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

[Simon Horman <horms@verge.net.au>]

On Fri, Jun 16, 2017 at 08:25:12AM +0200, Geert Uytterhoeven wrote:
> Hi Simon,
> 
> On Fri, Jun 16, 2017 at 8:06 AM, Simon Horman <horms@verge.net.au> 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@verge.net.au> wrote:
> >> > Add complete to DMA ops to allow DMAC implementation dependent
> >> > handling of DMA completion.
> >> >
> >> > Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
> >> > ---
> >> >  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?

Thanks, I see that is still a problem.

As there is only one other driver and its closerly related
perhaps it could just implement the callback in this patch?

> >> > +}
> >> > +
> >> >  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@linux-m68k.org
> 
> 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
>