Re: [PATCH/RFC 2/5] mmc: tmio: add complete to DMA ops

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Hi Simon,

On Fri, Jun 16, 2017 at 8:06 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
> On Fri, Jun 09, 2017 at 09:35:20AM +0200, Geert Uytterhoeven wrote:
>> On Thu, Jun 8, 2017 at 3:09 PM, Simon Horman <horms+renesas@xxxxxxxxxxxx> wrote:
>> > Add complete to DMA ops to allow DMAC implementation dependent
>> > handling of DMA completion.
>> >
>> > Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
>> > ---
>> >  drivers/mmc/host/tmio_mmc.h      |  1 +
>> >  drivers/mmc/host/tmio_mmc_core.c | 10 ++++++++--
>> >  2 files changed, 9 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
>> > index 9c94b6eb9b49..82725f9de359 100644
>> > --- a/drivers/mmc/host/tmio_mmc.h
>> > +++ b/drivers/mmc/host/tmio_mmc.h
>> > @@ -121,6 +121,7 @@ struct tmio_mmc_dma_ops {
>> >                         struct tmio_mmc_data *pdata);
>> >         void (*release)(struct tmio_mmc_host *host);
>> >         void (*abort)(struct tmio_mmc_host *host);
>> > +       void (*complete)(struct tmio_mmc_host *host);
>> >  };
>> >
>> >  struct tmio_mmc_host {
>> > diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
>> > index 0e76e099dc7f..26fe9bb64849 100644
>> > --- a/drivers/mmc/host/tmio_mmc_core.c
>> > +++ b/drivers/mmc/host/tmio_mmc_core.c
>> > @@ -86,6 +86,12 @@ static inline void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
>> >                 host->dma_ops->abort(host);
>> >  }
>> >
>> > +static inline void tmio_mmc_complete_dma(struct tmio_mmc_host *host)
>> > +{
>> > +       if (host->dma_ops)
>> > +               host->dma_ops->complete(host);
>>
>> I believe this will cause a crash and thus break bisection, as no driver
>> fills in the complete pointer yet.
>
> Indeed. And it seems to cause a panic on non-Gen3 users of the driver.
>
> I think the fix should be:
>
> diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
> index 26fe9bb64849..9ec2e933b6f0 100644
> --- a/drivers/mmc/host/tmio_mmc_core.c
> +++ b/drivers/mmc/host/tmio_mmc_core.c
> @@ -88,7 +88,7 @@ static inline void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
>
>  static inline void tmio_mmc_complete_dma(struct tmio_mmc_host *host)
>  {
> -       if (host->dma_ops)
> +       if (host->dma_ops && host->dma_ops->complete)
>                 host->dma_ops->complete(host);
>  }

Is it? Now nothing will be completed?

The old code did:

     complete(&host->dma_dataend);

so perhaps

    else
            complete(&host->dma_dataend);

with the "else" branch to be deleted when all drivers that need it provide
their own complete callback?

>> > +}
>> > +
>> >  void tmio_mmc_enable_mmc_irqs(struct tmio_mmc_host *host, u32 i)
>> >  {
>> >         host->sdcard_irq_mask &= ~(i & TMIO_MASK_IRQ);
>> > @@ -604,11 +610,11 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host, unsigned int stat)
>> >
>> >                 if (done) {
>> >                         tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_DATAEND);
>> > -                       complete(&host->dma_dataend);
>> > +                       tmio_mmc_complete_dma(host);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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