERR (IRQSTAT_DEBE | IRQSTAT_DCE | IRQSTAT_DTOE | \
> > + IRQSTAT_DMAE)
> > +#define DATA_COMPLETE (IRQSTAT_TC | IRQSTAT_DINT)
> >
> > #define IRQSTATEN 0x0002e034
> > #define IRQSTATEN_DMAE (0x10000000)
>
> I haven't tested this myself, but I got the following issue report
> regarding this patch:
>
> Using a SANDISK ULTRA II 8GB card (or alternatively Transcend 16GB or
> 32GB cards) and trying an mmc write [1] into the upper area of the 8GB
> card makes the write hang in 9 of 10 cases. Sometimes even more.
> Reverting this patch make these writes work again.
>
> mmc read does work fine, though. Even newer SANDISK Extreme III or
> several micro SD cards are working fine.
>
> Any idea?
>
> Best regards
>
> Dirk

So far the only idea that comes into my mind is that DMA for some reason completes
its part of work too early so that the corresponding interrupt status bit appears and
has already been cleared even before entering this loop.

I will be trying to reproduce the issue.

Meanwhile, is it possible to ask the reporter (who obviously can reproduce it)
to try to add the debug print from the diff below and show what it prints when
the write command hangs and when it succeeds?

Thanks.

Best regards,
Andrew

diff -u fsl_esdhc.c.orig fsl_esdhc.c
--- fsl_esdhc.c.orig 2013-05-30 03:48:26.000000000 -0500
+++ fsl_esdhc.c 2013-06-10 09:38:30.071905119 -0500
@@ -329,6 +329,7 @@

irqstat = esdhc_read32(&regs->irqstat);
esdhc_write32(&regs->irqstat, irqstat);
+ printf("fsl_esdhc: irqstat = 0x%08x\n", irqstat);

/* Reset CMD and DATA portions on error */
if (irqstat & (CMD_ERR | IRQSTAT_CTOE)) {